【SSM 4】Mybatis逆向生成工具

2022-03-24 06:17:21

在上一篇博客中说到，Mybatis是灵活的SQL语句应用，不想Hibernate一样有其封装好的方法，那么，当我们用Mybatis的时候（Hibernate），我们都需要编写其实体类，和配置文件。本篇博客，就介绍一下Mybatis的逆向生成工具。

一、思路

回想一下，在最早运用EF的时候，我们首先通过可视化界面，连接数据库，然后选择要使用的表单，然后，我们就可以自动生成实体类。在运用Hibernate的时候，我们可以先编写Hibernate的配置文件，连接数据库，然后编写实体类文件，然后通过读取HIbernate的配置文件，正向生成数据库表单。然后我们也可以运用工具，从数据库表，生成HIbernate的实体。那么，到了Mybatis这儿，可以怎么做呢？思路如下：

1，连接数据库，指定表单生成

2，指定代码生成后的存放路径，以及要生成哪些代码

2，读取配置文件，生成代码

二、实现

首先是建立了一个Java project，然后引入了5个jar包，分别是：

log4j-1.2.16.jar；Mybatis-3.2.3.jar；Mybatis-generator-core-1.3.2.jar；mysal-connector-java-5.1.28-bin.jar；ojdbc14.jar

版本可以自行确定！

然后，编写mybatis.xml配置文件，代码内容如下：

<span style="font-family:KaiTi_GB2312;font-size:18px;"><?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>

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

		<commentGenerator>

			<!-- 是否去除自动生成的注释 true：是 ： false:否 -->

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

		</commentGenerator>

		<!--数据库连接的信息：驱动类、连接地址、用户名、密码 -->

		<jdbcConnection driverClass="com.mysql.jdbc.Driver"

			connectionURL="jdbc:mysql://localhost:3306/Test" userId="root"

			password="Angel0626">

		</jdbcConnection>

		<!-- 默认false，把JDBC DECIMAL 和 NUMERIC 类型解析为 Integer，为 true时把JDBC DECIMAL 和

			NUMERIC 类型解析为java.math.BigDecimal -->

		<javaTypeResolver>

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

		</javaTypeResolver>

		<!-- targetProject:生成PO类的位置 -->

		<javaModelGenerator targetPackage="pojo"

			targetProject=".\src">

			<!-- enableSubPackages:是否让schema作为包的后缀 -->

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

			<!-- 从数据库返回的值被清理前后的空格 -->

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

		</javaModelGenerator>

        <!-- targetProject:mapper映射文件生成的位置 -->

		<sqlMapGenerator targetPackage="mapper"

			targetProject=".\src">

			<!-- enableSubPackages:是否让schema作为包的后缀 -->

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

		</sqlMapGenerator>

		<!-- targetPackage：mapper接口生成的位置 -->

		<javaClientGenerator type="XMLMAPPER"

			targetPackage="mapper"

			targetProject=".\src">

			<!-- enableSubPackages:是否让schema作为包的后缀 -->

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

		</javaClientGenerator>

		<!-- 指定数据库表 -->

		<table schema="" tableName="tb_content"></table>

		<table schema="" tableName="tb_content_category"></table>

		<table schema="" tableName="tb_item"></table>

		<table schema="" tableName="tb_item_cat"></table>

		<table schema="" tableName="tb_item_desc"></table>

		<table schema="" tableName="tb_item_param"></table>

		<table schema="" tableName="tb_item_param_item"></table>

		<table schema="" tableName="tb_order"></table>

		<table schema="" tableName="tb_order_item"></table>

		<table schema="" tableName="tb_order_shipping"></table>

		<table schema="" tableName="tb_user"></table>

	</context>

</generatorConfiguration>

</span>

其次，编写实现方法，代码如下：

<span style="font-family:KaiTi_GB2312;font-size:18px;">package test;

import java.io.File;

import java.util.ArrayList;

import java.util.List;

import org.mybatis.generator.api.MyBatisGenerator;

import org.mybatis.generator.config.Configuration;

import org.mybatis.generator.config.xml.ConfigurationParser;

import org.mybatis.generator.internal.DefaultShellCallback;

public class GeneratorSqlmap {

	public void generator() throws Exception{

		List<String> warnings=new ArrayList<String>();

		boolean overwrite=true;

		File configFile=new File("mybatis.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);

	}

	public static void main(String[] args) throws Exception{

		try{

			GeneratorSqlmap generatorSqlmap=new GeneratorSqlmap();

			generatorSqlmap.generator();

		}catch(Exception e){

			e.printStackTrace();

		}

	}

}

</span>

运行其main方法，即可生成相应代码。

代码示例：以TbUser表为例：

实体类：

<span style="font-family:KaiTi_GB2312;font-size:18px;">public class TbUser {

    private Long id;

    private String username;

    private String password;

    private String phone;

    private String email;

    private Date created;

    private Date updated;

    public Long getId() {

        return id;

