spring注解

Spring注解

1.配置context命名空间

<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
                           http://www.springframework.org/schema/beans/spring-beans.xsd
                           http://www.springframework.org/schema/context
                           http://www.springframework.org/schema/context/spring-context.xsd
">

2.配置让Spring扫描类与支持注解

<context:component-scan base-package="com.lty._05anno"></context:component-scan>

3.在相应的类上加注解

• @Controller：控制层
• @Service：业务层
• @Repository：持久层
• @Component:组件(一个bean不知道在哪一层用这个)
• @Autowired:注入功能

4.解决接口有多个实现

▪ 先类型注入，再根据名称注入

@Service
public class UserServiceImpl implements IUserService {
    /*注解的bean有默认名称,实现类名称首字母小写*/
    @Autowired
    IUserDao userDaoJDBCImpl;
}

▪ 修改bean的名称

@Repository("userDaoJDBC")
public class UserDaoJDBCImpl implements IUserDao{

    @Override
    public void save() {
        System.out.println("UserDaoJDBCImpl : save");
    }
}
@Autowired
    IUserDao userDaoJDBC;
}

▪ 在注入bean的时候加上一个限定注解

@Service
public class UserServiceImpl implements IUserService {
    @Autowired
    @Qualifier("userDaoJDBC")
    IUserDao userDaoJDBCImpl;
}

▪ 使用@Resource

@Service
public class UserServiceImpl implements IUserService {
    @Resource(name = "userDaoJDBCImpl")
    IUserDao userDao;
}