答案：

Question

由于某种原因，我试图用@Autowired实例化的对象指针永远不会被实例化。我试过看几个例子，但似乎什么都没有用！这是我的代码：

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中

<?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>

我有什么想法我做错了吗？

答案：

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中

<?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

试试这个：

@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只适用于春豆。

Answer 2

您的对象不是Spring bean，因为您自己创建它。

您没有任何代码来初始化您的applicationContext。 @ContextConfiguration，AFAIK，仅用于单元测试。

Spring并不神奇，你需要在它运行之前调用它。

如果你使用main方法，你需要自己创建你的applicationContext，然后从中获取你的bean。

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

Answer 3

bean只会被注入到spring管理的实例中。由于您使用Testing运算符创建了new的实例，因此不会注入integrationRestService。

你可以做的是

从应用程序上下文中获取testing的实例。

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

在Testing类上使用@Configurable注释，以便使用new运算符创建的实例也将进行弹簧管理。但这是一个非常麻烦的过程。

Answer 4

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

做得好！

但是，请使用

@Autowired
private Testing testing;

失败了。

为什么我的变量不能自动装配？

答案：

4 个答案: