【SSM 4】Mybatis逆向生成工具

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！