SimpleEvaluationContext with dedicated factory methods for common cases
Aligned with DataBindingPropertyAccessor and shown in ref doc examples. Issue: SPR-16588
This commit is contained in:
Juergen Hoeller
parent
025ee83403
commit
51c57d77d9
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@ -1,5 +1,5 @@
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/*
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* Copyright 2002-2017 the original author or authors.
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* Copyright 2002-2018 the original author or authors.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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@ -57,13 +57,13 @@ public enum SpelMessage {
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"Property or field ''{0}'' cannot be found on null"),
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PROPERTY_OR_FIELD_NOT_READABLE(Kind.ERROR, 1008,
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"Property or field ''{0}'' cannot be found on object of type ''{1}'' - maybe not public?"),
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"Property or field ''{0}'' cannot be found on object of type ''{1}'' - maybe not public or not valid?"),
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PROPERTY_OR_FIELD_NOT_WRITABLE_ON_NULL(Kind.ERROR, 1009,
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"Property or field ''{0}'' cannot be set on null"),
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PROPERTY_OR_FIELD_NOT_WRITABLE(Kind.ERROR, 1010,
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"Property or field ''{0}'' cannot be set on object of type ''{1}'' - maybe not public?"),
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"Property or field ''{0}'' cannot be set on object of type ''{1}'' - maybe not public or not writable?"),
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METHOD_CALL_ON_NULL_OBJECT_NOT_ALLOWED(Kind.ERROR, 1011,
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"Method call: Attempted to call method {0} on null context object"),
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@ -22,12 +22,12 @@ import java.lang.reflect.Method;
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* A {@link org.springframework.expression.PropertyAccessor} variant for data binding
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* purposes, using reflection to access properties for reading and possibly writing.
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*
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* <p>A property can be accessed through a public getter method (when being read)
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* <p>A property can be referenced through a public getter method (when being read)
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* or a public setter method (when being written), and also as a public field.
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*
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* <p>This accessor is explicitly designed for user-level property evaluation
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* and does not resolve technical properties on {@code java.lang.Object}.
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* For more resolution power, choose {@link ReflectivePropertyAccessor} instead.
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* <p>This accessor is explicitly designed for user-declared properties and does not
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* resolve technical properties on {@code java.lang.Object} or {@code java.lang.Class}.
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* For unrestricted resolution, choose {@link ReflectivePropertyAccessor} instead.
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*
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* @author Juergen Hoeller
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* @since 4.3.15
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@ -49,20 +49,21 @@ public class DataBindingPropertyAccessor extends ReflectivePropertyAccessor {
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}
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@Override
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protected boolean isCandidateForProperty(Method method) {
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return (method.getDeclaringClass() != Object.class);
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protected boolean isCandidateForProperty(Method method, Class<?> targetClass) {
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Class<?> clazz = method.getDeclaringClass();
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return (clazz != Object.class && clazz != Class.class && !ClassLoader.class.isAssignableFrom(targetClass));
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}
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/**
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* Create a new data-binding property accessor for read-only access.
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* Create a new data-binding property accessor for read-only operations.
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*/
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public static DataBindingPropertyAccessor forReadOnlyAccess() {
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return new DataBindingPropertyAccessor(false);
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}
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/**
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* Create a new data-binding property accessor for read-write access.
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* Create a new data-binding property accessor for read-write operations.
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*/
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public static DataBindingPropertyAccessor forReadWriteAccess() {
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return new DataBindingPropertyAccessor(true);
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@ -48,7 +48,7 @@ import org.springframework.util.StringUtils;
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* A powerful {@link PropertyAccessor} that uses reflection to access properties
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* for reading and possibly also for writing.
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*
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* <p>A property can be accessed through a public getter method (when being read)
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* <p>A property can be referenced through a public getter method (when being read)
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* or a public setter method (when being written), and also as a public field.
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*
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* @author Andy Clement
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@ -409,7 +409,7 @@ public class ReflectivePropertyAccessor implements PropertyAccessor {
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Method[] methods = getSortedClassMethods(clazz);
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for (String methodSuffix : methodSuffixes) {
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for (Method method : methods) {
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if (isCandidateForProperty(method) && method.getName().equals(prefix + methodSuffix) &&
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if (isCandidateForProperty(method, clazz) && method.getName().equals(prefix + methodSuffix) &&
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method.getParameterCount() == numberOfParams &&
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(!mustBeStatic || Modifier.isStatic(method.getModifiers())) &&
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(requiredReturnTypes.isEmpty() || requiredReturnTypes.contains(method.getReturnType()))) {
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@ -425,9 +425,10 @@ public class ReflectivePropertyAccessor implements PropertyAccessor {
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* <p>The default implementation considers any method as a candidate, even for
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* non-user-declared properties on the {@link Object} base class.
