@ContextHierarchy is a class-level annotation that is used to define a hierarchy of contexts using a list of @ContextConfiguration instances, each of which defines a level in the context hierarchy. In this article we will see different ways of establishing application context hierarchy using @ContextHierarchy. We will also see how to inherit, merge or override an existing context.
Single Context
Let’s first define single ApplicationContext.
SpringSingleContext:
package com.javarticles.spring;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.test.context.ContextConfiguration;
@ContextConfiguration(locations = "/context1.xml")
public class SpringSingleContext {
@Autowired
BeanA beanA;
}
context1.xml:
<?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd"> <bean id="beanA" class="com.javarticles.spring.BeanA" /> </beans>
Define Context hierarchy
We extend SpringSingleContext and define multiple contexts using @ContextHierarchy. It now consists of three levels, first one is for context1.xml, the second one is for context2.xml and third one is for context3.xml.
context2.xml:
<?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd"> <bean id="beanB" class="com.javarticles.spring.BeanB" /> </beans>
context3.xml:
<?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd"> <bean id="beanC" class="com.javarticles.spring.BeanC" /> </beans>
SpringMultipleContextsExample:
package com.javarticles.spring;
import static org.junit.Assert.*;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.ApplicationContext;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.ContextHierarchy;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
@RunWith(SpringJUnit4ClassRunner.class)
@ContextHierarchy({
@ContextConfiguration("/com/javarticles/spring/context2.xml"),
@ContextConfiguration("/com/javarticles/spring/context3.xml") })
public class SpringMultipleContextsExample extends SpringSingleContext {
@Autowired
private BeanB beanB;
@Autowired
private BeanC beanC;
@Autowired
private ApplicationContext context;
@Test
public void verifyBeans() {
assertNotNull(beanA);
assertNotNull(beanB);
assertNotNull(beanC);
}
@Test
public void printAllContexts() {
System.out.println("Print contexts " + context);
ApplicationContext parent = context;
while (parent != null) {
System.out.println("Context: " + parent.getId());
System.out.println("[");
for (String beanName : parent.getBeanDefinitionNames()) {
if (beanName.contains("bean")) {
System.out.println(beanName);
}
}
System.out.println("]");
parent = parent.getParent();
}
}
}
Output:
Print contexts [email protected]cf57e3: startup date [Sun Feb 07 23:15:22 IST 2016]; parent: [email protected]e6e9c3 Context: [email protected]cf57e3 [ beanC ] Context: [email protected]e6e9c3 [ beanB ] Context: [email protected]56dfcb [ beanA ]
Inherit context hierarchy using @ContextHierarchy
In the below test class, we have defined two contexts, a parent and a child. We have given names to each context, parent is context1 and child is context2.
The ApplicationContext is autowired using @Autowired annotation. If there are multiple contexts, the test instance is autowired with one of the lowest context in the hierarchy. In our case, it should be the context2.
SpringBaseContextHierarchy:
package com.javarticles.spring;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.ApplicationContext;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.ContextHierarchy;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
@RunWith(SpringJUnit4ClassRunner.class)
@ContextHierarchy({
@ContextConfiguration(name="context1", locations = "/context1.xml"),
@ContextConfiguration(name="context2", locations = "/com/javarticles/spring/context2.xml")})
public class SpringBaseContextHierarchy {
@Autowired
ApplicationContext context;
@Test
public void printAllContexts() {
System.out.println("Print contexts " + context);
ApplicationContext parent = context;
while (parent != null) {
System.out.println("Context: " + parent.getId());
System.out.println("[");
for (String beanName : parent.getBeanDefinitionNames()) {
if (beanName.contains("bean")) {
System.out.println(beanName);
}
}
System.out.println("]");
parent = parent.getParent();
}
}
}
context1.xml:
<?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd"> <bean id="beanA" class="com.javarticles.spring.BeanA" /> </beans>
context2.xml:
<?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd"> <bean id="beanB" class="com.javarticles.spring.BeanB" /> </beans>
You can see from the output, the context autowired is the context2.
