SpringFramework之DI

简介

在创建对象的过程中Spring可以依据配置对象的属性进行设置，这个过程称之为依赖注入。

注入方式

        属性setter注入

public interface UserService {
    public void way();
}

public interface UserDao {
    public void way();
}

public class UserServiceImpl implements UserService {
    private UserDao userDao;
    
    public void setUserDao(UserDao userDao) {
        this.userDao= userDao;
    }
    
    @Override
    public void way() {
        userDao.way(); 
    }
}

        构造方法注入

public class UserServiceImpl implements UserService {
    private UserDao userDao;
    
    public UserServiceImpl (UserDao userDao) {
        this.userDao= userDao;
    }
    
    @Override
    public void way() {
        userDao.way(); 
    }
}

        自动装配

public class UserServiceImpl implements UserService {
    //byName：通过名字自动装在,setXXX的名字
    //byType：通过类型自动装载
    @Autowired
    private UserDao userDao; 

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