02-MyBatis-环境搭建

MyBatis 源码

MyBatis官方文档
源码下载地址（推荐使用码云中转下载）
mybatis-parent项目下载地址

1. 选择自己所需要的MyBatis版本下载

2. 查看pom文件中所对应的mybatis-parent项目版本

3. 根据tag下载所需要的项目包。
4. 导入idea，选择jdk进行编译。
5. 新建一个maven模块

pom文件引入依赖

<dependencies>
 <!-- mybatis核心包 -->
    <dependency>
        <groupId>org.mybatis</groupId>
        <artifactId>mybatis</artifactId>
        <version>3.5.1</version>
    </dependency>
            <!-- jdbc的包 -->
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>5.1.32</version>
    </dependency>
            <!-- 查看日志文件的log4j包 -->
    <dependency>
        <groupId>log4j</groupId>
        <artifactId>log4j</artifactId>
        <version>1.2.12</version>
    </dependency>
            <!-- 测试用的依赖包 -->
    <dependency>
        <groupId>junit</groupId>
        <artifactId>junit</artifactId>
        <version>4.11</version>
    </dependency>
            <dependency>
        <groupId>org.javassist</groupId>
        <artifactId>javassist</artifactId>
        <version>3.21.0-GA</version>
    </dependency>
    <dependency>
        <groupId>ognl</groupId>
        <artifactId>ognl</artifactId>
        <version>2.7.3</version>
    </dependency>
    <dependency>
        <groupId>junit</groupId>
        <artifactId>junit</artifactId>
        <version>4.12</version>
        <scope>compile</scope>
</dependency>

6. 项目结构

package com.mybatis.pojo;

/**
 * @author qcc
 * @Package com.mybatis.pojo
 * @Description: TODO
 * @date
 */
public class User {
    private Integer id;

    private String username;

    private String password;

    private String context;

    public Integer getId() {
        return id;
    }

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

    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;
    }

    public String getContext() {
        return context;
    }

    public void setContext(String context) {
        this.context = context;
    }

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", username='" + username + '\'' +
                ", password='" + password + '\'' +
                ", context='" + context + '\'' +
                '}';
    }
}

package com.mybatis.utils;

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

import java.io.IOException;
import java.io.Reader;

/**
 * @author qcc
 * @Package com.mybatis.utils
 * @Description: TODO
 * @date
 */
public class MybatisUtil {
    private static ThreadLocal<SqlSession> threadLocal = new ThreadLocal<SqlSession>();
    private static SqlSessionFactory sqlSessionFactory;

    static {
        try {
            // 读取mybatis核心配置文件
            Reader reader = Resources.getResourceAsReader("mybatis-config.xml");
            // 创建会话工厂
            sqlSessionFactory = new SqlSessionFactoryBuilder().build(reader);
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }

    public static SqlSession getSession() {
        // 获取会话
        SqlSession sqlSession = threadLocal.get();
        if (sqlSession == null) {
            // 从会话工厂获取session
            sqlSession = sqlSessionFactory.openSession();
            // 绑定会话工厂
            threadLocal.set(sqlSession);
        }
        return sqlSession;
    }

    public static void close() {
        SqlSession sqlSession = threadLocal.get();
        if (sqlSession != null) {
            sqlSession.close();
        }
    }
}

<?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" >
<!-- namespace命名必须是唯一的,前期可以直接以所映射的pojo类的唯一路径来命名 -->
<mapper namespace="com.mybatis.pojo.User">
    <!--
        mybaits通过自己手动写sql语句来对数据库进行操作,select就是查询操作
        同样有update,delete,insert
        id:标识符,测试时调用的标识符来调用sql语句,相当于方法名
        resultType:返回值类型
        parameterType:传入的参数类型
        如果是引用数据类型的话,需要传入完整的路径.如:java.lang.String以及对象com.mybatis.pojo.User
        在下方的条件需要以#{}来占位,如果传入类型是对象型,需要与对象的属性名一致
     -->
    <select id="findStudentById" resultType="com.mybatis.pojo.User" parameterType="int">
        select * from user where id=#{id}
    </select>
    <select id="findAll" resultType="com.mybatis.pojo.User">
        select * from user
    </select>
</mapper>

