MyBatis代码实例系列-08：MyBatisGenerator插件及扩展(中文注释和Mapper重命名为Dao)

超级通道：MyBatis代码实例系列-绪论

本章主要记录如何使用Mybatis Generator，并在其基础上进行扩展优化，涉及到的技术有：
- MyBatis Generator：MyBatis代码自动生成插件，能够生成实体.java、实体Mapper.java和实体Mapper.xml，注释为英文
- [email protected]:li24361/mybatis-generator-core.git：开源插件，对MyBatis Generator进行了扩展，实现了中文注释，并将生成结果重命名为：实体Entity.java、实体Dao.java和实体Dao.xml。
- generatorConfig.xml：MyBatis Generator的配置文件。
- ToStringPlugin：MyBatis Generator的插件，在实体类中自动生成toString()方法。
- EqualsHashCodePlugin：MyBatis Generator的插件，在实体类中自动添加hashCode()和Equals()方法。

1.MyBatis Generator简介

在使用MyBatis框架进行开发时，每用到一张表就要手动创建实体类、XML映射文件和映射接口，这些都是重复性工作，耗费了我们大量精力。
MyBatis Generator (简称MBG) 是一个Mybatis的代码生成器。它可以根据数据库中的表，生成对应的实体类、XML映射文件和映射接口，节约了大量的时间去开发和业务逻辑有关的功能。
当然，如果是多表联合查询和存储过程，仍然需要手动处理。

2.通过Maven运行 MyBatis Generator

2.1.pom.xml

<dependency>
  <groupId>org.mybatis.generatorgroupId>
  <artifactId>mybatis-generator-coreartifactId>
  <version>1.3.6version>
dependency>

<plugins>
...
  <plugin>
    
    <groupId>org.mybatis.generatorgroupId>
    <artifactId>mybatis-generator-maven-pluginartifactId>
    <version>1.3.6version>
    <dependencies>
      
      <dependency>
        <groupId>mysqlgroupId>
        <artifactId>mysql-connector-javaartifactId>
        <version>${mysql.version}version>
      dependency>
    dependencies>
    <configuration>
        
        <configurationFile>src/main/resources/generatorConfig.xmlconfigurationFile>
        
        <overwrite>trueoverwrite>
        
        <verbose>trueverbose>
    configuration>
    
    <executions>
      <execution>
        <id>MyBatis Generatorid>
        <goals>
          <goal>generategoal>
        goals>
      execution>
    executions>
  plugin>
...
plugins>

2.2.MyBatis-generator配置文件：generatorConfig.xml

<generatorConfiguration>
    <properties resource="jdbc.properties"/>
    
    
    
    <context id="MysqlContext" targetRuntime="MyBatis3Simple" defaultModelType="flat">

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

        
        <plugin type="org.mybatis.generator.plugins.ToStringPlugin"/>
        
        <plugin type="org.mybatis.generator.plugins.EqualsHashCodePlugin"/>

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

        
        <jdbcConnection driverClass="${jdbc.driverClassName}"
                        connectionURL="${jdbc.url}"
                        userId="${jdbc.username}"
                        password="${jdbc.password}">
        jdbcConnection>

        
        
        
        <javaModelGenerator targetPackage="pers.hanchao.himybatis.generator.entity" targetProject="src\main\java">
            
            <property name="enableSubPackages" value="true"/>
            
            <property name="trimStrings" value="true" />
        javaModelGenerator>

        
        
        
        <sqlMapGenerator targetPackage="generator"  targetProject="src\main\resources">
            
            <property name="enableSubPackages" value="true"/>
        sqlMapGenerator>

        
        
        
        
        <javaClientGenerator type="XMLMAPPER" targetPackage="pers.hanchao.himybatis.generator.dao" targetProject="src\main\java">
            
            <property name="enableSubPackages" value="true"/>
        javaClientGenerator>

        
        
        
        
        <table schema="exam" tableName="topic">
            
            
            
            <generatedKey column="id" sqlStatement="Mysql"/>
        table>
    context>
generatorConfiguration>

2.3.运行MyBatis Generator

在IDEA中，点击Edit Configurations
–>添加一个Maven配置
–>录入Name
–>Command Line录入：mybatis-generator:generate
–>点击OK保存配置
–>点击或通过Alt+Shift+X运行这个Maven配置

2.4.生成结果

生成目录如下：

src
\---main
    \---java
    |   \---pers
    |       \---hanchao
    |           \---himybatis
    |               \---generator
    |                   \---dao
    |                   |   \---TopicMapper.java
    |                   |---entity
    |                       \---Topic.java
    \---webapp
        \---generator
            \---TopicMapper.xml

