【编程技巧】mybatis如何快速构建pojo和mapper以及sql映射

一、准备相关依赖

在pom文件中添加generator依赖

        <dependency>
            <groupId>org.mybatis.generator</groupId>
            <artifactId>mybatis-generator-core</artifactId>
            <version>1.4.1</version>
        </dependency>

二、配置xml

在资源目录创建generator.xml文件，设置相关配置

<!DOCTYPE generatorConfiguration PUBLIC
        "-//mybatis.org//DTD MyBatis Generator Configuration 1.0//EN"
        "http://mybatis.org/dtd/mybatis-generator-config_1_0.dtd">
<generatorConfiguration>
    <context id="simple" targetRuntime="MyBatis3">
        <jdbcConnection driverClass="com.mysql.cj.jdbc.Driver"
                        connectionURL="jdbc:mysql:///mydb?serverTimezone=GMT%2B8"
                        userId="root"
                        password="root"/>
        <!--实体类-->
        <javaModelGenerator targetPackage="com.godgy.pojo" targetProject="src/main/java"/>
        <!--mapper映射文件-->
        <sqlMapGenerator targetPackage="com.godgy.mapper" targetProject="src/main/resources"/>
        <!--mapper接口-->
        <javaClientGenerator type="XMLMAPPER" targetPackage="com.godgy.mapper" targetProject="src/main/java"/>
        <!--表名-->
        <table tableName="book" />
    </context>
</generatorConfiguration>

三、创建generator类，并运行

package com.godgy.utils;

/**
 * @author : Mr.Godgy
 * @version : 1.0
 * @date : 2022/8/13
 * @description:
 */

import org.mybatis.generator.api.MyBatisGenerator;
import org.mybatis.generator.config.Configuration;
import org.mybatis.generator.config.xml.ConfigurationParser;
import org.mybatis.generator.exception.InvalidConfigurationException;
import org.mybatis.generator.exception.XMLParserException;
import org.mybatis.generator.internal.DefaultShellCallback;

import java.io.File;
import java.io.IOException;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;

public class GeneratorMain {

    public static void main(String[] args) throws XMLParserException, IOException, InvalidConfigurationException, SQLException, InterruptedException {
        List<String> warnings = new ArrayList<String>();
        boolean overwrite = true;
        //配置文件的位置
        File configFile = new File("E:\\JavaProject\\myssmdemo\\src\\main\\resources\\generator.xml");
        ConfigurationParser cp = new ConfigurationParser(warnings);
        Configuration config = cp.parseConfiguration(configFile);
        DefaultShellCallback callback = new DefaultShellCallback(overwrite);
        MyBatisGenerator myBatisGenerator = new MyBatisGenerator(config, callback, warnings);
        myBatisGenerator.generate(null);
    }

}

这里直接右键运行main方法，即可根据数据库相关表，生成对应的pojo和mapper以及映射文件。

四、测试功能

package com.godgy.test;

import com.godgy.mapper.BookMapper;
import com.godgy.pojo.Book;
import com.godgy.pojo.BookExample;
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 java.io.IOException;
import java.io.InputStream;
import java.util.List;


/**
 * @author : Mr.Godgy
 * @version : 1.0
 * @date : 2022/8/13
 * @description:
 */
public class MybatisTest {
    @Test
    public void testFindAll() throws IOException {
        //配置资源位置
        InputStream resourceAsStream = Resources.getResourceAsStream("MybatisConfig.xml");
        //创建会话工厂
        SqlSessionFactory ssf = new SqlSessionFactoryBuilder().build(resourceAsStream);
        //创建一个会话
        SqlSession sqlSession = ssf.openSession(true);
        //通过反射获取对象方法
        BookMapper bookMapper = sqlSession.getMapper(BookMapper.class);
        //执行查询方法
        BookExample bookExample = new BookExample();
        List<Book> books = bookMapper.selectByExample(bookExample);
        System.out.println(books);
        //关闭会话(不要忘了)
        sqlSession.close();
    }
}

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