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* @param method the Method to evaluate
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* @param targetClass the concrete target class that is being introspected
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* @since 4.3.15
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*/
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protected boolean isCandidateForProperty(Method method) {
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protected boolean isCandidateForProperty(Method method, Class<?> targetClass) {
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return true;
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}
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@ -518,25 +519,25 @@ public class ReflectivePropertyAccessor implements PropertyAccessor {
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if (target == null) {
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return this;
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}
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Class<?> type = (target instanceof Class ? (Class<?>) target : target.getClass());
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if (type.isArray()) {
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Class<?> clazz = (target instanceof Class ? (Class<?>) target : target.getClass());
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if (clazz.isArray()) {
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return this;
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}
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PropertyCacheKey cacheKey = new PropertyCacheKey(type, name, target instanceof Class);
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PropertyCacheKey cacheKey = new PropertyCacheKey(clazz, name, target instanceof Class);
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InvokerPair invocationTarget = this.readerCache.get(cacheKey);
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if (invocationTarget == null || invocationTarget.member instanceof Method) {
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Method method = (Method) (invocationTarget != null ? invocationTarget.member : null);
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if (method == null) {
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method = findGetterForProperty(name, type, target);
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method = findGetterForProperty(name, clazz, target);
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if (method != null) {
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invocationTarget = new InvokerPair(method, new TypeDescriptor(new MethodParameter(method, -1)));
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ReflectionUtils.makeAccessible(method);
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this.readerCache.put(cacheKey, invocationTarget);
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}
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}
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if (method != null && isCandidateForProperty(method)) {
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if (method != null) {
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return new OptimalPropertyAccessor(invocationTarget);
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}
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}
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@ -544,7 +545,7 @@ public class ReflectivePropertyAccessor implements PropertyAccessor {
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if (invocationTarget == null || invocationTarget.member instanceof Field) {
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Field field = (invocationTarget != null ? (Field) invocationTarget.member : null);
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if (field == null) {
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field = findField(name, type, target instanceof Class);
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field = findField(name, clazz, target instanceof Class);
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if (field != null) {
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invocationTarget = new InvokerPair(field, new TypeDescriptor(field));
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ReflectionUtils.makeAccessible(field);
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@ -16,13 +16,13 @@
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package org.springframework.expression.spel.support;
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import java.util.ArrayList;
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import java.util.Arrays;
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import java.util.Collections;
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import java.util.HashMap;
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import java.util.List;
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import java.util.Map;
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import org.springframework.core.convert.ConversionService;
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import org.springframework.expression.BeanResolver;
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import org.springframework.expression.ConstructorResolver;
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import org.springframework.expression.EvaluationContext;
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@ -41,34 +41,42 @@ import org.springframework.lang.Nullable;
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* A basic implementation of {@link EvaluationContext} that focuses on a subset
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* of essential SpEL features and configuration options.
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*
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* <p>In many cases, the full extent of the SpEL language is not
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* required and should be meaningfully restricted. Examples include but are not
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* limited to data binding expressions, property-based filters, and others. To
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* that effect, {@code SimpleEvaluationContext} is tailored to support only a
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* subset of the SpEL language syntax, e.g. excluding references to Java types,
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* constructors, and bean references.
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* <p>In many cases, the full extent of the SpEL language is not required and
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* should be meaningfully restricted. Examples include but are not limited to
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* data binding expressions, property-based filters, and others. To that effect,
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* {@code SimpleEvaluationContext} is tailored to support only a subset of the
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* SpEL language syntax, e.g. excluding references to Java types, constructors,
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* and bean references.
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*
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* <p>When creating {@code SimpleEvaluationContext} you need to choose the level
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* of support you need to deal with properties and methods in SpEL expressions.
