Spring基于的注解自动装配和依赖注入（***）

#自动装配的小Demo:

package com.gyf.annotation;

//DAO层
public interface UserDao {
    public void save();
}


package com.gyf.annotation;

import org.springframework.stereotype.Repository;

@Repository("userDao")
public class UserDaoImpl implements UserDao {
    @Override
    public void save() {
        System.out.println("UserDao接口的实现类的save方法的实现...");
    }
}


//业务层
package com.gyf.annotation;

public interface UserService {
     void save();
}


package com.gyf.annotation;

import org.springframework.stereotype.Service;

import javax.annotation.Resource;

@Service("userService")
public class UserServiceImpl implements UserService {
    @Resource(name = "userDao")
    private UserDao userDao;
    @Override
    public void save() {
        this.userDao.save();
        System.out.println("userservice...save...");
    }
}

//控制层

package com.gyf.annotation;

import org.springframework.stereotype.Controller;

import javax.annotation.Resource;

@Controller("userController")
public class UserController {
    @Resource(name="userService")
    private UserService userService;
    public void save(){
        this.userService.save();
        System.out.println("userController...save...");
    }
}

说明： 

无论是servlet、JSP，还是ssm都是用的mvc的设计思想；

 Dao层与数据库相关联，业务层并调用DAO层的变量，并进行中间逻辑处理，控制层

对业务层进行调用，并进行进一步的逻辑控制，包括字符编码的设置等。

#配置文件：

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       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">


   <context:component-scan base-package="com.gyf.annotation"/>
</beans>

package com.gyf.test;

import com.gyf.annotation.UserController;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class test {
    public static void main(String[] args) {
        String xmlPath="beans6.xml";
        ApplicationContext ac=new ClassPathXmlApplicationContext(xmlPath);
        UserController userController=(UserController)ac.getBean("userController");
        userController.save();
    }
}

----------------------------------------------------------------------------------------------------------------------------------------------

#依赖注入

//DAO层
package com.gyf.ioc;

public interface UserDao {
      void say();
}

package com.gyf.ioc;

public class UserDaoImpl implements UserDao {

    @Override
    public void say() {
        System.out.println("userDao say hello world");
    }

}

//业务层
package com.gyf.ioc;

public interface UserService {
      void say();
}


package com.gyf.ioc;

public class UserServiceImpl implements UserService {
    private UserDao userDao;

    public void setUserDao(UserDao userDao) {
        this.userDao = userDao;
    }

    @Override
    public void say() {
        this.userDao.say();
        System.out.println("userService say hello world");
    }
}

#配置文件<?xml version="1.0" encoding="UTF-8"?>

<beans xmlns="http://www.springframework.org/schema/beans"
       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">

      <bean id="userDao" class="com.gyf.ioc.UserDaoImpl"/>

       <bean id="userService" class="com.gyf.ioc.UserServiceImpl">
             <!--将DAO层的数据注入到业务层，说明该方法是set方法进行注入到业务层组件中-->

             <property name="userDao" ref="userDao"/>
       </bean>
    
</beans>

#测试：

package com.gyf.test;

import com.gyf.ioc.UserDao;
import com.gyf.ioc.UserService;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class test {
    @Test
    public void test1(){
        ApplicationContext ac=new ClassPathXmlApplicationContext("beansIOC.xml");

        UserDao userDao=(UserDao)ac.getBean("userDao");
        userDao.say();
        UserService userService=(UserService)ac.getBean("userService");
        userService.say();
    }
}

 学会重复！

多练习，Spring 基础很重要！

这个有点类似于多态的运用，以及变量的调用；