@Autowired来的spring 下的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其内的@autowired的bean
-
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
< bean >id=“personServiceImpl” class=“com.machome.testtip.impl.PersonServiceImpl” < /bean>
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<String> 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