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* By default, {@link SimpleEvaluationContext#create()} enables only read access
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* to properties via {@link DataBindingPropertyAccessor}. Alternatively, use
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* {@link SimpleEvaluationContext#builder()} to configure the exact level of
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* support needed, targeting one of, or some combination of the following:
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* of support you need to deal with properties and methods in SpEL expressions:
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* <ul>
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* <li>Custom {@code PropertyAccessor} only (no reflection).</li>
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* <li>Data binding properties for read-only access.</li>
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* <li>Data binding properties for read and write.</li>
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* <li>Custom {@code PropertyAccessor} only (no reflection)</li>
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* <li>Data binding properties for read-only access</li>
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* <li>Data binding properties for read and write</li>
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* </ul>
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*
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* <p>Note that {@code SimpleEvaluationContext} cannot be configured with a
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* default root object. Instead it is meant to be created once and used
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* repeatedly through method variants on
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* {@link org.springframework.expression.Expression Expression} that accept
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* both an {@code EvaluationContext} and a root object.
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* <p>Conveniently, {@link SimpleEvaluationContext#forReadOnlyDataBinding()}
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* enables read access to properties via {@link DataBindingPropertyAccessor};
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* same for {@link SimpleEvaluationContext#forReadWriteDataBinding()} when
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* write access is needed as well. Alternatively, configure custom accessors
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* via {@link SimpleEvaluationContext#forPropertyAccessors}.
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*
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* <p>Note that {@code SimpleEvaluationContext} cannot be configured with
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* a default root object. Instead it is meant to be created once and used
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* repeatedly through {@code getValue} calls on a pre-compiled
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* {@link org.springframework.expression.Expression} with both an
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* {@code EvaluationContext} and a root object as arguments
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*
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* <p>For more flexibility, consider {@link StandardEvaluationContext} instead.
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*
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* @author Rossen Stoyanchev
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* @author Juergen Hoeller
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* @since 4.3.15
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* @see #forReadOnlyDataBinding()
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* @see #forReadWriteDataBinding()
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* @see StandardEvaluationContext
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* @see StandardTypeConverter
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* @see DataBindingPropertyAccessor
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*/
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public class SimpleEvaluationContext implements EvaluationContext {
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@ -80,10 +88,6 @@ public class SimpleEvaluationContext implements EvaluationContext {
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private final List<PropertyAccessor> propertyAccessors;
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private final List<ConstructorResolver> constructorResolvers = Collections.emptyList();
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private final List<MethodResolver> methodResolvers = Collections.emptyList();
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private final TypeConverter typeConverter;
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private final TypeComparator typeComparator = new StandardTypeComparator();
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@ -94,8 +98,8 @@ public class SimpleEvaluationContext implements EvaluationContext {
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private SimpleEvaluationContext(List<PropertyAccessor> accessors, @Nullable TypeConverter converter) {
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this.propertyAccessors = Collections.unmodifiableList(new ArrayList<>(accessors));
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this.typeConverter = converter != null ? converter : new StandardTypeConverter();
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this.propertyAccessors = accessors;
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this.typeConverter = (converter != null ? converter : new StandardTypeConverter());
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}
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@ -122,7 +126,7 @@ public class SimpleEvaluationContext implements EvaluationContext {
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*/
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@Override
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public List<ConstructorResolver> getConstructorResolvers() {
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return this.constructorResolvers;
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return Collections.emptyList();
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}
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/**
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@ -130,7 +134,7 @@ public class SimpleEvaluationContext implements EvaluationContext {
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*/
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@Override
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public List<MethodResolver> getMethodResolvers() {
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return this.methodResolvers;
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return Collections.emptyList();
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}
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/**
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@ -170,7 +174,6 @@ public class SimpleEvaluationContext implements EvaluationContext {
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return this.typeComparator;
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}
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/**
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* Return an instance of {@link StandardOperatorOverloader}.
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*/
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@ -192,26 +195,31 @@ public class SimpleEvaluationContext implements EvaluationContext {
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/**
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* Create a {@code SimpleEvaluationContext} with read-only access to
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* public properties via {@link DataBindingPropertyAccessor}.
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* <p>Effectively, a shortcut for:
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* <pre class="code">
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* SimpleEvaluationContext context = SimpleEvaluationContext.builder()
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* .dataBindingPropertyAccessor(true)
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* .build();
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* </pre>
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* @see #builder()
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* Create a {@code SimpleEvaluationContext} for the specified
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* {@link PropertyAccessor} delegates.
