@Autowired注入Spring Bean，则当前类必须也是Spring Bean才能调用它，不能用new xxx()来获得对象，这种方式获得的对象无法调用@Autowired注入的Bean。

1、类1，加入Spring Pool

public class PersonServiceImpl implements PersonService{    public void save(){        System.out.println("This is save for test spring");    }    public List
     
       findAll(){        List
      
        retList = new ArrayList
       
        ();        for(int i=1;i<10;i++){            retList.add("test"+i);        }        return retList;            }}//加入Spring Pool
                
        
       
      
     

2、类2，@Autowired类1，并且也加入Spring Pool

public class ProxyPServiceImpl implements ProxyPService {       public void save(){        System.out.print("this is proxy say:");        personService.save();    }    public List
     
       findAll(){        System.out.print("this is proxy say:");        return personService.findAll();    }        @Autowired    PersonService personService;   }
     

3、直接new类2，则执行其方法时出null pointer错误

ProxyPService  proxyPService = new ProxyPServiceImpl();proxyPService.save();执行报错:java.lang.NullPointerException    at com.machome.testtip.impl.ProxyPServiceImpl.save(ProxyPServiceImpl.java:18)    at com.machome.testtip.TestSpring2.testSave(TestSpring2.java:34)    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)

4、解决：用Spring方式获取类2的Bean，再执行其方法，没问题

ProxyPService  proxyPService = null;try {                String[] confFile = {"spring.xml"};                ctx = new ClassPathXmlApplicationContext(confFile);                proxyPService = (ProxyPService)ctx.getBean("ProxyPServiceImpl");} catch (Exception e) {                e.printStackTrace();}proxyPService.save();执行:this is proxy say:This is save for test spring

 

参考：