Output:
Print contexts [email protected]24753a: startup date [Sun Feb 07 22:39:35 IST 2016]; parent: [email protected]a485d2 Context: [email protected]24753a [ beanB ] Context: [email protected]a485d2 [ beanA ]
We will next inherit this test class to further add new application contexts. We have added a new context context3. If you notice, we have added a new context XML to an existing context context1. By default, the new XML will added to the existing context instead of creating a new application context.
SpringInheritContextExample:
package com.javarticles.spring;
import static org.junit.Assert.assertFalse;
import static org.junit.Assert.assertNotNull;
import static org.junit.Assert.assertTrue;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.ContextHierarchy;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
@RunWith(SpringJUnit4ClassRunner.class)
@ContextHierarchy({
@ContextConfiguration(name = "context1", locations = "/com/javarticles/spring/context4.xml"),
@ContextConfiguration(name = "context3", locations = "/com/javarticles/spring/context3.xml") })
public class SpringInheritContextExample extends SpringBaseContextHierarchy {
@Autowired
private BeanC beanC;
@Test
public void beanADetails() {
assertFalse(context.containsBeanDefinition("beanA"));
assertTrue(context.getParent().containsBean("beanA"));
System.out.println("Instance of beanA: " + context.getBean("beanA"));
}
@Test
public void verifyBeans() {
assertNotNull(context.getBean("beanB"));
assertNotNull(context.getBean("beanC"));
assertNotNull(context.getBean("beanD"));
}
}
Here are the context files.
context3.xml:
<?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd"> <bean id="beanC" class="com.javarticles.spring.BeanC" /> </beans>
context4.xml:
<?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd"> <bean id="beanD" class="com.javarticles.spring.BeanD" /> <bean id="beanA" class="com.javarticles.spring.OverridenBeanA" /> </beans>
When you run the test class, you can see from the output that the context2 now has two beans BeanA and BeanD. Also a new child context has been added.
Output:
Instance of beanA: [email protected] Print contexts [email protected]f6480: startup date [Mon Feb 08 08:44:03 IST 2016]; parent: [email protected]c7c2a6 Context: [email protected]f6480 [ beanC ] Context: [email protected]c7c2a6 [ beanB ] Context: [email protected]7c004 [ beanA beanD ]
Override context using @ContextHierarchy
Let’s now override context1 with the following context XML.
overrideContext.xml:
<?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd"> <bean id="beanD" class="com.javarticles.spring.BeanD" /> </beans>
In order to override a context set @ContextConfiguration‘s attribute inheritLocations to false.
SpringOverrideContextExample:
package com.javarticles.spring;
import static org.junit.Assert.assertFalse;
import static org.junit.Assert.assertNotNull;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.ContextHierarchy;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
@RunWith(SpringJUnit4ClassRunner.class)
@ContextHierarchy({
@ContextConfiguration(name = "context1",
locations = "/com/javarticles/spring/overrideContext.xml",
inheritLocations = false),
@ContextConfiguration(name = "context3", locations = "/com/javarticles/spring/context3.xml") })
public class SpringOverrideContextExample extends SpringBaseContextHierarchy {
@Autowired
private BeanC beanC;
@Test
public void beanAShouldntExist() {
assertFalse(context.containsBean("beanA"));
}
@Test
public void verifyBeans() {
assertNotNull(context.getBean("beanB"));
assertNotNull(context.getBean("beanC"));
assertNotNull(context.getBean("beanD"));
}
}
Output:
Print contexts [email protected]adae5d: startup date [Mon Feb 08 08:59:27 IST 2016]; parent: [email protected]09711b Context: [email protected]fadae5d [ beanC ] Context: [email protected]09711b [ beanB ] Context: [email protected]c7c2a6 [ beanD ]
If inheritLocations is set to true, output will be different.
Output:
Print contexts [email protected]f6480: startup date [Mon Feb 08 09:01:32 IST 2016]; parent: [email protected]c7c2a6 Context: [email protected]f6480 [ beanC ] Context: [email protected]c7c2a6 [ beanB ] Context: [email protected]7c004 [ beanA beanD ]
Download the source code
This was an example about using spring @ContextHierarchy to create hierarchy of contexts.
You can download the source code here: springContextHierarchyAnnotationExample.zip