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* @see ReflectivePropertyAccessor
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* @see DataBindingPropertyAccessor
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*/
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public static SimpleEvaluationContext create() {
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return new Builder().dataBindingPropertyAccessor(true).build();
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public static Builder forPropertyAccessors(PropertyAccessor... accessors) {
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return new Builder(accessors);
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}
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/**
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* Return a builder to create a {@code SimpleEvaluationContext}.
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* @see #create()
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* Create a {@code SimpleEvaluationContext} for read-only access to
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* public properties via {@link DataBindingPropertyAccessor}.
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* @see DataBindingPropertyAccessor#forReadOnlyAccess()
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*/
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public static Builder builder() {
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return new Builder();
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public static Builder forReadOnlyDataBinding() {
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return new Builder(DataBindingPropertyAccessor.forReadOnlyAccess());
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}
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/**
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* Create a {@code SimpleEvaluationContext} for read-write access to
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* public properties via {@link DataBindingPropertyAccessor}.
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* @see DataBindingPropertyAccessor#forReadOnlyAccess()
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*/
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public static Builder forReadWriteDataBinding() {
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return new Builder(DataBindingPropertyAccessor.forReadWriteAccess());
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}
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@ -220,43 +228,41 @@ public class SimpleEvaluationContext implements EvaluationContext {
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*/
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public static class Builder {
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private final List<PropertyAccessor> propertyAccessors = new ArrayList<>();
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private final List<PropertyAccessor> propertyAccessors;
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@Nullable
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private TypeConverter typeConverter;
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/**
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* Enable access to public properties for data binding purposes.
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* <p>Effectively, a shortcut for
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* {@code propertyAccessor(new DataBindingPropertyAccessor(boolean))}.
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* @param readOnlyAccess whether to read-only access to properties,
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* {@code "true"}, or read and write, {@code "false"}.
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*/
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public Builder dataBindingPropertyAccessor(boolean readOnlyAccess) {
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return propertyAccessor(readOnlyAccess ?
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DataBindingPropertyAccessor.forReadOnlyAccess() :
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DataBindingPropertyAccessor.forReadWriteAccess());
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}
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/**
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* Register a custom accessor for properties in expressions.
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* <p>By default, the builder does not enable property access.
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*/
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public Builder propertyAccessor(PropertyAccessor... accessors) {
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this.propertyAccessors.addAll(Arrays.asList(accessors));
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return this;
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public Builder(PropertyAccessor... accessors) {
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this.propertyAccessors = Arrays.asList(accessors);
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}
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/**
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* Register a custom {@link TypeConverter}.
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* <p>By default {@link StandardTypeConverter} is used.
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* <p>By default a {@link StandardTypeConverter} backed by a
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* {@link org.springframework.core.convert.support.DefaultConversionService}
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* is used.
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* @see #withConversionService
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* @see StandardTypeConverter#StandardTypeConverter()
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*/
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public Builder typeConverter(TypeConverter converter) {
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public Builder withTypeConverter(TypeConverter converter) {
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this.typeConverter = converter;
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return this;
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}
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/**
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* Register a custom {@link ConversionService}.
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* <p>By default a {@link StandardTypeConverter} backed by a
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* {@link org.springframework.core.convert.support.DefaultConversionService}
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* is used.
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* @see #withTypeConverter
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* @see StandardTypeConverter#StandardTypeConverter(ConversionService)
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*/
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public Builder withConversionService(ConversionService conversionService) {
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this.typeConverter = new StandardTypeConverter(conversionService);
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return this;
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}
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public SimpleEvaluationContext build() {
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return new SimpleEvaluationContext(this.propertyAccessors, this.typeConverter);
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}
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@ -1,5 +1,5 @@
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/*
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* Copyright 2002-2017 the original author or authors.
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* Copyright 2002-2018 the original author or authors.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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@ -42,6 +42,7 @@ public class StandardTypeConverter implements TypeConverter {
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/**
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* Create a StandardTypeConverter for the default ConversionService.