代码展示：
Topic.java
只详细展示第一个字段，后续字段和方法略。

package pers.hanchao.himybatis.generator.entity;

public class Topic {
    /**
     *
     * This field was generated by MyBatis Generator.
     * This field corresponds to the database column topic.id
     *
     * @mbg.generated
     */
    private Integer id;

    //other field

    //setter getter toString hashCode equals
}

TopicMapper.java
只详细展示第一个方法，后续方法略。

package pers.hanchao.himybatis.generator.dao;

import java.util.List;
import pers.hanchao.himybatis.generator.entity.Topic;

public interface TopicMapper {
    /**
     * This method was generated by MyBatis Generator.
     * This method corresponds to the database table topic
     *
     * @mbg.generated
     */
    int deleteByPrimaryKey(Integer id);

    //int insert(Topic record);
    //Topic selectByPrimaryKey(Integer id);
    //List selectAll();
    //int updateByPrimaryKey(Topic record);
}

TopicMapper.xml
只详细展示第一个方法，后续方法略。

<mapper namespace="pers.hanchao.himybatis.generator.dao.TopicMapper">
  <resultMap id="BaseResultMap" type="pers.hanchao.himybatis.generator.entity.Topic">
    
    <id column="id" jdbcType="INTEGER" property="id" />
    <result column="title" jdbcType="VARCHAR" property="title" />
    <result column="score" jdbcType="INTEGER" property="score" />
    <result column="answer" jdbcType="VARCHAR" property="answer" />
  resultMap>
  <delete id="deleteByPrimaryKey" parameterType="java.lang.Integer">
    
    delete from topic
    where id = #{id,jdbcType=INTEGER}
  delete>
  
mapper>

有待改进之处：

1. 生成的Topic.java和TopicMapper.java中的注释都是英文的，尤其是Topic.java的字段注释。这样对实际开发很不友好，还需要手动将所有的注释改为中文，不仅浪费时间，而且容易出错。
2. 我喜欢将实体Mapper重命名为XxxxDao.java或者XxxxIDAO，而非XxxxMapper.java，所以还需要手动将XxxxMapper全部修改为XxxxDao。

3.扩展MyBatis Generator

鉴于以上原因，很多大牛们通过修改MyBatis Generator源码或者新增实现类，提供了各种各样的解决方案。
本章只详细介绍其中的一种方案：由li24361提供的https://github.com/li24361/mybatis-generator-core

3.1.git clone

将mybatis-generator-core项目克隆到本地

git clone git@github.com:li24361/mybatis-generator-core.git

3.2.打成jar包到本地Repository

将mybatis-generator-core打成jar包并存放到本地仓库中

cd mybatis-generator-core/

mvn install -Dmaven.test.skip=true

3.3.修改pom.xml

注意：mybatis-generator-maven-plugin的版本号是1.3.2

<plugin>
  
  
  
  
  
    
    
      
      
      
    
  
  
  
  <groupId>org.mybatis.generatorgroupId>
  <artifactId>mybatis-generator-maven-pluginartifactId>
  <version>1.3.2version>
  <dependencies>
    
    <dependency>
      <groupId>mysqlgroupId>
      <artifactId>mysql-connector-javaartifactId>
      <version>${mysql.version}version>
    dependency>
    <dependency>
      <groupId>com.haier.hairygroupId>
      <artifactId>mybatis-generator-coreartifactId>
      <version>1.0.1version>
    dependency>
    dependencies>
        <configuration>
        
        <configurationFile>src/main/resources/generatorConfig.xmlconfigurationFile>
        
        <overwrite>trueoverwrite>
        
        <verbose>trueverbose>
     configuration>
  plugin>

3.4.修改generatorConfig.xml

<commentGenerator type="org.mybatis.generator.internal.HairyCommentGenerator">
    <property name="javaFileEncoding" value="UTF-8"/>
    
    <property name="suppressAllComments" value="false"/>
    
    <property name="suppressDate" value="true"/>
commentGenerator>

3.5.运行MyBatis Generator

3.6.生成结果

生成目录如下：

src
\---main
    \---java
    |   \---pers
    |       \---hanchao
    |           \---himybatis
    |               \---generator
    |                   \---dao
    |                   |   \---TopicDao.java
    |                   |---entity
    |                       \---TopicEntity.java
    \---webapp
        \---generator
            \---TopicDao.xml

代码展示：
TopicEntity.java
只详细展示第一个字段，后续字段和方法略。

package pers.hanchao.himybatis.generator.entity;

public class TopicEntity {
    /**
     * 
     * 话题
     * 表字段 : topic.id
     * 
     */
    private Integer id;

