Context namespace exposes null-value attribute for property-placeholder element

Issue: SPR-13461

spring-context/src/main/java/org/springframework/context/config/PropertyOverrideBeanDefinitionParser.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2012 the original author or authors.
+ * Copyright 2002-2015 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -37,8 +37,8 @@ class PropertyOverrideBeanDefinitionParser extends AbstractPropertyLoadingBeanDe
 
 	@Override
 	protected void doParse(Element element, BeanDefinitionBuilder builder) {
-
 		super.doParse(element, builder);
+
 		builder.addPropertyValue("ignoreInvalidKeys",
 				Boolean.valueOf(element.getAttribute("ignore-unresolvable")));
 

spring-context/src/main/java/org/springframework/context/config/PropertyPlaceholderBeanDefinitionParser.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2011 the original author or authors.
+ * Copyright 2002-2015 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -34,8 +34,10 @@ import org.springframework.util.StringUtils;
 class PropertyPlaceholderBeanDefinitionParser extends AbstractPropertyLoadingBeanDefinitionParser {
 
 	private static final String SYSTEM_PROPERTIES_MODE_ATTRIB = "system-properties-mode";
+
 	private static final String SYSTEM_PROPERTIES_MODE_DEFAULT = "ENVIRONMENT";
 
+
 	@Override
 	protected Class<?> getBeanClass(Element element) {
 		// As of Spring 3.1, the default value of system-properties-mode has changed from
@@ -61,7 +63,11 @@ class PropertyPlaceholderBeanDefinitionParser extends AbstractPropertyLoadingBea
 		String systemPropertiesModeName = element.getAttribute(SYSTEM_PROPERTIES_MODE_ATTRIB);
 		if (StringUtils.hasLength(systemPropertiesModeName) &&
 				!systemPropertiesModeName.equals(SYSTEM_PROPERTIES_MODE_DEFAULT)) {
-			builder.addPropertyValue("systemPropertiesModeName", "SYSTEM_PROPERTIES_MODE_"+systemPropertiesModeName);
+			builder.addPropertyValue("systemPropertiesModeName", "SYSTEM_PROPERTIES_MODE_" + systemPropertiesModeName);
+		}
+
+		if (element.hasAttribute("null-value")) {
+			builder.addPropertyValue("nullValue", element.getAttribute("null-value"));
 		}
 	}
 

spring-context/src/main/resources/org/springframework/context/config/spring-context-4.2.xsd

@@ -19,7 +19,7 @@
 		]]></xsd:documentation>
 	</xsd:annotation>
 
-	<xsd:complexType name="propertyPlaceholder">
+	<xsd:complexType name="propertyLoading">
 		<xsd:attribute name="location" type="xsd:string">
 			<xsd:annotation>
 				<xsd:documentation><![CDATA[
@@ -112,7 +112,7 @@
 		</xsd:annotation>
 		<xsd:complexType>
 			<xsd:complexContent>
-				<xsd:extension base="propertyPlaceholder">
+				<xsd:extension base="propertyLoading">
 					<xsd:attribute name="system-properties-mode" default="ENVIRONMENT">
 						<xsd:annotation>
 							<xsd:documentation><![CDATA[
@@ -144,6 +144,14 @@
 							</xsd:restriction>
 						</xsd:simpleType>
 					</xsd:attribute>
+					<xsd:attribute name="null-value">
+						<xsd:annotation>
+							<xsd:documentation><![CDATA[
+	A value that should be treated as {@code null} when resolved as a placeholder value:
+	e.g. "" (empty String) or "null". By default, no such null value is defined.
+				]]></xsd:documentation>
+						</xsd:annotation>
+					</xsd:attribute>
 				</xsd:extension>
 			</xsd:complexContent>
 		</xsd:complexType>
@@ -163,7 +171,7 @@
 		</xsd:annotation>
 		<xsd:complexType>
 			<xsd:complexContent>
-				<xsd:extension base="propertyPlaceholder"/>
+				<xsd:extension base="propertyLoading"/>
 			</xsd:complexContent>
 		</xsd:complexType>
 	</xsd:element>

spring-context/src/test/java/org/springframework/context/config/ContextNamespaceHandlerTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2011 the original author or authors.
+ * Copyright 2002-2015 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -47,6 +47,7 @@ public class ContextNamespaceHandlerTests {
 		System.getProperties().remove("foo");
 	}
 
+
 	@Test
 	public void propertyPlaceholder() throws Exception {
 		ApplicationContext applicationContext = new ClassPathXmlApplicationContext(
@@ -55,7 +56,8 @@ public class ContextNamespaceHandlerTests {
 				.getBeansOfType(PlaceholderConfigurerSupport.class);
 		assertFalse("No PropertyPlaceholderConfigurer found", beans.isEmpty());
 		String s = (String) applicationContext.getBean("string");
-		assertEquals("No properties replaced", "bar", s);
+		assertEquals("bar", s);
+		assertEquals("null", applicationContext.getBean("nullString"));
 	}
 