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* @see DefaultConversionService#getSharedInstance()
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*/
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public StandardTypeConverter() {
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this.conversionService = DefaultConversionService.getSharedInstance();
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@ -87,7 +87,7 @@ public class PropertyAccessTests extends AbstractExpressionTests {
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}
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assertFalse(expr.isWritable(context));
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try {
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expr.setValue(context,"abc");
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expr.setValue(context, "abc");
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fail("Should have failed - default property resolver cannot resolve on null");
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}
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catch (Exception ex) {
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@ -95,13 +95,13 @@ public class PropertyAccessTests extends AbstractExpressionTests {
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}
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}
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private void checkException(Exception e, SpelMessage expectedMessage) {
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if (e instanceof SpelEvaluationException) {
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SpelMessage sm = ((SpelEvaluationException)e).getMessageCode();
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assertEquals("Expected exception type did not occur",expectedMessage,sm);
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private void checkException(Exception ex, SpelMessage expectedMessage) {
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if (ex instanceof SpelEvaluationException) {
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SpelMessage sm = ((SpelEvaluationException) ex).getMessageCode();
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assertEquals("Expected exception type did not occur", expectedMessage, sm);
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}
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else {
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fail("Should be a SpelException "+e);
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fail("Should be a SpelException " + ex);
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}
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}
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@ -210,7 +210,12 @@ public class PropertyAccessTests extends AbstractExpressionTests {
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assertEquals("p2", expr.getValue(context, target));
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parser.parseExpression("name='p3'").getValue(context, target);
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assertEquals("p3", target.getName());
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assertEquals("p3", expr.getValue(context, target));
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expr.setValue(context, target, "p4");
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assertEquals("p4", target.getName());
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assertEquals("p4", expr.getValue(context, target));
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}
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@Test(expected = SpelEvaluationException.class)
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|
|
|||
|
|
@ -64,10 +64,9 @@ public class DefaultSubscriptionRegistry extends AbstractSubscriptionRegistry {
|
|||
/** Default maximum number of entries for the destination cache: 1024 */
|
||||
public static final int DEFAULT_CACHE_LIMIT = 1024;
|
||||
|
||||
/** Static evaluation context to re-use */
|
||||
private static SimpleEvaluationContext evaluationContext = SimpleEvaluationContext.builder()
|
||||
.propertyAccessor(new SimpMessageHeaderPropertyAccessor()).build();
|
||||
|
||||
/** Static evaluation context to reuse */
|
||||
private static EvaluationContext messageEvalContext =
|
||||
SimpleEvaluationContext.forPropertyAccessors(new SimpMessageHeaderPropertyAccessor()).build();
|
||||
|
||||
|
||||
private PathMatcher pathMatcher = new AntPathMatcher();
|
||||
|
|
@ -213,7 +212,7 @@ public class DefaultSubscriptionRegistry extends AbstractSubscriptionRegistry {
|
|||
continue;
|
||||
}
|
||||
try {
|
||||
if (Boolean.TRUE.equals(expression.getValue(evaluationContext, message, Boolean.class))) {
|
||||
if (Boolean.TRUE.equals(expression.getValue(messageEvalContext, message, Boolean.class))) {
|
||||
result.add(sessionId, subId);
|
||||
}
|
||||
}
|
||||
|
|
|
|||
|
|
@ -186,9 +186,8 @@ out-of-the-box implementations.
|
|||
|
||||
* `SimpleEvaluationContext` -- exposes a subset of essential SpEL language features and
|
||||
configuration options, for categories of expressions that do not require the full extent
|
||||
of the SpEL language syntax and should be meaningfully restricted. Examples
|
||||
include but are not limited to data binding expressions, property-based filters, and
|
||||
others.
|
||||
of the SpEL language syntax and should be meaningfully restricted. Examples include but
|
||||
are not limited to data binding expressions, property-based filters, and others.
|
||||
|
||||
* `StandardEvaluationContext` -- exposes the full set of SpEL language features and
|
||||
configuration options. You may use it to specify a default root object, and to configure
|
||||
|
|
@ -201,9 +200,9 @@ By default, the `create()` static factory method enables only read access to pro
|
|||
You can also obtain a builder to configure the exact level of support needed, targeting
|
||||
one of, or some combination of the following:
|
||||
|
||||
. Custom {@code PropertyAccessor} only (no reflection).
|
||||
. Data binding properties for read-only access.
|
||||
. Data binding properties for read and write.