    //other fields

    //setter getter toString hashCode equals
}

TopicDao.java
只详细展示第一个方法，后续方法略。

package pers.hanchao.himybatis.generator.dao;

import java.util.List;
import pers.hanchao.himybatis.generator.entity.TopicEntity;

public interface TopicDao {
    /**
     * 根据主键删除数据库的记录
     *
     * @param id
     */
    int deleteByPrimaryKey(Integer id);

    //int insert(Topic record);
    //Topic selectByPrimaryKey(Integer id);
    //List selectAll();
    //int updateByPrimaryKey(Topic record);
}

TopicDao.xml的内容和之前一样，不再赘述。

---

总结：通过使用由li24361提供的https://github.com/li24361/mybatis-generator-core，确实达到了之前的目的：

• 生成可用的中文注释
• 更符合开发习惯的命名规范：TopicEntity.java、TopicDao.java、TopicDao.xml

4.测试生成代码的可用性

通过简单的TopicApp.java完成对生成的TopicEntity.java、TopicDao.java、TopicDao.xml可用性测试。

TopicApp.java

package pers.hanchao.himybatis.generator;

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 org.apache.log4j.Logger;
import pers.hanchao.himybatis.generator.dao.TopicDao;
import pers.hanchao.himybatis.generator.entity.TopicEntity;

import java.io.IOException;
import java.io.Reader;

/**
 * 
测试MyBatis Generator生成的代码是否可用
 * @author hanchao 2018/2/4 10:45
 **/
public class TopicApp {
    /** 日志 */
    private static final Logger LOGGER = Logger.getLogger(TopicApp.class);

    /** 配置文件读取类 */
    private static Reader reader;

    /** 会话工厂 */
    private static SqlSessionFactory sqlSessionFactory;

    static {
        try {
            //读取配置文件
            reader = Resources.getResourceAsReader("mybatis-config-generator.xml");
            //构建会话工厂
            sqlSessionFactory = new SqlSessionFactoryBuilder().build(reader);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    /**
     * 
对MyBatis Generator生成的数据库方法进行测试
     * @author hanchao 2018/2/4 10:46
     **/
    public static void main(String[] args) {
        //创建会话
        SqlSession sqlSession = sqlSessionFactory.openSession();
        try {
            //获取Dao层实例
            TopicDao topicDao = sqlSession.getMapper(TopicDao.class);
            //查询所有
            LOGGER.info("查询所有");
            LOGGER.info(topicDao.selectAll());
            //插入一个，查询所有
            System.out.println();
            LOGGER.info("插入一个");
            TopicEntity newTopic = new TopicEntity();
            newTopic.setId(100);
            newTopic.setTitle("新增的标题");
            newTopic.setScore(200);
            newTopic.setAnswer("新增的答案");
            topicDao.insert(newTopic);
            LOGGER.info(topicDao.selectAll());
            //查询一个
            System.out.println();
            LOGGER.info("查询一个");
            LOGGER.info(topicDao.selectByPrimaryKey(1));
            //修改一个，然后查询
            System.out.println();
            LOGGER.info("修改一个");
            newTopic = new TopicEntity();
            newTopic.setId(1);
            newTopic.setTitle("修改的标题");
            newTopic.setScore(1000);
            newTopic.setAnswer("修改的答案");
            topicDao.updateByPrimaryKey(newTopic);
            LOGGER.info(topicDao.selectByPrimaryKey(1));
            //删除一个，然后查询
            System.out.println();
            LOGGER.info("删除一个，然后查询");
            topicDao.deleteByPrimaryKey(1);
            LOGGER.info(topicDao.selectByPrimaryKey(1));

            //提交
            sqlSession.commit();
        }catch (Exception e){
            e.printStackTrace();
            LOGGER.info("error!");
            sqlSession.rollback();
        }finally {
            sqlSession.close();
        }
    }
}

运行结果：

2018-02-04 16:38:59 INFO  TopicApp:49 - 查询所有
2018-02-04 16:38:59 DEBUG JdbcTransaction:54 - Opening JDBC Connection
2018-02-04 16:39:00 DEBUG PooledDataSource:54 - Created connection 1316864772.
2018-02-04 16:39:00 DEBUG JdbcTransaction:54 - Setting autocommit to false on JDBC Connection [com.mysql.jdbc.JDBC4Connection@4e7dc304]
2018-02-04 16:39:00 DEBUG selectAll:54 - ==>  Preparing: select id, title, score, answer from topic 
2018-02-04 16:39:00 DEBUG selectAll:54 - ==> Parameters: 
2018-02-04 16:39:00 DEBUG selectAll:54 - <==      Total: 2
2018-02-04 16:39:00 INFO  TopicApp:50 - [TopicEntity [Hash = -756562783, id=1, title=新话题1111, score=1001111, answer=新答案111], TopicEntity [Hash = 1936880702, id=99999, title=题目1, score=100, answer=你好吗？]]

