Mybatis generator – 小飞侠

Mybatis generator

Post author:xfxia
Post published:2023年12月25日
Post category:其他

步骤1.在pom.xml文件中添加MBG插件

            <plugin>
                <groupId>org.mybatis.generator</groupId>
                <artifactId>mybatis-generator-maven-plugin</artifactId>
                <version>1.4.0</version>
                <configuration>
<!--                    这里要修改相应的路径-->
                    <configurationFile>${basedir}/src/main/resources/mybatis/generator/generatorConfig.xml</configurationFile>
                    <overwrite>true</overwrite>
                </configuration>
                <dependencies>
                    <dependency>
                        <groupId>mysql</groupId>
                        <artifactId>mysql-connector-java</artifactId>
                        <version>${mysqlversion}</version>
                    </dependency>
                </dependencies>
            </plugin>

步骤2：编写generatorConfig.xml文件，在上一步路径下新建该文件

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE generatorConfiguration
        PUBLIC "-//mybatis.org//DTD MyBatis Generator Configuration 1.0//EN"
        "http://mybatis.org/dtd/mybatis-generator-config_1_0.dtd">
<!--        要是爆红，就是idea没下载dtd，只需下载即可-->
<generatorConfiguration>
    <context id="MYSQLTables" targetRuntime="MyBatis3">
<!--        关闭注释的生成-->
        <commentGenerator>
            <property name="suppressAllComments" value="true"></property>
        </commentGenerator>

<!--        虽然插件中配置了<overwrite>true</overwrite>，但是只对java文件有效，对mapper文件无效，使用UnnergeableXmlMappersPlugin才可以覆盖xml文件-->
<!--        <plugin type="org.mybatis.generator.plugins.UnnergeableXmlMappersPlugin"></plugin>-->
<!--        设置数据库连接，需要修改-->
        <jdbcConnection driverClass="com.mysql.jdbc.Driver"
                        connectionURL="jdbc:mysql://127.0.0.1:3306/mybatisdemo"
                        userId="root"
                        password="123456">
        </jdbcConnection>

        <javaTypeResolver >
            <property name="forceBigDecimals" value="false" />
        </javaTypeResolver>
<!--        实体类-->
        <javaModelGenerator targetPackage="com.sqm.domain" targetProject="src/main/java">
            <property name="enableSubPackages" value="true" />
            <property name="trimStrings" value="true" />
        </javaModelGenerator>
<!--        mapper映射文件-->
        <sqlMapGenerator targetPackage="mybatis.mapper"  targetProject="src/main/resources">
            <property name="enableSubPackages" value="true" />
        </sqlMapGenerator>
<!--        mapper到接口-->
        <javaClientGenerator type="XMLMAPPER" targetPackage="com.sqm.mapper"  targetProject="src/main/java">
            <property name="enableSubPackages" value="true" />
        </javaClientGenerator>

<!--        选择数据表（data），设置实体类名为knowledge-->
        <table tableName="data" domainObjectName="knowledge"></table>
<!--        <table schema="DB2ADMIN" tableName="ALLTYPES" domainObjectName="Customer" >-->
<!--            <property name="useActualColumnNames" value="true"/>-->
<!--            <generatedKey column="ID" sqlStatement="DB2" identity="true" />-->
<!--            <columnOverride column="DATE_FIELD" property="startDate" />-->
<!--            <ignoreColumn column="FRED" />-->
<!--            <columnOverride column="LONG_VARCHAR_FIELD" jdbcType="VARCHAR" />-->
<!--        </table>-->

    </context>
</generatorConfiguration>

步骤3：在maven中运行相应的插件

点击mybatis-generator:generate 右键运行Maven构建

最后结果

自动生成成功

如何利用生成的代码？

MGB会帮我们自动生成许多方法

package com.sqm.mapper;

import com.sqm.domain.knowledge;
import com.sqm.domain.knowledgeExample;
import java.util.List;
import org.apache.ibatis.annotations.Param;

public interface knowledgeMapper {

    //求和
    long countByExample(knowledgeExample example);

    //删除
    int deleteByExample(knowledgeExample example);

    //通过主键删除
    int deleteByPrimaryKey(String name);

    //普通插入 一般都用这个！！，区别就是，要是插入值中有些是空，普通插入就是空，而智能插入则不插入
    // insert into data(name, symbolsize, category, des) values(1,2,null, null) 普通插入
    // insert into data(name, symbolsize) values(1,2) 智能插入
    int insert(knowledge record);

    //智能插入
    int insertSelective(knowledge record);

    //传入空对象或者null则返回全部 并且可以设置条件查询
    List<knowledge> selectByExample(knowledgeExample example);

    //通过主键查询
    knowledge selectByPrimaryKey(String name);