|
||||
. Custom {@code PropertyAccessor} only (no reflection)
|
||||
. Data binding properties for read-only access
|
||||
. Data binding properties for read and write
|
||||
|
||||
|
||||
[[expressions-type-conversion]]
|
||||
|
|
@ -232,11 +231,10 @@ being placed in it. A simple example:
|
|||
Simple simple = new Simple();
|
||||
simple.booleanList.add(true);
|
||||
|
||||
SimpleEvaluationContext context = SimpleEvaluationContext().create();
|
||||
EvaluationContext context = SimpleEvaluationContext().forReadOnlyDataBinding().build();
|
||||
|
||||
// false is passed in here as a string. SpEL and the conversion service will
|
||||
// correctly recognize that it needs to be a Boolean and convert it
|
||||
|
||||
parser.parseExpression("booleanList[0]").setValue(context, simple, "false");
|
||||
|
||||
// b will be false
|
||||
|
|
@ -609,7 +607,7 @@ arrays and lists are obtained using square bracket notation.
|
|||
[subs="verbatim,quotes"]
|
||||
----
|
||||
ExpressionParser parser = new SpelExpressionParser();
|
||||
SimpleEvaluationContext context = SimpleEvaluationContext.create();
|
||||
EvaluationContext context = SimpleEvaluationContext.forReadOnlyDataBinding().build();
|
||||
|
||||
// Inventions Array
|
||||
|
||||
|
|
@ -851,33 +849,33 @@ operators are demonstrated below.
|
|||
[subs="verbatim,quotes"]
|
||||
----
|
||||
// Addition
|
||||
int two = parser.parseExpression("1 + 1").getValue(Integer.class); // 2
|
||||
int two = parser.parseExpression("1 + 1").getValue(Integer.class); // 2
|
||||
|
||||
String testString = parser.parseExpression(
|
||||
"'test' + ' ' + 'string'").getValue(String.class); // 'test string'
|
||||
"'test' + ' ' + 'string'").getValue(String.class); // 'test string'
|
||||
|
||||
// Subtraction
|
||||
int four = parser.parseExpression("1 - -3").getValue(Integer.class); // 4
|
||||
int four = parser.parseExpression("1 - -3").getValue(Integer.class); // 4
|
||||
|
||||
double d = parser.parseExpression("1000.00 - 1e4").getValue(Double.class); // -9000
|
||||
double d = parser.parseExpression("1000.00 - 1e4").getValue(Double.class); // -9000
|
||||
|
||||
// Multiplication
|
||||
int six = parser.parseExpression("-2 * -3").getValue(Integer.class); // 6
|
||||
int six = parser.parseExpression("-2 * -3").getValue(Integer.class); // 6
|
||||
|
||||
double twentyFour = parser.parseExpression("2.0 * 3e0 * 4").getValue(Double.class); // 24.0
|
||||
double twentyFour = parser.parseExpression("2.0 * 3e0 * 4").getValue(Double.class); // 24.0
|
||||
|
||||
// Division
|
||||
int minusTwo = parser.parseExpression("6 / -3").getValue(Integer.class); // -2
|
||||
int minusTwo = parser.parseExpression("6 / -3").getValue(Integer.class); // -2
|
||||
|
||||
double one = parser.parseExpression("8.0 / 4e0 / 2").getValue(Double.class); // 1.0
|
||||
double one = parser.parseExpression("8.0 / 4e0 / 2").getValue(Double.class); // 1.0
|
||||
|
||||
// Modulus
|
||||
int three = parser.parseExpression("7 % 4").getValue(Integer.class); // 3
|
||||
int three = parser.parseExpression("7 % 4").getValue(Integer.class); // 3
|
||||
|
||||
int one = parser.parseExpression("8 / 5 % 2").getValue(Integer.class); // 1
|
||||
int one = parser.parseExpression("8 / 5 % 2").getValue(Integer.class); // 1
|
||||
|
||||
// Operator precedence
|
||||
int minusTwentyOne = parser.parseExpression("1+2-3*8").getValue(Integer.class); // -21
|
||||
int minusTwentyOne = parser.parseExpression("1+2-3*8").getValue(Integer.class); // -21
|
||||
----
|
||||
|
||||
|
||||
|
|
@ -892,14 +890,13 @@ done within a call to `setValue` but can also be done inside a call to `getValue
|
|||
[subs="verbatim,quotes"]
|
||||
----
|
||||
Inventor inventor = new Inventor();
|
||||
SimpleEvaluationContext context = SimpleEvaluationContext.create();
|
||||
EvaluationContext context = SimpleEvaluationContext.forReadWriteDataBinding().build();
|
||||
|
||||
parser.parseExpression("Name").setValue(context, inventor, "Alexander Seovic2");
|
||||
parser.parseExpression("Name").setValue(context, inventor, "Aleksandar Seovic");
|
||||
|
||||
// alternatively
|
||||
|
||||
String aleks = parser.parseExpression(
|
||||
"Name = 'Alexandar Seovic'").getValue(context, inventor, String.class);
|
||||
"Name = 'Aleksandar Seovic'").getValue(context, inventor, String.class);
|
||||
----
|
||||
|
||||
|
||||
|
|
@ -960,12 +957,12 @@ are set using the method setVariable on `EvaluationContext` implementations.
