MyBatis學習筆記（逆向工程）

一、什麼是逆向工程

  MyBatis的一個主要的特點就是需要程序員自己編寫sql，那麼如果表太多的話，難免會很麻煩，所以mybatis官方提供一個逆向工程，可以針對單表自動生成mybatis執行所需要的代碼（包括mapper.xml、mapper.java、po）。一般在開發中，常用的逆向工程方式是通過數據庫的表生成代碼。

二、逆向工程的作用

  通過表生成Mapper mapper.xml domain

三、怎麼使用逆向工程

1. 下載相關jar

2. 創建項目並導包

3. 創建generatorConfig 配置文件

<?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">  
<generatorConfiguration>  
<!-- 數據庫驅動-->  
    <classPathEntry  location="lib/mysql-connector-java-5.1.25-bin.jar"/>  
    <context id="DB2Tables"  targetRuntime="MyBatis3">  
        <commentGenerator>  
            <property name="suppressDate" value="true"/>  
            <!-- 是否去除自動生成的註釋 true：是 ： false:否 -->  
            <property name="suppressAllComments" value="true"/>  
        </commentGenerator>  
        <!--數據庫鏈接URL，用戶名、密碼 -->  
        <jdbcConnection driverClass="com.mysql.jdbc.Driver" connectionURL="jdbc:mysql://localhost/springdemo" userId="root" password="123456">  
        </jdbcConnection>  
        <!-- 處理oracle裏面的number類型的
        BigDecimal price === Oracle number(10,2)
         -->
        <javaTypeResolver>  
            <property name="forceBigDecimals" value="false"/>  
        </javaTypeResolver>  
        <!-- 生成模型的包名和位置-->  
        <javaModelGenerator targetPackage="com.lasing.domain" targetProject="src">  
            <property name="enableSubPackages" value="true"/>  
            <property name="trimStrings" value="true"/>  
        </javaModelGenerator>  
        <!-- 生成映射文件的包名和位置-->  
        <sqlMapGenerator targetPackage="com.lasing.mapping" targetProject="src">  
            <property name="enableSubPackages" value="true"/>  
        </sqlMapGenerator>  
        <!-- 生成Mapper的包名和位置-->  
        <javaClientGenerator type="XMLMAPPER" targetPackage="com.lasing.mapper" targetProject="src">  
            <property name="enableSubPackages" value="true"/>  
        </javaClientGenerator>  
        <!-- 要生成的表 tableName是數據庫中的表名或視圖名 domainObjectName是實體類名-->  
        <table tableName="user" domainObjectName="User" 
        	enableCountByExample="false" 
        	enableUpdateByExample="false" 
        	enableDeleteByExample="false" 
        	enableSelectByExample="false" 
        	selectByExampleQueryId="false">
        </table>
	</context>  
</generatorConfiguration>

4. 創建generatorSqlmap

package com.lasing.generator;
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 static void generator() throws Exception{
        List<String> warnings = new ArrayList<String>();
        boolean overwrite = true;
        //指定 逆向工程配置文件
        File configFile = new  File("config/generatorConfig.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) {
           try {
                generator();
                System.out.println("刷新成功，請刷新項目!");
           } catch (Exception e) {
                e.printStackTrace();
           }
     }
}

5. 運行generatorSqlmap 逆向生成 mapper、mapper.xml、實體類User

  出現這個之後刷新以下項目就行

6. 查看自動生成的文件

1. 自動生成的User實體類

package com.lasing.domain;

import java.util.Date;

public class User {
    private Integer id;

    private String name;

    private String address;

    private Date birthday;

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name == null ? null : name.trim();
    }

    public String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address == null ? null : address.trim();
    }

    public Date getBirthday() {
        return birthday;
    }

    public void setBirthday(Date birthday) {
        this.birthday = birthday;
    }
}

2. 自動生成的UserMapper

package com.lasing.mapper;

import com.lasing.domain.User;

public interface UserMapper {
    int deleteByPrimaryKey(Integer id);

    int insert(User record);

    int insertSelective(User record);

    User selectByPrimaryKey(Integer id);

    int updateByPrimaryKeySelective(User record);

    int updateByPrimaryKey(User record);
}

3. 自動生成的UserMapper.xml

<?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="com.lasing.mapper.UserMapper" >
  <resultMap id="BaseResultMap" type="com.lasing.domain.User" >
    <id column="id" property="id" jdbcType="INTEGER" />
    <result column="name" property="name" jdbcType="VARCHAR" />
    <result column="address" property="address" jdbcType="VARCHAR" />
    <result column="birthday" property="birthday" jdbcType="TIMESTAMP" />
  </resultMap>
  <sql id="Base_Column_List" >
    id, name, address, birthday
  </sql>
  <select id="selectByPrimaryKey" resultMap="BaseResultMap" parameterType="java.lang.Integer" >
    select 
    <include refid="Base_Column_List" />
    from user
    where id = #{id,jdbcType=INTEGER}
  </select>
  <delete id="deleteByPrimaryKey" parameterType="java.lang.Integer" >
    delete from user
    where id = #{id,jdbcType=INTEGER}
  </delete>
  <insert id="insert" parameterType="com.lasing.domain.User" >
    insert into user (id, name, address, 
      birthday)
    values (#{id,jdbcType=INTEGER}, #{name,jdbcType=VARCHAR}, #{address,jdbcType=VARCHAR}, 
      #{birthday,jdbcType=TIMESTAMP})s
  </insert>
  <insert id="insertSelective" parameterType="com.lasing.domain.User" >
    insert into user
    <trim prefix="(" suffix=")" suffixOverrides="," >
      <if test="id != null" >
        id,
      </if>
      <if test="name != null" >
        name,
      </if>
      <if test="address != null" >
        address,
      </if>
      <if test="birthday != null" >
        birthday,
      </if>
    </trim>
    <trim prefix="values (" suffix=")" suffixOverrides="," >
      <if test="id != null" >
        #{id,jdbcType=INTEGER},
      </if>
      <if test="name != null" >
        #{name,jdbcType=VARCHAR},
      </if>
      <if test="address != null" >
        #{address,jdbcType=VARCHAR},
      </if>
      <if test="birthday != null" >
        #{birthday,jdbcType=TIMESTAMP},
      </if>
    </trim>
  </insert>
  <update id="updateByPrimaryKeySelective" parameterType="com.lasing.domain.User" >
    update user
    <set >
      <if test="name != null" >
        name = #{name,jdbcType=VARCHAR},
      </if>
      <if test="address != null" >
        address = #{address,jdbcType=VARCHAR},
      </if>
      <if test="birthday != null" >
        birthday = #{birthday,jdbcType=TIMESTAMP},
      </if>
    </set>
    where id = #{id,jdbcType=INTEGER}
  </update>
  <update id="updateByPrimaryKey" parameterType="com.lasing.domain.User" >
    update user
    set name = #{name,jdbcType=VARCHAR},
      address = #{address,jdbcType=VARCHAR},
      birthday = #{birthday,jdbcType=TIMESTAMP}
    where id = #{id,jdbcType=INTEGER}
  </update>
</mapper>

7. 將自動生成的mapper、mapper.xml、實體類放到其他項目