    //选择性更新，用这个
//    第一个参数，改变后的值 第二个参数查找的条件
    int updateByExampleSelective(@Param("record") knowledge record, @Param("example") knowledgeExample example);

    int updateByExample(@Param("record") knowledge record, @Param("example") knowledgeExample example);

    //更新一定要用这个
    int updateByPrimaryKeySelective(knowledge record);

    //不要用这个
    int updateByPrimaryKey(knowledge record);
}

如何利用如下所示

我们新建一个test类来进行演示

import com.sqm.domain.knowledge;
import com.sqm.domain.knowledgeExample;
import com.sqm.mapper.UserMapper;
import com.sqm.mapper.knowledgeMapper;
import org.apache.ibatis.annotations.Param;
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.After;
import org.junit.Before;
import org.junit.Test;

import java.io.IOException;
import java.io.InputStream;
import java.lang.reflect.Array;
import java.sql.SQLException;
import java.util.*;

public class KnowledgeDaoTest {
    knowledgeMapper mapper;
    SqlSession sqlSession;
    @Before
    public void before(){
        try {
            InputStream inputStream = Resources.getResourceAsStream("mybatis/mybatis-config.xml");
            SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
            sqlSession = sqlSessionFactory.openSession();
            sqlSession.getConnection().setAutoCommit(true);
            mapper = sqlSession.getMapper(knowledgeMapper.class);
            sqlSession.getConnection().setAutoCommit(true);
            inputStream.close();
        } catch (IOException e) {
            throw new RuntimeException(e);
        } catch (SQLException e) {
            throw new RuntimeException(e);
        }
    }

    @After
    public  void after(){
        sqlSession.close();
    }

    @Test
    public void countByExample(){
        knowledgeExample knowledgeExample = new knowledgeExample();
        knowledgeExample.createCriteria().andCategoryEqualTo("维吾尔族");
        long total = mapper.countByExample(knowledgeExample);//输出所有数据条数
        System.out.println(total);
    }

    @Test
    public void deleteByExample(){
        knowledgeExample knowledgeExample = new knowledgeExample();
        knowledgeExample.createCriteria().andCategoryIn(Arrays.asList(new String[]{"维吾尔族"}));
        mapper.deleteByExample(knowledgeExample);
    }

    @Test
    public void deleteByPrimaryKey(){
        mapper.deleteByPrimaryKey("发展历史");
    }

    @Test//普通插入
    public void insert(){
        knowledge knowledge = new knowledge();
        knowledge.setName("史启明");
        knowledge.setCategory("汉族");
        mapper.insert(knowledge);
    }

    @Test
    public void insertSelective(){
        knowledge knowledge = new knowledge();
        knowledge.setName("史启2");
        knowledge.setCategory("汉族");
        mapper.insertSelective(knowledge);
    }

    @Test//传入空对象或者null则返回全部 并且可以设置条件查询
    public void selectByExample(){
        knowledgeExample example = new knowledgeExample();
//        knowledgeExample.Criteria criteria = example.createCriteria();
//        criteria.andCategoryEqualTo("语言");//设置条件查找
        example.createCriteria().andCategoryIn(Arrays.asList(new String[]{"语言", "维吾尔族"})).andSymbolsizeLessThan(70);//where in 还可以串联
//        example.createCriteria().andCategoryEqualTo("科学");//要是连着写两行，会自动用or串接起来，要是写成1行则会用and串接

        List<knowledge> knowledgeList = mapper.selectByExample(example);

        for (knowledge knowledge : knowledgeList) {
            System.out.println(knowledge.toString());
        }
    }


    @Test//通过主键查询
    public void selectByPrimaryKey(){
        knowledge kno = mapper.selectByPrimaryKey("中心");
        System.out.println(kno.toString());
    }

    @Test//选择性更新，用这个
    public void updateByExampleSelective(){
        //更改
        knowledge knowledge = new knowledge();
        knowledge.setDes("我最爱的吃的");

        //查找的条件
        knowledgeExample knowledgeExample = new knowledgeExample();
        knowledgeExample.createCriteria().andCategoryEqualTo("饮食");

        mapper.updateByExampleSelective(knowledge, knowledgeExample);

    }

    @Test//这个别用
    public void updateByExample(){}

    @Test//更新操作一定要用这个
    public void updateByPrimaryKeySelective(){
        knowledge knowledge = new knowledge();
        knowledge.setName("《乌古斯可汗传》");
        knowledge.setSymbolsize(200);
        mapper.updateByPrimaryKeySelective(knowledge);
    }

    @Test//更新操作不要用这个
    public void updateByPrimaryKey(){
        knowledge knowledge = new knowledge();
        knowledge.setName("《乌古斯可汗传》");
        knowledge.setSymbolsize(200);
        mapper.updateByPrimaryKey(knowledge);
    }


}

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原文链接：https://blog.csdn.net/falldeep/article/details/130147807