    }

    public void setId(Long id) {

        this.id = id;

    }</span>

mapper接口：

<span style="font-family:KaiTi_GB2312;font-size:18px;">package mapper;

import java.util.List;

import org.apache.ibatis.annotations.Param;

import pojo.TbUser;

import pojo.TbUserExample;

public interface TbUserMapper {

    int countByExample(TbUserExample example);

    int deleteByExample(TbUserExample example);

    int deleteByPrimaryKey(Long id);

    int insert(TbUser record);

    int insertSelective(TbUser record);

    List<TbUser> selectByExample(TbUserExample example);

    TbUser selectByPrimaryKey(Long id);

    int updateByExampleSelective(@Param("record") TbUser record, @Param("example") TbUserExample example);

    int updateByExample(@Param("record") TbUser record, @Param("example") TbUserExample example);

    int updateByPrimaryKeySelective(TbUser record);

    int updateByPrimaryKey(TbUser record);

}</span>

mapper.xml实现：

<span style="font-family:KaiTi_GB2312;font-size:18px;"><?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="mapper.TbUserMapper" >

  <resultMap id="BaseResultMap" type="pojo.TbUser" >

    <id column="id" property="id" jdbcType="BIGINT" />

    <result column="username" property="username" jdbcType="VARCHAR" />

    <result column="password" property="password" jdbcType="VARCHAR" />

    <result column="phone" property="phone" jdbcType="VARCHAR" />

    <result column="email" property="email" jdbcType="VARCHAR" />

    <result column="created" property="created" jdbcType="TIMESTAMP" />

    <result column="updated" property="updated" jdbcType="TIMESTAMP" />

  </resultMap>

  <sql id="Example_Where_Clause" >

    <where >

      <foreach collection="oredCriteria" item="criteria" separator="or" >

        <if test="criteria.valid" >

          <trim prefix="(" suffix=")" prefixOverrides="and" >

            <foreach collection="criteria.criteria" item="criterion" >

              <choose >

                <when test="criterion.noValue" >

                  and ${criterion.condition}

                </when>

                <when test="criterion.singleValue" >

                  and ${criterion.condition} #{criterion.value}

                </when>

                <when test="criterion.betweenValue" >

                  and ${criterion.condition} #{criterion.value} and #{criterion.secondValue}

                </when>

                <when test="criterion.listValue" >

                  and ${criterion.condition}

                  <foreach collection="criterion.value" item="listItem" open="(" close=")" separator="," >

                    #{listItem}

                  </foreach>

                </when>

              </choose>

            </foreach>

          </trim>

        </if>

      </foreach>

    </where>

  </sql>

  <sql id="Update_By_Example_Where_Clause" >

    <where >

      <foreach collection="example.oredCriteria" item="criteria" separator="or" >

        <if test="criteria.valid" >

          <trim prefix="(" suffix=")" prefixOverrides="and" >

            <foreach collection="criteria.criteria" item="criterion" >

              <choose >

                <when test="criterion.noValue" >

                  and ${criterion.condition}

                </when>

                <when test="criterion.singleValue" >

                  and ${criterion.condition} #{criterion.value}

                </when>

                <when test="criterion.betweenValue" >

                  and ${criterion.condition} #{criterion.value} and #{criterion.secondValue}

                </when>

                <when test="criterion.listValue" >

                  and ${criterion.condition}

                  <foreach collection="criterion.value" item="listItem" open="(" close=")" separator="," >

                    #{listItem}

                  </foreach>

                </when>

              </choose>

            </foreach>

          </trim>

        </if>

      </foreach>

    </where>

  </sql>

  <sql id="Base_Column_List" >

    id, username, password, phone, email, created, updated

  </sql>

  <select id="selectByExample" resultMap="BaseResultMap" parameterType="pojo.TbUserExample" >

    select

    <if test="distinct" >

      distinct

    </if>

    <include refid="Base_Column_List" />

    from tb_user

    <if test="_parameter != null" >

      <include refid="Example_Where_Clause" />

    </if>

    <if test="orderByClause != null" >

      order by ${orderByClause}

    </if>

  </select>

  <select id="selectByPrimaryKey" resultMap="BaseResultMap" parameterType="java.lang.Long" >

    select

    <include refid="Base_Column_List" />

    from tb_user

    where id = #{id,jdbcType=BIGINT}

  </select>

  <delete id="deleteByPrimaryKey" parameterType="java.lang.Long" >

    delete from tb_user

    where id = #{id,jdbcType=BIGINT}

  </delete>

  <delete id="deleteByExample" parameterType="pojo.TbUserExample" >

    delete from tb_user

    <if test="_parameter != null" >

      <include refid="Example_Where_Clause" />

    </if>

  </delete>

  <insert id="insert" parameterType="pojo.TbUser" >

    insert into tb_user (id, username, password,

      phone, email, created,

      updated)

    values (#{id,jdbcType=BIGINT}, #{username,jdbcType=VARCHAR}, #{password,jdbcType=VARCHAR},

