Spring注解报出 ‘java.lang.NullPointerException ’错误

宋徽柔 2016-05-05 05:19:31

这个是异常错误图片，希望各位大神帮忙看看，小弟不胜感激，谢谢....

下面是所有的代码
-------------------------------------------------------------------------UserDao代码
package com.asiainfo.dao;
public interface UserDao {
public void addUser();
}

-------------------------------------------------------------------------UserDaoImpl 代码
package com.asiainfo.dao;
import org.springframework.stereotype.Repository;
@Repository(value="userDao")
public class UserDaoImpl implements UserDao {

@Override
public void addUser() {
System.out.println("UserDaoImpl---------------------------addUser");
}

}

-------------------------------------------------------------------------UserService 代码
package com.asiainfo.interfaces;
public interface UserService {
public void addUser();
}

-------------------------------------------------------------------------UserServiceImpl 代码
package com.asiainfo.impl;
import javax.annotation.Resource;
import org.springframework.stereotype.Service;
import com.asiainfo.dao.UserDao;
import com.asiainfo.interfaces.UserService;
@Service(value="userService")
public class UserServiceImpl implements UserService {

@Resource(name="userDao")
private UserDao userDao = null;

@Override
public void addUser() {
userDao.addUser();
}

}

-------------------------------------------------------------------------TestUserService 代码
package com.asiainfo.test;
import javax.annotation.Resource;
import org.junit.Test;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
import com.asiainfo.interfaces.UserService;
@ContextConfiguration(locations="classpath:applicationContext.xml")
public class TestUserService {
@Resource(name="userService")
private UserService userService = null;

@Test
public void testAddUser(){
userService.addUser();
}
}

-------------------------------------------------------------------------applicationContext.xml代码
<?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"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-2.5.xsd
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-2.5.xsd">

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

</beans>

...全文