[Java知识库]关于Mybatis中的逆向工程

关于mybatisConfig.xml 配置文件：

在Maven中的Pom中加入插件

<plugin>
    <groupId>org.mybatis.generator</groupId>
    <artifactId>mybatis-generator-maven-plugin</artifactId>
    <version>1.3.2</version>
</plugin>

<?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">
<generatorConfiguration>

    <classPathEntry
            location="D:\apache-maven-3.8.1\repository\mysql\mysql-connector-java\5.1.47\mysql-connector-java-5.1.47.jar"/>

    <context id="DB2Tables"  targetRuntime="MyBatis3">

        <property name="autoDelimitKeywords" value="false"/>

        <property name="javaFileEncoding" value="UTF-8"/>

        <property name="javaFormatt"  />
        <property name="xmlFormatter" value="org.mybatis.generator.api.dom.DefaultXmlFormatter"/>





        <property name="beginningDelimiter" value="`"/>
        <property name="endingDelimiter" value="`"/>



        <commentGenerator>
            <property name="suppressDate" value="true"/>

            <property name="suppressAllComments" value="true"/>
        </commentGenerator>

        <jdbcConnection
                driverClass="com.mysql.jdbc.Driver"
                connectionURL="jdbc:mysql://localhost:3306/hunau?useSSL=false&amp;allowPublicKeyRetrieval=true&amp;serverTimezone=UTC&amp;allowMultiQueries=true&amp;nullCatalogMeansCurrent=true"
                userId="root" password="root">
        </jdbcConnection>
        <javaTypeResolver>
       

            <property name="forceBigDecimals" value="false"/>
        </javaTypeResolver>

        <javaModelGenerator targetPackage="com.bean" targetProject="src/main/java" >

            <property name="constructorBased" value="true"/>

            <property name="enableSubPackages" value="false"/>

            <property name="trimStrings" value="true"/>
        </javaModelGenerator>



        <sqlMapGenerator targetPackage="com.mapper" targetProject="src/main/resources">

            <property name="enableSubPackages" value="false"/>
        </sqlMapGenerator>



        <javaClientGenerator  type="XMLMAPPER" targetPackage="com.mapper" targetProject="src/main/java">
            <property name="enableSubPackages" value="false"/>


        </javaClientGenerator>



        <table tableName="emp" domainObjectName="EmpBean"
               enableInsert="false"
               enableSelectByPrimaryKey="false"         ></table>

        <table tableName="dept" domainObjectName="DeptBean"
               enableInsert="false"
               enableSelectByPrimaryKey="false"         ></table>
    </context>
</generatorConfiguration>

dtd约束 会爆红但是还能运行

ClassPathEntry中的location它代表着数据库驱动jar包位置，

targeRuntime中的值可以为Mybatis3和Mybatis3Simple 前者可以生成带条件的增删改查，

后者相对简单，只能生成基本的增删改查。

后面的property可以不用修改，

<javaModelGenerator targetPackage="com.bean" targetProject="src/main/java" >

<sqlMapGenerator targetPackage="com.mapper" targetProject="src/main/resources">

上面的代码表示自动生成的结果会在某某包下。

<table tableName="emp" domainObjectName="EmpBean">

上面代码表示从数据库中取得emp表,然后在bean目录下生成名字为EmpBean的实体类

最后就是Maven运行配置文件的一行代码:

mybatis-generator:generate -e

运行错误或者多运行了多次,必须把自动生成的文件删除再继续运行,

以下为targeRuntime中的值为Mybatis3运行的结果

各种带条件的查询方法:

import com.bean.EmpBean;
import com.bean.EmpBeanExample;
import com.mapper.EmpBeanMapper;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.*;
import org.junit.Test;


import java.io.IOException;
import java.io.InputStream;
import java.math.BigDecimal;
import java.util.List;

public class Test001 {
    @Test
    public void testMybatis() throws IOException {
        InputStream in = Resources.getResourceAsStream("mybatis-config.xml");
        SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(in);
        SqlSession session =sessionFactory.openSession();
        EmpBeanMapper mapper = session.getMapper(EmpBeanMapper.class);

        EmpBeanExample empBeanExample= new EmpBeanExample();
        EmpBeanExample.Criteria criteria = empBeanExample.createCriteria();
           criteria.andDeptnoEqualTo((short)10);
           criteria.andSalGreaterThan(new BigDecimal(1000));
        List<EmpBean> empBeanList =  mapper.selectByExample(empBeanExample);
        for (EmpBean E:empBeanList){
            System.out.println(E);
            //  Row: 7782, CLARK, MANAGER, 7839, 1981-06-09, 2450.00, null, 10
            //  Row: 7839, KING, PRESIDENT, null, 1981-11-17, 5000.00, null, 10
        }
    }
}

带条件的查询必须先new出Example实例,

Example中的createCriteria方法产生criteria内部类对象.