 	@Test
@@ -68,8 +70,9 @@ public class ContextNamespaceHandlerTests {
 					.getBeansOfType(PropertyPlaceholderConfigurer.class);
 			assertFalse("No PropertyPlaceholderConfigurer found", beans.isEmpty());
 			String s = (String) applicationContext.getBean("string");
-			assertEquals("No properties replaced", "spam", s);
+			assertEquals("spam", s);
-		} finally {
+		}
+		finally {
 			if (value!=null) {
 				System.setProperty("foo", value);
 			}
@@ -87,7 +90,7 @@ public class ContextNamespaceHandlerTests {
 				.getBeansOfType(PlaceholderConfigurerSupport.class);
 		assertFalse("No PropertyPlaceholderConfigurer found", beans.isEmpty());
 		String s = (String) applicationContext.getBean("string");
-		assertEquals("No properties replaced", "spam", s);
+		assertEquals("spam", s);
 	}
 
 	@Test
@@ -98,11 +101,11 @@ public class ContextNamespaceHandlerTests {
 				.getBeansOfType(PropertyPlaceholderConfigurer.class);
 		assertFalse("No PropertyPlaceholderConfigurer found", beans.isEmpty());
 		String s = (String) applicationContext.getBean("foo");
-		assertEquals("No properties replaced", "bar", s);
+		assertEquals("bar", s);
 		s = (String) applicationContext.getBean("bar");
-		assertEquals("No properties replaced", "foo", s);
+		assertEquals("foo", s);
 		s = (String) applicationContext.getBean("spam");
-		assertEquals("No properties replaced", "maps", s);
+		assertEquals("maps", s);
 	}
 
 	@Test
@@ -113,7 +116,8 @@ public class ContextNamespaceHandlerTests {
 				.getBeansOfType(PlaceholderConfigurerSupport.class);
 		assertFalse("No PropertyPlaceholderConfigurer found", beans.isEmpty());
 		String s = (String) applicationContext.getBean("string");
-		assertEquals("Properties replaced", "${bar}", s);
+		assertEquals("${bar}", s);
+		assertEquals("null", applicationContext.getBean("nullString"));
 	}
 
 	@Test
@@ -126,6 +130,7 @@ public class ContextNamespaceHandlerTests {
 		Date date = (Date) applicationContext.getBean("date");
 		Calendar calendar = Calendar.getInstance();
 		calendar.setTime(date);
-		assertEquals("No properties overriden", 42, calendar.get(Calendar.MINUTE));
+		assertEquals(42, calendar.get(Calendar.MINUTE));
 	}
+
 }

spring-context/src/test/resources/org/springframework/context/config/contextNamespaceHandlerTests-replace-ignore.xml

@@ -1,18 +1,24 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 	   xmlns:context="http://www.springframework.org/schema/context"
-	   xmlns:util="http://www.springframework.org/schema/util" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd
+	   xmlns:util="http://www.springframework.org/schema/util"
-				http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.1.xsd
+	   xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.2.xsd
-				http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-2.5.xsd">
+				http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.2.xsd
+				http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-4.2.xsd">
 
 	<util:properties id="placeholderProps">
 		<prop key="foo">bar</prop>
+		<prop key="baz"></prop>
 	</util:properties>
 
-	<context:property-placeholder properties-ref="placeholderProps" ignore-unresolvable="true"/>
+	<context:property-placeholder properties-ref="placeholderProps" ignore-unresolvable="true" null-value=""/>
 
 	<bean id="string" class="java.lang.String">
 		<constructor-arg value="${bar}"/>
 	</bean>
 
+	<bean id="nullString" class="java.lang.String" factory-method="valueOf">
+		<constructor-arg type="java.lang.Object" value="${baz}"/>
+	</bean>
+
 </beans>

spring-context/src/test/resources/org/springframework/context/config/contextNamespaceHandlerTests-replace.xml

@@ -1,17 +1,19 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 	   xmlns:context="http://www.springframework.org/schema/context"
-	   xmlns:util="http://www.springframework.org/schema/util" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd
+	   xmlns:util="http://www.springframework.org/schema/util"
-				http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.1.xsd
+	   xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.2.xsd
-				http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-2.5.xsd">
+				http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.2.xsd
+				http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-4.2.xsd">
 
 	<util:properties id="placeholderProps">
 		<prop key="foo">bar</prop>
+		<prop key="bar">MYNULL</prop>
 	</util:properties>
 
 	<util:properties id="emptyProps"/>
 
-	<context:property-placeholder  properties-ref="placeholderProps" order="2"/>
+	<context:property-placeholder properties-ref="placeholderProps" order="2" null-value="MYNULL"/>
 
 	<context:property-placeholder properties-ref="emptyProps" order="1" ignore-unresolvable="true"/>
 
@@ -21,4 +23,8 @@
 		<constructor-arg value="${foo}"/>
 	</bean>
 
+	<bean id="nullString" class="java.lang.String" factory-method="valueOf">
+		<constructor-arg type="java.lang.Object" value="${bar}"/>
+	</bean>
+
 </beans>