      #{phone,jdbcType=VARCHAR}, #{email,jdbcType=VARCHAR}, #{created,jdbcType=TIMESTAMP},

      #{updated,jdbcType=TIMESTAMP})

  </insert>

  <insert id="insertSelective" parameterType="pojo.TbUser" >

    insert into tb_user

    <trim prefix="(" suffix=")" suffixOverrides="," >

      <if test="id != null" >

        id,

      </if>

      <if test="username != null" >

        username,

      </if>

      <if test="password != null" >

        password,

      </if>

      <if test="phone != null" >

        phone,

      </if>

      <if test="email != null" >

        email,

      </if>

      <if test="created != null" >

        created,

      </if>

      <if test="updated != null" >

        updated,

      </if>

    </trim>

    <trim prefix="values (" suffix=")" suffixOverrides="," >

      <if test="id != null" >

        #{id,jdbcType=BIGINT},

      </if>

      <if test="username != null" >

        #{username,jdbcType=VARCHAR},

      </if>

      <if test="password != null" >

        #{password,jdbcType=VARCHAR},

      </if>

      <if test="phone != null" >

        #{phone,jdbcType=VARCHAR},

      </if>

      <if test="email != null" >

        #{email,jdbcType=VARCHAR},

      </if>

      <if test="created != null" >

        #{created,jdbcType=TIMESTAMP},

      </if>

      <if test="updated != null" >

        #{updated,jdbcType=TIMESTAMP},

      </if>

    </trim>

  </insert>

  <select id="countByExample" parameterType="pojo.TbUserExample" resultType="java.lang.Integer" >

    select count(*) from tb_user

    <if test="_parameter != null" >

      <include refid="Example_Where_Clause" />

    </if>

  </select>

  <update id="updateByExampleSelective" parameterType="map" >

    update tb_user

    <set >

      <if test="record.id != null" >

        id = #{record.id,jdbcType=BIGINT},

      </if>

      <if test="record.username != null" >

        username = #{record.username,jdbcType=VARCHAR},

      </if>

      <if test="record.password != null" >

        password = #{record.password,jdbcType=VARCHAR},

      </if>

      <if test="record.phone != null" >

        phone = #{record.phone,jdbcType=VARCHAR},

      </if>

      <if test="record.email != null" >

        email = #{record.email,jdbcType=VARCHAR},

      </if>

      <if test="record.created != null" >

        created = #{record.created,jdbcType=TIMESTAMP},

      </if>

      <if test="record.updated != null" >

        updated = #{record.updated,jdbcType=TIMESTAMP},

      </if>

    </set>

    <if test="_parameter != null" >

      <include refid="Update_By_Example_Where_Clause" />

    </if>

  </update>

  <update id="updateByExample" parameterType="map" >

    update tb_user

    set id = #{record.id,jdbcType=BIGINT},

      username = #{record.username,jdbcType=VARCHAR},

      password = #{record.password,jdbcType=VARCHAR},

      phone = #{record.phone,jdbcType=VARCHAR},

      email = #{record.email,jdbcType=VARCHAR},

      created = #{record.created,jdbcType=TIMESTAMP},

      updated = #{record.updated,jdbcType=TIMESTAMP}

    <if test="_parameter != null" >

      <include refid="Update_By_Example_Where_Clause" />

    </if>

  </update>

  <update id="updateByPrimaryKeySelective" parameterType="pojo.TbUser" >

    update tb_user

    <set >

      <if test="username != null" >

        username = #{username,jdbcType=VARCHAR},

      </if>

      <if test="password != null" >

        password = #{password,jdbcType=VARCHAR},

      </if>

      <if test="phone != null" >

        phone = #{phone,jdbcType=VARCHAR},

      </if>

      <if test="email != null" >

        email = #{email,jdbcType=VARCHAR},

      </if>

      <if test="created != null" >

        created = #{created,jdbcType=TIMESTAMP},

      </if>

      <if test="updated != null" >

        updated = #{updated,jdbcType=TIMESTAMP},

      </if>

    </set>

    where id = #{id,jdbcType=BIGINT}

  </update>

  <update id="updateByPrimaryKey" parameterType="pojo.TbUser" >

    update tb_user

    set username = #{username,jdbcType=VARCHAR},

      password = #{password,jdbcType=VARCHAR},

      phone = #{phone,jdbcType=VARCHAR},

      email = #{email,jdbcType=VARCHAR},

      created = #{created,jdbcType=TIMESTAMP},

      updated = #{updated,jdbcType=TIMESTAMP}

    where id = #{id,jdbcType=BIGINT}

  </update>

</mapper></span>

三、总结

从生成的代码可以看出，生成的代码，基本上解决了对于一个实体操作的增删改查，但是，每个实体的代码都是这样的丰富，还能不能继续往上抽象一层呢？下一篇博客介绍Mybatis的底层封装思路！

码农公寓

一、思路

二、实现

三、总结

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