1.建立一个实体类，建立一个dao类

package com.sun.model;public class User {    private String username;    private String password;    public String getUsername() {        return username;    }    public void setUsername(String username) {        this.username = username;    }    public String getPassword() {        return password;    }    public void setPassword(String password) {        this.password = password;    }    }

package com.sun.dao;import com.sun.model.User;public class UserDAO {        public void save(User u) {        System.out.println("saved");    }}

2.将user存入数据库，一般的情况是数据库连接，然后session.save(user);但是有了service这一层，就将这句话给封装了，变成了service.save（u），我们不再接触数据库那一层了。

package com.sun.service;import com.sun.dao.UserDAO;import com.sun.model.User;public class UserService {    private UserDAO userdao;            public UserDAO getUserdao() {        return userdao;    }    public void setUserdao(UserDAO userdao) {        this.userdao = userdao;    }    public void add(User u) {        this.userdao.save(u);            }}

package com.sun.service;import com.sun.dao.UserDAO;import com.sun.model.User;public class Test {        public static void main(String[] args) {            UserService service=new UserService();            UserDAO userdao=new UserDAO();            service.setUserdao(userdao);            User u=new User();            service.add(u);        }    }

3.将service.add(u);与userdao.save(u);比较就知道service的大致作用了

4.需要的spring jar包

 

 

5.写一个程序测试(spring 的作用就是你现在还不用new 一个service了，它来帮你完成即控制反转的含义)

6.service代码

package com.sun.spring;public interface UserService {    public void addUser();}

package com.sun.spring;public class serviceimpl implements UserService {    public void addUser() {        System.out.println("hello");            }}

 

7.加入.xml文件，文件帮助内容在下面找

8.配置xml文件

9.测试

package com.sun.spring;import org.springframework.context.ApplicationContext;import org.springframework.context.support.ClassPathXmlApplicationContext;public class Test {    public static void main(String[] agrs) {        String xmlPath="com/sun/spring/beans.xml";        ApplicationContext appicationcantext=new ClassPathXmlApplicationContext(xmlPath);        UserService userservice=(UserService) appicationcantext.getBean("userService");        userservice.addUser();    }}

10.spring就是帮你管类文件的，所有你需要new的它都帮你用配置文件统一完成。