<?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>
    <properties resource="db.properties"></properties>
    <!-- 接收数据库的数据源(元数据) default默认读取以下的配置 -->
    <environments default="mysql">
        <!-- 针对不同的数据库来配置元数据 id:区分元数据 -->
        <!-- 配置MySQL -->
        <environment id="mysql">
            <!-- 事务的管理交给jdbc管理 -->
            <transactionManager type="jdbc"/>
            <!-- 使用properties加载properties中的属性 -->
            <dataSource type="pooled">
                <property name="driver" value="${driver}"/>
                <property name="url" value="${url}"/>
                <property name="username" value="${username}"/>
                <property name="password" value="${password}"/>
            </dataSource>
        </environment>

        <!-- 配置Oracle -->
<!--        <environment id="oracle">-->
<!--            &lt;!&ndash; 事务的管理交给odbc管理 &ndash;&gt;-->
<!--            <transactionManager type="jdbc"/>-->
<!--            <dataSource type="pooled">-->
<!--                <property name="driver" value="com.mysql.jdbc.Driver"/>-->
<!--                <property name="url" value="jdbc:oracle:thin:@localhost:1521/test"/>-->
<!--                <property name="username" value="scott"/>-->
<!--                <property name="password" value="123456"/>-->
<!--            </dataSource>-->
<!--        </environment>-->
    </environments>
    <mappers>
        <mapper resource="mapper/userMapper.xml"/>
    </mappers>
</configuration>

driver=com.mysql.jdbc.Driver
url=jdbc:mysql://localhost:3306/a_test
username=root
password=root

/*
 Navicat Premium Data Transfer

 Source Server         : localhost
 Source Server Type    : MySQL
 Source Server Version : 50729
 Source Host           : localhost:3306
 Source Schema         : a_test

 Target Server Type    : MySQL
 Target Server Version : 50729
 File Encoding         : 65001

 Date: 18/05/2020 23:16:53
*/

SET NAMES utf8mb4;
SET FOREIGN_KEY_CHECKS = 0;

-- ----------------------------
-- Table structure for user
-- ----------------------------
DROP TABLE IF EXISTS `user`;
CREATE TABLE `user` (
  `id` bigint(32) NOT NULL,
  `username` varchar(255) DEFAULT NULL,
  `password` varchar(32) DEFAULT NULL,
  `context` varchar(1000) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

SET FOREIGN_KEY_CHECKS = 1;

package com.mybatis.test;

import com.mybatis.pojo.User;
import com.mybatis.utils.MybatisUtil;
import org.apache.ibatis.session.SqlSession;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;

import java.util.List;

/**
 * @author qcc
 * @Package com.mybatis.test
 * @Description: TODO
 * @date
 */
public class TestMybatis01 {
    private SqlSession session = null;

    @Before
    public void before() {
        //获取会话
        session = MybatisUtil.getSession();
    }

    @Test
    public void select() {
        /**
         * 从会话中调用映射文件中的sql语句,为了防止不同的映射文件标识符重复,通过namespace.标识符来调用
         * 如果后面有参数的话,在后面添加参数
         */
        User user = session.selectOne("com.mybatis.pojo.User.findStudentById",1);
        System.out.println(user);
        List<User> studentList = session.selectList("com.mybatis.pojo.User.findAll");
        for (User student2 : studentList) {
            System.out.println(student2);
        }
    }

    @After
    public void after() {
        session.commit();
        MybatisUtil.close();
    }
}

1. 运行TestMybatis01中的select(),结果如图所示

至此，mybatis源码阅读项目建立成功。