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Explicit notes on access to standard context beans in SpEL expressions 

Closes gh-25037
This commit is contained in:
Juergen Hoeller 2020-05-18 14:19:05 +02:00
parent 9d429e30de
commit 28177ad91b
2 changed files with 15 additions and 7 deletions
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7
spring-context/src/main/java/org/springframework/context/expression/StandardBeanExpressionResolver.java
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@ -1,5 +1,5 @@
/* /*
* Copyright 2002-2018 the original author or authors. * Copyright 2002-2020 the original author or authors.
* *
* Licensed under the Apache License, Version 2.0 (the "License"); * Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License. * you may not use this file except in compliance with the License.
@ -41,8 +41,13 @@ import org.springframework.util.StringUtils;
* {@link org.springframework.beans.factory.config.BeanExpressionResolver} * {@link org.springframework.beans.factory.config.BeanExpressionResolver}
* interface, parsing and evaluating Spring EL using Spring's expression module. * interface, parsing and evaluating Spring EL using Spring's expression module.
* *
* <p>All beans in the containing {@code BeanFactory} are made available as
* predefined variables with their common bean name, including standard context
* beans such as "environment", "systemProperties" and "systemEnvironment".
*
* @author Juergen Hoeller * @author Juergen Hoeller
* @since 3.0 * @since 3.0
* @see BeanExpressionContext#getBeanFactory()
* @see org.springframework.expression.ExpressionParser * @see org.springframework.expression.ExpressionParser
* @see org.springframework.expression.spel.standard.SpelExpressionParser * @see org.springframework.expression.spel.standard.SpelExpressionParser
* @see org.springframework.expression.spel.support.StandardEvaluationContext * @see org.springframework.expression.spel.support.StandardEvaluationContext

15
src/docs/asciidoc/core/core-expressions.adoc
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@ -539,8 +539,12 @@ example shows:
</bean> </bean>
---- ----
The `systemProperties` variable is predefined, so you can use it in your expressions, as All beans in the application context are available as predefined variables with their
the following example shows: common bean name. This includes standard context beans such as `environment` (of type
`org.springframework.core.env.Environment`) as well as `systemProperties` and
`systemEnvironment` (of type `Map<String, Object>`) for access to the runtime environment.
The following example shows access to the `systemProperties` bean as a SpEL variable:
[source,xml,indent=0,subs="verbatim"] [source,xml,indent=0,subs="verbatim"]
---- ----
@ -551,8 +555,7 @@ the following example shows:
</bean> </bean>
---- ----
Note that you do not have to prefix the predefined variable with the `#` Note that you do not have to prefix the predefined variable with the `#` symbol here.
symbol in this context.
You can also refer to other bean properties by name, as the following example shows: You can also refer to other bean properties by name, as the following example shows:
@ -576,8 +579,8 @@ You can also refer to other bean properties by name, as the following example sh
[[expressions-beandef-annotation-based]] [[expressions-beandef-annotation-based]]
=== Annotation Configuration === Annotation Configuration
To specify a default value, you can place the `@Value` annotation on fields, methods, and method or constructor To specify a default value, you can place the `@Value` annotation on fields, methods,
parameters. and method or constructor parameters.
The following example sets the default value of a field variable: The following example sets the default value of a field variable: