Mybatis入门之增删改查(CRUD)

整体代码架构

项目代码下载
使用Mybatis，需要导入 mybatis-3.2.7.jar mysql-jdbc.jar

数据库

CREATE DATABASE `mybatis` ;
USE `mybatis`;
DROP TABLE IF EXISTS `users`;
CREATE TABLE `users` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `NAME` varchar(20) DEFAULT NULL,
  `age` int(11) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=MyISAM AUTO_INCREMENT=21 DEFAULT CHARSET=utf8;
insert  into `users`(`id`,`NAME`,`age`) values (1,'阿星',11),(2,'阿黄',27),(3,'阿华',23);

配置文件 mybatis.conf.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN" "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC" />
            <!-- 配置数据库连接信息 -->
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.jdbc.Driver" />
                <property name="url" value="jdbc:mysql://localhost:3306/mybatis" />
                <property name="username" value="root" />
                <property name="password" value="root" />
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="com/mybatis/mapping/userMapper.xml"/>
    </mappers>
</configuration>

service 具体实现增删改查

package com.mybatis.service;

import java.util.List;

import org.apache.ibatis.session.SqlSession;

import com.mybatis.bean.User;
import com.mybatis.utils.DbUtils;

public class UserService {

    public static SqlSession  getSession(){
        return DbUtils.getSession();
    }

    public static void getUserById(int id){
        String statement = "com.mybatis.mapping.userMapper.getUser";
        System.out.println("select");
        User user = getSession().selectOne(statement,id);
        System.out.println(user);
    }

    public static void getUserAll(){
        String statement = "com.mybatis.mapping.userMapper.getUserAll";
        List<User> list = getSession().selectList(statement);
        System.out.println(list.toString());
    }
    public static User getLastUser(){
        String statement = "com.mybatis.mapping.userMapper.getLastUser";
        User user = getSession().selectOne(statement);
        //System.out.println(list.toString());
        System.out.println(user);
    //  return list.get(0);
        return user;
    }
    public static void update(User user){
        System.out.println("update "+user.toString());
        String statement = "com.mybatis.mapping.userMapper.updateUser";
        getSession().update(statement, user);
    }

    public static void delUserById(int id){
        System.out.println("del id ="+id);
        String statement = "com.mybatis.mapping.userMapper.deleteUser";
        getSession().delete(statement, id);
    }

    public static void insertUser(User user){
        String statement = "com.mybatis.mapping.userMapper.insertUser";
        getSession().insert(statement, user);

    }
}

数据库连接

package com.mybatis.utils;

import java.io.InputStream;

import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

import com.mybatis.test.Test;

public class DbUtils {
    private static SqlSessionFactory sessionFactory;
    static {
        try{
        String resource = "mybatis.conf.xml";
        InputStream is = Test.class.getClassLoader().getResourceAsStream(resource);
        sessionFactory = new SqlSessionFactoryBuilder().build(is);
        }catch(Exception  e){
              e.printStackTrace();
        }
    }

    public static SqlSession getSession(){
        return sessionFactory.openSession();
    }
}

测试增删改查

package com.mybatis.test;

import java.io.IOException;

import com.mybatis.bean.User;
import com.mybatis.service.UserService;

public class Test {
    public static void main(String[] args) throws IOException {
        //insert
        User userAdd = new User();
        userAdd.setAge(50);
        userAdd.setName("阿华");
        UserService.insertUser(userAdd);

        //select
        UserService.getUserById(1);
        UserService.getUserAll();

        //update
        User userUpdate = UserService.getLastUser();
        userUpdate.setName("阿星");
        userUpdate.setAge(11);
        UserService.update(userUpdate);

        //delete
        User userDel = UserService.getLastUser();
        UserService.delUserById(userDel.getId());
        UserService.getLastUser();
    }
}

xml mapping

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">


<mapper namespace="com.mybatis.mapping.userMapper" >
    <select id="getUser" parameterType="int"  resultType="com.mybatis.bean.User">
        select * from users where id=#{id}
    </select>

    <select id="getUserAll" resultType="com.mybatis.bean.User">
        SELECT * FROM users 
    </select>
      <select id="getLastUser" resultType="com.mybatis.bean.User">
        SELECT * FROM users ORDER BY id DESC LIMIT 1
    </select>  

       <update id="updateUser" parameterType="com.mybatis.bean.User">
        UPDATE  users SET NAME = #{name}, age = #{age} WHERE id = #{id};
    </update>
    <insert id="insertUser" parameterType="com.mybatis.bean.User">
        INSERT INTO users (id, NAME, age) VALUES (#{id}, #{name}, #{age}) ;
    </insert>

        <delete id="deleteUser" parameterType="int">
            DELETE 
            FROM
              users 
            WHERE id = #{id} ;
        </delete>
</mapper>

实体类

package com.mybatis.bean;

public class User {

    private int id;
    private String name;
    private int age;

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    @Override
    public String toString() {
        return "User bean {id=" + id + ", name=" + name + ", age=" + age + "}";
    }
}