为什么我的变量不能自动装配？

Question

For some reason the object pointer I am trying to instantiate with @Autowired is never instantiated. I've tried looking at several examples, but nothing seems to work! Here is my code:

Testing.java

package com.example.core.service.integration;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.test.context.ContextConfiguration;

@ContextConfiguration(locations={"/app-context.xml"})
public class Testing {

@Autowired
private IntegrationRestService integrationRestService;

public static void main(String args[])  {
    Testing t = new Testing();
    t.checkNull();
}

private void checkNull() {
    if(integrationRestService == null) System.err.println("FAIL...");
    else System.out.println("SUCCESS!");
}

}

IntegrationTestService.java

public interface IntegrationRestService {

public  FindSomething getFindSomethingResponse(String a, int b, int c);

public  FindSomethingElse getFindSomethingElseResponse(String urlToRead);
}

IntegrationRestServiceImpl.java

@Service
@Path("/test")
public class IntegrationRestServiceImpl implements IntegrationRestService {


    public IntegrationRestServiceImpl() {
        super();
     }
   ...
}

app-context.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:mvc="http://www.springframework.org/schema/mvc"     xmlns:p="http://www.springframework.org/schema/p"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context"
default-autowire="constructor"
xsi:schemaLocation="
    http://www.springframework.org/schema/beans 
    http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
    http://www.springframework.org/schema/mvc
    http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd
    http://www.springframework.org/schema/context
    http://www.springframework.org/schema/context/spring-context.xsd">


<!-- JSR-303 support will be detected on classpath and enabled automatically -->
<context:annotation-config/>

<context:component-scan base-package="com.example.core"/>


<bean id="IntegrationRestService" class="com.example.core.service.integration.IntegrationRestServiceImpl" />
<bean id="Testing" class="com.example.core.service.integration.Testing" />

</beans>

Any ideas what on I'm doing wrong?

Answer:

Testing.java

@Service
public class Testing {

@Autowired
private IntegrationRestService integrationRestService;

public static void main(String args[])  {
    ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("/META-INF/spring/app-context.xml");
    Testing testing = (Testing) context.getBean(Testing.class);
    testing.checkNull();
}


private void checkNull() {
    if(integrationRestService == null) System.err.println("FAIL...");
    else System.out.println("SUCCESS!");
}

}

app-context.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:mvc="http://www.springframework.org/schema/mvc" xmlns:p="http://www.springframework.org/schema/p"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context"
default-autowire="constructor"
xsi:schemaLocation="
    http://www.springframework.org/schema/beans 
    http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
    http://www.springframework.org/schema/mvc
    http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd
    http://www.springframework.org/schema/context
    http://www.springframework.org/schema/context/spring-context.xsd">


<!-- JSR-303 support will be detected on classpath and enabled automatically -->
<context:annotation-config/>

<context:component-scan base-package="com.example.core"/>

<bean id="testing" class="com.example.core.service.integration.Testing"/>

<bean id="integrationRestService" class="com.example.core.service.integration.IntegrationRestServiceImpl" />

</beans>

Answer 1

Try this:

@Service
public class Testing {

@Autowired
private IntegrationRestService integrationRestService;

public static void main(String args[])  {
    final AbstractApplicationContext context = new ClassPathXmlApplicationContext("/app-context.xml");
    Testing t = context.getBean(Testing.class);
    t.checkNull();
}

private void checkNull() {
    if(integrationRestService == null) System.err.println("FAIL...");
    else System.out.println("SUCCESS!");
}

}

@Autowired works just with spring beans.

Answer 2

Your object is not a Spring bean, since you're creating it yourself.

You don't have any code to initialize your applicationContext. @ContextConfiguration , AFAIK, is only used for unit testing.

Spring is not magical, you need to invoke it before it works.

If you use a main method, you need to create your applicationContext yourself, then get your bean from it.

ApplicationContext ctx = new ClasspathXmlApplicationContext("/app-context.xml");
Testing testing = (Testing) ctx.getBean("testing");

Answer 3

The beans will get injected only into spring-managed instances. Since you are creating an instance of Testing using the new operator, it won't get the integrationRestService injected.

what you can do is

• Get the instance of testing from the application context.

   ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("Spring.xml"); Testing testing = (Testing) context.getBean(Testing.class); 

• Use the @Configurable annotation on Testing class so that instances created using new operator will also be spring managed. But this is quite a cumbersome process.

Answer 4

ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("Spring.xml");
Testing testing = (Testing) context.getBean(Testing.class);

is well done!

but,use

@Autowired
private Testing testing;

is fail.