MyBatis 入门

MyBatis 笔记

项目地址：https://github.com/code-flying/mybatis

一、mybatis 入门

1. 引入jar包

<dependencies>
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.1</version>
        </dependency>

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.21</version>
        </dependency>
</dependencies>

2. 配置数据库信息

db.properties

jdbc.driver=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://192.168.0.102:3306/gp-mybatis?useUnicode=true&characterEncoding=utf-8&rewriteBatchedStatements=true
jdbc.username=root
jdbc.password=****

3. 配置全局mybatis文件

<?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>

    <!-- 引入外部文件 -->
    <properties resource="db.properties" />

    <settings>
        <!-- 开启日志 -->
        <setting name="logImpl" value="STDOUT_LOGGING" />
    </settings>
    
    <typeAliases>
        <!-- 别名 -->
        <typeAlias alias="blog" type="com.mybatis.learn.domain.Blog" />
    </typeAliases>

    <!-- 配置数据库环境 -->
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC" />
            <dataSource type="POOLED">
                <property name="driver" value="${jdbc.driver}" />
                <property name="url" value="${jdbc.url}" />
                <property name="username" value="${jdbc.username}" />
                <property name="password" value="${jdbc.password}" />
            </dataSource>
        </environment>
    </environments>

    <!-- 配置映射器 -->
    <mappers>
        <mapper resource="BlogMapper.xml" />
    </mappers>

</configuration>

4.数据库脚本

CREATE TABLE `blog` (
  `bid` int(11) NOT NULL AUTO_INCREMENT,
  `name` varchar(255) DEFAULT NULL,
  `author_id` int(11) DEFAULT NULL,
  PRIMARY KEY (`bid`)
) ENGINE=InnoDB AUTO_INCREMENT=2 DEFAULT CHARSET=utf8;

CREATE TABLE `author` (
  `author_id` int(16) NOT NULL AUTO_INCREMENT,
  `author_name` varchar(255) DEFAULT NULL,
  PRIMARY KEY (`author_id`)
) ENGINE=InnoDB AUTO_INCREMENT=1002 DEFAULT CHARSET=utf8;

CREATE TABLE `comment` (
  `comment_id` int(16) NOT NULL AUTO_INCREMENT,
  `content` varchar(255) DEFAULT NULL,
  `bid` int(16) DEFAULT NULL,
  PRIMARY KEY (`comment_id`)
) ENGINE=InnoDB AUTO_INCREMENT=3 DEFAULT CHARSET=utf8;

INSERT INTO `blog` (`bid`, `name`, `author_id`) VALUES (1, 'RabbitMQ延时消息', 1001);
INSERT INTO `blog` (`bid`, `name`, `author_id`) VALUES (2, 'MyBatis源码分析', 1008);
INSERT INTO `author` (`author_id`, `author_name`) VALUES (1001, '青山');
INSERT INTO `comment` (`comment_id`, `content`, `bid`) VALUES (1, '写得真好，学习了', 1);
INSERT INTO `comment` (`comment_id`, `content`, `bid`) VALUES (2, '刚好碰到这个问题，谢谢', 1);

5. 编写domain类

/**
 * @author dingding
 *
 */
public class Blog {

    private Integer bid;// 文章ID
    private String name; // 文章标题
    private Integer authorId; // 文章作者ID

    public Integer getBid() {
        return bid;
    }

    public void setBid(Integer bid) {
        this.bid = bid;
    }

    public String getName() {
        return name;
    }

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

    public Integer getAuthorId() {
        return authorId;
    }

    public void setAuthorId(Integer authorId) {
        this.authorId = authorId;
    }

    @Override
    public String toString() {
        return "Blog [bid=" + bid + ", name=" + name + ", authorId=" + authorId
                + "]";
    }

}

6. 编写 mapper

6.1 mapper接口

/**
 * @author dingding
 *
 */
public interface BlogMapper {
    
    /**
     * 根据主键查询文章
     * @param bid
     * @return
     */
    public Blog selectBlogById(Integer bid);

}

6.2 mapper接口对应的xml文件

<?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.learn.mapper.BlogMapper">

    <resultMap type="blog" id="BaseResultMap">
        <id column="bid" property="bid" jdbcType="INTEGER" />
        <result column="name" property="name" jdbcType="VARCHAR" />
        <result column="author_id" property="authorId" jdbcType="INTEGER" />
    </resultMap>

    <select id="selectBlogById" resultMap="BaseResultMap" >
        select * from blog where bid = #{bid}
    </select>

</mapper>

7. 测试

import java.io.IOException;
import java.io.InputStream;

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 org.junit.Test;

import com.mybatis.learn.domain.Blog;
import com.mybatis.learn.mapper.BlogMapper;

/**
 * @author dingding
 *
 */
public class MyBatisTest {
    
    /**
     * 使用MyBatis API方式
     * ibatis 原生方式
     * @throws IOException
     */
    @Test
    public void testStatement() throws IOException{
        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        SqlSession session = sqlSessionFactory.openSession();
        try {
            Blog blog = session.selectOne("com.mybatis.learn.mapper.BlogMapper.selectBlogById", 1);
            System.out.println(blog);
        } catch (Exception e) {
            e.printStackTrace();
        }finally{
            if(session != null){
                session.close();
            }
        }
    }
    
    /**
     * 通过 SqlSession.getMapper(XXXMapper.class)  接口方式
     * @throws IOException
     */
    @Test
    public void testSelect() throws IOException{
        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        SqlSession sqlSession = sqlSessionFactory.openSession();
        
        BlogMapper blogMapper = sqlSession.getMapper(BlogMapper.class);
        Blog blog = blogMapper.selectBlogById(1);
        System.out.println(blog);
        
        if(sqlSession != null){
            sqlSession.close();
        }
        
    }

}

​

来源：https://www.cnblogs.com/lfdingye/p/11638490.html