【SSM框架】MyBatis的逆向工程

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目录

创建逆向工程的步骤

①创建表

②添加依赖和插件

③创建MyBatis的核心配置文件

④创建逆向工程的配置文件

⑤创建log4j.xml配置文件

⑥执行MBG插件的generate目标

 ⑦添加 SqlSessionUtils 工具类

⑧测试功能

---

• 先创建Java实体类，由框架负责根据实体类生成数据库表。 Hibernate是支持正向工程的。

• Java实体类
• Mapper接口
• Mapper映射文件

创建逆向工程的步骤

①创建表

在ssm数据库下 创建2张表（t_emp   t_dept）

 t_emp  设置如下字段，并添加一部分数据

t_dept  设置如下字段，并添加一部分数据

②添加依赖和插件

• 新建一个项目

 

 

 下面代码复制到pom.xml中

"1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0modelVersion>
 
    <groupId>org.examplegroupId>
    <artifactId>mybatis_bmgartifactId>
    <version>1.0-SNAPSHOTversion>
 
 
    <dependencies>
        <dependency>
            <groupId>org.mybatisgroupId>
            <artifactId>mybatisartifactId>
            <version>3.5.7version>
        dependency>
        
        <dependency>
            <groupId>junitgroupId>
            <artifactId>junitartifactId>
            <version>4.12version>
            <scope>testscope>
        dependency>
        
        <dependency>
            <groupId>log4jgroupId>
            <artifactId>log4jartifactId>
            <version>1.2.17version>
        dependency>
        <dependency>
            <groupId>mysqlgroupId>
            <artifactId>mysql-connector-javaartifactId>
            <version>5.1.3version>
        dependency>
        <dependency>
            <groupId>org.junit.jupitergroupId>
            <artifactId>junit-jupiterartifactId>
            <version>RELEASEversion>
            <scope>compilescope>
        dependency>
 
    dependencies>
    
    <build>
    
    <plugins>
        
        <plugin>
            <groupId>org.mybatis.generatorgroupId>
            <artifactId>mybatis-generator-maven-pluginartifactId>
            <version>1.3.0version>
            
            <dependencies>
                
                <dependency>
                    <groupId>org.mybatis.generatorgroupId>
                    <artifactId>mybatis-generator-coreartifactId>
                    <version>1.3.2version>
                dependency>
                
                <dependency>
                    <groupId>mysqlgroupId>
                    <artifactId>mysql-connector-javaartifactId>
                    <version>8.0.16version>
                dependency>
            dependencies>
        plugin>
    plugins>
    build>
 
project>

③创建MyBatis的核心配置文件

这里的数据库账号密码改成自己的：

"1.0" encoding="UTF-8" ?>
configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN" "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
 
    <settings>
        <setting name="mapUnderscoreToCamelCase" value="true"/>
        <setting name="lazyLoadingEnabled" value="true"/>
        <setting name="aggressiveLazyLoading" value="false"/>
    settings>
    <typeAliases>
        
        <package name="com.atguigu.mybatis.pojo"/>
    typeAliases>
 
 
 
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://localhost:3306/ssm? serverTimezone=UTC"/>
                <property name="username" value="root"/>
                <property name="password" value="root"/>
            dataSource>
        environment>
    environments>
 
 
 
 
    
    <mappers>
        
        <package name="com.atguigu.mybatis.mapper"/>
    mappers>
 
configuration>
 
 

④创建逆向工程的配置文件

"1.0" encoding="UTF-8"?>
generatorConfiguration
        PUBLIC "-//mybatis.org//DTD MyBatis Generator Configuration 1.0//EN"
        "http://mybatis.org/dtd/mybatis-generator-config_1_0.dtd">
<generatorConfiguration>
    
    <context id="DB2Tables" targetRuntime="MyBatis3">
        
        <jdbcConnection driverClass="com.mysql.cj.jdbc.Driver"
                        connectionURL="jdbc:mysql://localhost:3306/ssm?
serverTimezone=UTC"
                        userId="root"
                        password="root">
        jdbcConnection>
        