|
|||
[subs="verbatim,quotes"]
|
||||
----
|
||||
Inventor tesla = new Inventor("Nikola Tesla", "Serbian");
|
||||
SimpleEvaluationContext context = SimpleEvaluationContext.create();
|
||||
|
||||
EvaluationContext context = SimpleEvaluationContext.forReadWriteDataBinding().build();
|
||||
context.setVariable("newName", "Mike Tesla");
|
||||
|
||||
parser.parseExpression("Name = #newName").getValue(context, tesla);
|
||||
|
||||
System.out.println(tesla.getName()) // "Mike Tesla"
|
||||
System.out.println(tesla.getName()) // "Mike Tesla"
|
||||
----
|
||||
|
||||
|
||||
|
|
@ -986,8 +983,8 @@ an expression are evaluated, #root always refers to the root.
|
|||
|
||||
// create parser and set variable 'primes' as the array of integers
|
||||
ExpressionParser parser = new SpelExpressionParser();
|
||||
SimpleEvaluationContext context = SimpleEvaluationContext.create();
|
||||
context.setVariable("primes",primes);
|
||||
EvaluationContext context = SimpleEvaluationContext.forReadOnlyDataAccess();
|
||||
context.setVariable("primes", primes);
|
||||
|
||||
// all prime numbers > 10 from the list (using selection ?{...})
|
||||
// evaluates to [11, 13, 17]
|
||||
|
|
@ -1008,7 +1005,7 @@ expression string. The function is registered through the `EvaluationContext`.
|
|||
----
|
||||
Method method = ...;
|
||||
|
||||
SimpleEvaluationContext context = SimpleEvaluationContext.create();
|
||||
EvaluationContext context = SimpleEvaluationContext.forReadOnlyDataBinding().build();
|
||||
context.setVariable("myFunction", method);
|
||||
----
|
||||
|
||||
|
|
@ -1020,7 +1017,7 @@ For example, given a utility method to reverse a string is shown below:
|
|||
public abstract class StringUtils {
|
||||
|
||||
public static String reverseString(String input) {
|
||||
StringBuilder backwards = new StringBuilder();
|
||||
StringBuilder backwards = new StringBuilder(input.length());
|
||||
for (int i = 0; i < input.length(); i++)
|
||||
backwards.append(input.charAt(input.length() - 1 - i));
|
||||
}
|
||||
|
|
@ -1035,13 +1032,13 @@ The above method can then be registered and used as follows:
|
|||
[subs="verbatim,quotes"]
|
||||
----
|
||||
ExpressionParser parser = new SpelExpressionParser();
|
||||
SimpleEvaluationContext context = SimpleEvaluationContext.create();
|
||||
|
||||
EvaluationContext context = SimpleEvaluationContext.forReadOnlyDataBinding().build();
|
||||
context.setVariable("reverseString",
|
||||
StringUtils.class.getDeclaredMethod("reverseString", String.class));
|
||||
StringUtils.class.getDeclaredMethod("reverseString", String.class));
|
||||
|
||||
String helloWorldReversed = parser.parseExpression(
|
||||
"#reverseString('hello')").getValue(context, String.class);
|
||||
"#reverseString('hello')").getValue(context, String.class);
|
||||
----
|
||||
|
||||
|
||||
|
|
@ -1056,7 +1053,7 @@ lookup beans from an expression using the (@) symbol.
