MyBatis Demo

時間 2019-11-16

標籤 mybatis demo 欄目 MyBatis 简体版

原文原文鏈接

什麼是 MyBatis？html

MyBatis 是支持普通 SQL 查詢，存儲過程和高級映射的優秀持久層框架。 MyBatis 消除了幾乎全部的 JDBC 代碼和參數的手工設置以及對結果集的檢索。MyBatis 能夠使用簡單的XML 或註解用於配置和原始映射，將接口和 Java 的 POJO（Plain Old Java Objects，普通的Java對象）映射成數據庫中的記錄。java

MyBatis下載：https://github.com/mybatis/mybatis-3/releasesmysql

Mybatis實例git

對一個User表的CRUD操做：github

User表：sql

-- ----------------------------
-- Table structure for `user`
-- ----------------------------
DROP TABLE IF EXISTS `users`;
CREATE TABLE `users` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `userName` varchar(50) DEFAULT NULL,
  `userAge` int(11) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=6 DEFAULT CHARSET=utf8;

-- ----------------------------
-- Records of user
-- ----------------------------
INSERT INTO `user` VALUES ('1', 'summer', '30');
INSERT INTO `user` VALUES ('2', 'test2', '22');

在Src目錄下建一個mybatis的xml配置文件config.xml數據庫

<?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" />
            <!-- 配置數據庫鏈接信息 -->
            <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="zy19940701" />
            </dataSource>
        </environment>
    </environments>
    
    <mappers>
        <!-- 註冊userMapper.xml文件， 
        userMapper.xml位於me.gacl.mapping這個包下，因此resource寫成me/gacl/mapping/userMapper.xml-->
        <mapper resource="com/zy/mapping/userMapper.xml"/>
    </mappers>
    
</configuration>

定義User mappers的userMapper.xml配置文件apache

<?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">
<!-- 爲這個mapper指定一個惟一的namespace，namespace的值習慣上設置成包名+sql映射文件名，這樣就可以保證namespace的值是惟一的
例如namespace="me.gacl.mapping.userMapper"就是me.gacl.mapping(包名)+userMapper(userMapper.xml文件去除後綴)
 -->
<mapper namespace="com.zy.mapping.userMapper">
    <!-- 在select標籤中編寫查詢的SQL語句， 設置select標籤的id屬性爲getUser，id屬性值必須是惟一的，不可以重複
    使用parameterType屬性指明查詢時使用的參數類型，resultType屬性指明查詢返回的結果集類型
    resultType="me.gacl.domain.User"就表示將查詢結果封裝成一個User類的對象返回
    User類就是users表所對應的實體類
    -->
    <!-- 
        根據id查詢獲得一個user對象
     -->
    <select id="getUser" parameterType="int" 
        resultType="com.zy.domain.User">
        select * from users where id=#{id}
    </select>
    <!-- 
        新增user對象
     -->
    <insert id="addUser" parameterType="com.zy.domain.User" 
        useGeneratedKeys="true" keyProperty="id"> 
        insert into users(name,age)  
             values(#{name},#{age})  
    </insert>
    <!-- 
        更新user對象
     -->
    <update id="updateUser" parameterType="com.zy.domain.User"> 
        update users set name=#{name},age=#{age} 
        where id=#{id}  
    </update>
    <!-- 
        刪除user對象
     -->
    <update id="deleteUser" parameterType="com.zy.domain.User"> 
        delete from users where id=#{id}  
    </update>
</mapper>

Users類的定義：session

package com.zy.domain;

/**
 * @author gacl
 * users表所對應的實體類
 */
public class User {

    //實體類的屬性和表的字段名稱一一對應
    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 [id=" + id + ", name=" + name + ", age=" + age + "]";
    }
}

測試類Test：mybatis

package com.zy.test;

import java.io.IOException;
import java.io.InputStream;
import java.io.Reader;
import com.zy.domain.User;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

public class Test1 {

    public static void main(String[] args) throws IOException {
        //mybatis的配置文件
        String resource = "config.xml";
        //使用類加載器加載mybatis的配置文件（它也加載關聯的映射文件）
        InputStream is = Test1.class.getClassLoader().getResourceAsStream(resource);
        //構建sqlSession的工廠
        SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(is);
        //使用MyBatis提供的Resources類加載mybatis的配置文件（它也加載關聯的映射文件）
        //Reader reader = Resources.getResourceAsReader(resource); 
        //構建sqlSession的工廠
        //SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(reader);
        //建立能執行映射文件中sql的sqlSession
        SqlSession session = sessionFactory.openSession();
        /**
         * 映射sql的標識字符串，
         * me.gacl.mapping.userMapper是userMapper.xml文件中mapper標籤的namespace屬性的值，
         * getUser是select標籤的id屬性值，經過select標籤的id屬性值就能夠找到要執行的SQL
         */
        /*String statement = "com.zy.mapping.userMapper.getUser";//映射sql的標識字符串
        //執行查詢返回一個惟一user對象的sql
        User user = session.selectOne(statement, 1);*/
        /*String statement = "com.zy.mapping.userMapper.addUser";
        User user = new User();
        user.setName("張三");
        user.setAge(20);
        int user2 = session.insert(statement, user);
        session.commit();
        session.close();
        System.out.println(user2);*/
        //updateUser(session);
        deleteUser(session);
    }
    
    public static void insertUser(SqlSession session){
        String statement = "com.zy.mapping.userMapper.addUser";
        User user = session.selectOne(statement, 1);
        System.out.println(user);
    }
    
    public static void selectUser(SqlSession session){
        String statement = "com.zy.mapping.userMapper.getUser";
        User user = new User();
        user.setId(1);
        int user2 = session.insert(statement, user);
        session.commit();
        session.close();
        System.out.println(user2);
    }
    
    public static void updateUser(SqlSession session){
        String statement = "com.zy.mapping.userMapper.updateUser";
        User user = new User();
        user.setId(6);
        user.setName("李四");
        user.setAge(20);
        int user2 = session.update(statement, user);
        session.commit();
        session.close();
        System.out.println(user2);
    }
    
    public static void deleteUser(SqlSession session){
        String statement = "com.zy.mapping.userMapper.deleteUser";
        User user = new User();
        user.setId(6);
        int user2 = session.delete(statement, user);
        session.commit();
        session.close();
        System.out.println(user2);
    }
}