        <javaModelGenerator targetPackage="com.atguigu.mybatis.pojo"
                            targetProject=".\src\main\java">
            <property name="enableSubPackages" value="true" />
            <property name="trimStrings" value="true" />
        javaModelGenerator>
        
        <sqlMapGenerator targetPackage="com.atguigu.mybatis.mapper"
                         targetProject=".\src\main\resources">
            <property name="enableSubPackages" value="true" />
        sqlMapGenerator>
        
        <javaClientGenerator type="XMLMAPPER"
                             targetPackage="com.atguigu.mybatis.mapper" targetProject=".\src\main\java">
            <property name="enableSubPackages" value="true" />
        javaClientGenerator>
        
        
        
        <table tableName="t_emp" domainObjectName="Emp"/>
        <table tableName="t_dept" domainObjectName="Dept"/>
    context>
generatorConfiguration>

⑤创建log4j.xml配置文件

"1.0" encoding="UTF-8"?>
generatorConfiguration
        PUBLIC "-//mybatis.org//DTD MyBatis Generator Configuration 1.0//EN"
        "http://mybatis.org/dtd/mybatis-generator-config_1_0.dtd">
<generatorConfiguration>
    
    <context id="DB2Tables" targetRuntime="MyBatis3">
        
        <jdbcConnection driverClass="com.mysql.cj.jdbc.Driver"
                        connectionURL="jdbc:mysql://localhost:3306/ssm?
serverTimezone=UTC"
                        userId="root"
                        password="root">
        jdbcConnection>
        
        <javaModelGenerator targetPackage="com.atguigu.mybatis.pojo"
                            targetProject=".\src\main\java">
            <property name="enableSubPackages" value="true" />
            <property name="trimStrings" value="true" />
        javaModelGenerator>
        
        <sqlMapGenerator targetPackage="com.atguigu.mybatis.mapper"
                         targetProject=".\src\main\resources">
            <property name="enableSubPackages" value="true" />
        sqlMapGenerator>
        
        <javaClientGenerator type="XMLMAPPER"
                             targetPackage="com.atguigu.mybatis.mapper" targetProject=".\src\main\java">
            <property name="enableSubPackages" value="true" />
        javaClientGenerator>
        
        
        
        <table tableName="t_emp" domainObjectName="Emp"/>
        <table tableName="t_dept" domainObjectName="Dept"/>
    context>
generatorConfiguration>

⑥执行MBG插件的generate目标

未执行前：

点击执行插件

执行后： 

 ⑦添加 SqlSessionUtils 工具类

 

package com.atguigu.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.InputStream;
 
public class SqlSessionUtils {
 
    public SqlSession getSqlSession() {
        SqlSession sqlSession = null;
        {
            try {
                InputStream is = Resources.getResourceAsStream("mybatis-config.xml");
                SqlSessionFactoryBuilder sqlSessionFactoryBuilder = new SqlSessionFactoryBuilder();
                SqlSessionFactory sqlSessionFactory = sqlSessionFactoryBuilder.build(is);
                sqlSession = sqlSessionFactory.openSession(true);
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        return sqlSession;
    }
 
 
}

⑧测试功能

import com.atguigu.mybatis.mapper.EmpMapper;
import com.atguigu.mybatis.pojo.Emp;
import com.atguigu.mybatis.pojo.EmpExample;
import com.atguigu.mybatis.utils.SqlSessionUtils;
import org.apache.ibatis.session.SqlSession;
 
import java.util.List;
 
public class Test {
    @org.junit.Test
    public void  test(){
        SqlSessionUtils sqlSessionUtils1 = new SqlSessionUtils();
        SqlSession sqlSession1 = sqlSessionUtils1.getSqlSession();
        EmpMapper mapper = sqlSession1.getMapper(EmpMapper.class);
 
        EmpExample empExample = new EmpExample();
        empExample.createCriteria().andEmpNameEqualTo("李四");
        List emps = mapper.selectByExample(empExample);
 
        System.out.println(emps);
 
 
    }
 
 
}

 上面图片  查询时 显示的是地址，我们可以加一个toString方法