|
|||
[subs="verbatim,quotes"]
|
||||
----
|
||||
ExpressionParser parser = new SpelExpressionParser();
|
||||
StandardEvaluationContext context = StandardEvaluationContext.create();
|
||||
StandardEvaluationContext context = new StandardEvaluationContext();
|
||||
context.setBeanResolver(new MyBeanResolver());
|
||||
|
||||
// This will end up calling resolve(context,"foo") on MyBeanResolver during evaluation
|
||||
|
|
@ -1069,7 +1066,7 @@ To access a factory bean itself, the bean name should instead be prefixed with a
|
|||
[subs="verbatim,quotes"]
|
||||
----
|
||||
ExpressionParser parser = new SpelExpressionParser();
|
||||
StandardEvaluationContext context = StandardEvaluationContext.create();
|
||||
StandardEvaluationContext context = new StandardEvaluationContext();
|
||||
context.setBeanResolver(new MyBeanResolver());
|
||||
|
||||
// This will end up calling resolve(context,"&foo") on MyBeanResolver during evaluation
|
||||
|
|
@ -1124,7 +1121,7 @@ example:
|
|||
[subs="verbatim,quotes"]
|
||||
----
|
||||
String name = "Elvis Presley";
|
||||
String displayName = name != null ? name : "Unknown";
|
||||
String displayName = (name != null ? name : "Unknown");
|
||||
----
|
||||
|
||||
Instead you can use the Elvis operator, named for the resemblance to Elvis' hair style.
|
||||
|
|
@ -1135,8 +1132,7 @@ Instead you can use the Elvis operator, named for the resemblance to Elvis' hair
|
|||
ExpressionParser parser = new SpelExpressionParser();
|
||||
|
||||
String name = parser.parseExpression("name?:'Unknown'").getValue(String.class);
|
||||
|
||||
System.out.println(name); // 'Unknown'
|
||||
System.out.println(name); // 'Unknown'
|
||||
----
|
||||
|
||||
Here is a more complex example.
|
||||
|
|
@ -1145,19 +1141,15 @@ Here is a more complex example.
|
|||
[subs="verbatim,quotes"]
|
||||
----
|
||||
ExpressionParser parser = new SpelExpressionParser();
|
||||
EvaluationContext context = SimpleEvaluationContext.forReadOnlyDataBinding().build();
|
||||
|
||||
Inventor tesla = new Inventor("Nikola Tesla", "Serbian");
|
||||
SimpleEvaluationContext context = SimpleEvaluationContext.create();
|
||||
|
||||
String name = parser.parseExpression("Name?:'Elvis Presley'").getValue(context, tesla, String.class);
|
||||
|
||||
System.out.println(name); // Nikola Tesla
|
||||
System.out.println(name); // Nikola Tesla
|
||||
|
||||
tesla.setName(null);
|
||||
|
||||
name = parser.parseExpression("Name?:'Elvis Presley'").getValue(context, tesla, String.class);
|
||||
|
||||
System.out.println(name); // Elvis Presley
|
||||
System.out.println(name); // Elvis Presley
|
||||
----
|
||||
|
||||
|
||||
|
|
@ -1175,20 +1167,17 @@ safe navigation operator will simply return null instead of throwing an exceptio
|
|||
[subs="verbatim,quotes"]
|
||||
----
|
||||
ExpressionParser parser = new SpelExpressionParser();
|
||||
EvaluationContext context = SimpleEvaluationContext.forReadOnlyDataBinding().build();
|
||||
|
||||
Inventor tesla = new Inventor("Nikola Tesla", "Serbian");
|
||||
tesla.setPlaceOfBirth(new PlaceOfBirth("Smiljan"));
|
||||
|
||||
SimpleEvaluationContext context = SimpleEvaluationContext.create();
|
||||
|
||||
String city = parser.parseExpression("PlaceOfBirth?.City").getValue(context, tesla, String.class);
|
||||
System.out.println(city); // Smiljan
|
||||
System.out.println(city); // Smiljan
|
||||
|
||||
tesla.setPlaceOfBirth(null);
|
||||
|
||||
city = parser.parseExpression("PlaceOfBirth?.City").getValue(context, tesla, String.class);
|
||||
|
||||
System.out.println(city); // null - does not throw NullPointerException!!!
|
||||
System.out.println(city); // null - does not throw NullPointerException!!!
|
||||
----
|
||||
|
||||
[NOTE]
|
||||
|
|
|
|||
Loading…
Reference in New Issue