xml配置文件

main文件

public static void main(String[] args) throws SQLException {				ApplicationContext ctx = new ClassPathXmlApplicationContext("applicationContext.xml");				UserController userController = (UserController) ctx.getBean("userController");		userController.excute();					}

controller文件

@Controllerpublic class UserController {		@Autowired	private UserService userService;		public void excute() {		System.out.println("UserController excute...");		userService.add();	}}

service文件

@Servicepublic class UserService {		@Autowired	private UserRepository userRepository;		public void add() {		System.out.println("UserService add...");		userRepository.save();	}}

接口文件

public interface UserRepository {		public void save();}

接口实现层文件

@Repositorypublic class UserRepositoryImpl implements UserRepository {	@Override	public void save() {		System.out.println("UserRepository Save...");	}}

利用@Autowired注解实现bean与bean之间的联系，上述main方法输出

UserController excute...UserService add...UserRepository Save...

二、IOC没有装配的bean

//@Componentpublic class TestObject {		public void name() {		System.out.println("TestObject ...");	}}

这个bean没有加上@Component注解，因此ioc容器不会加载它，但是又需要用到它，则需进行如下处理

@Repositorypublic class UserRepositoryImpl implements UserRepository {	//设置required=false	@Autowired(required=false)	private TestObject testObject;		@Override	public void save() {		System.out.println("UserRepository Save...");		System.out.println(testObject);	}}

三、指定唯一bean

@Repositorypublic class UserJdbcRepositoryImpl implements UserRepository{	@Override	public void save() {		System.out.println("UserJdbcRepositoryImpl save...");	}}

如下代码就不知道该调用哪个实现类的save方法

@Servicepublic class UserService {		@Autowired	private UserRepository userRepository;		public void add() {		System.out.println("UserService add...");		//这里不知道调用哪个实现类的save方法		userRepository.save();	}}

为了指定调用哪个save方法，则需要指定实现接口的哪个类，修改如下

@Servicepublic class UserService {		@Autowired	@Qualifier("userJdbcRepositoryImpl")	private UserRepository userRepository;		public void add() {		System.out.println("UserService add...");		//这里指定了实现类UserJdbcRepositoryImpl		userRepository.save();	}}