2018-02-04 16:39:00 INFO  TopicApp:53 - 插入一个
2018-02-04 16:39:00 DEBUG insert!selectKey:54 - ==>  Preparing: SELECT LAST_INSERT_ID() 
2018-02-04 16:39:00 DEBUG insert!selectKey:54 - ==> Parameters: 
2018-02-04 16:39:00 DEBUG insert!selectKey:54 - <==      Total: 1
2018-02-04 16:39:00 DEBUG insert:54 - ==>  Preparing: insert into topic (id, title, score, answer) values (?, ?, ?, ?) 
2018-02-04 16:39:00 DEBUG insert:54 - ==> Parameters: 0(Integer), 新增的标题(String), 200(Integer), 新增的答案(String)
2018-02-04 16:39:00 DEBUG insert:54 - <==    Updates: 1
2018-02-04 16:39:00 DEBUG selectAll:54 - ==>  Preparing: select id, title, score, answer from topic 
2018-02-04 16:39:00 DEBUG selectAll:54 - ==> Parameters: 
2018-02-04 16:39:00 DEBUG selectAll:54 - <==      Total: 3
2018-02-04 16:39:00 INFO  TopicApp:60 - [TopicEntity [Hash = -756562783, id=1, title=新话题1111, score=1001111, answer=新答案111], TopicEntity [Hash = 1936880702, id=99999, title=题目1, score=100, answer=你好吗？], TopicEntity [Hash = -1744254903, id=100001, title=新增的标题, score=200, answer=新增的答案]]

2018-02-04 16:39:00 INFO  TopicApp:63 - 查询一个
2018-02-04 16:39:00 DEBUG selectByPrimaryKey:54 - ==>  Preparing: select id, title, score, answer from topic where id = ? 
2018-02-04 16:39:00 DEBUG selectByPrimaryKey:54 - ==> Parameters: 1(Integer)
2018-02-04 16:39:00 DEBUG selectByPrimaryKey:54 - <==      Total: 1
2018-02-04 16:39:00 INFO  TopicApp:64 - TopicEntity [Hash = -756562783, id=1, title=新话题1111, score=1001111, answer=新答案111]

2018-02-04 16:39:00 INFO  TopicApp:67 - 修改一个
2018-02-04 16:39:00 DEBUG updateByPrimaryKey:54 - ==>  Preparing: update topic set title = ?, score = ?, answer = ? where id = ? 
2018-02-04 16:39:00 DEBUG updateByPrimaryKey:54 - ==> Parameters: 修改的标题(String), 1000(Integer), 修改的答案(String), 1(Integer)
2018-02-04 16:39:00 DEBUG updateByPrimaryKey:54 - <==    Updates: 1
2018-02-04 16:39:00 DEBUG selectByPrimaryKey:54 - ==>  Preparing: select id, title, score, answer from topic where id = ? 
2018-02-04 16:39:00 DEBUG selectByPrimaryKey:54 - ==> Parameters: 1(Integer)
2018-02-04 16:39:00 DEBUG selectByPrimaryKey:54 - <==      Total: 1
2018-02-04 16:39:00 INFO  TopicApp:74 - TopicEntity [Hash = 1122539663, id=1, title=修改的标题, score=1000, answer=修改的答案]

2018-02-04 16:39:00 INFO  TopicApp:77 - 删除一个，然后查询
2018-02-04 16:39:00 DEBUG deleteByPrimaryKey:54 - ==>  Preparing: delete from topic where id = ? 
2018-02-04 16:39:00 DEBUG deleteByPrimaryKey:54 - ==> Parameters: 1(Integer)
2018-02-04 16:39:00 DEBUG deleteByPrimaryKey:54 - <==    Updates: 1
2018-02-04 16:39:00 DEBUG selectByPrimaryKey:54 - ==>  Preparing: select id, title, score, answer from topic where id = ? 
2018-02-04 16:39:00 DEBUG selectByPrimaryKey:54 - ==> Parameters: 1(Integer)
2018-02-04 16:39:00 DEBUG selectByPrimaryKey:54 - <==      Total: 0
2018-02-04 16:39:00 INFO  TopicApp:79 - 

5.参考资料与更多扩展

参考资料：

1. 官方半中文网
2. MyBatis学习之代码生成器Generator
3. https://github.com/li24361/mybatis-generator-core
4. mybatis-generator代码生成解决生成数据库的注释
5. MyBatis Generator 详解

更多扩展：

1. mybatis-generator-gui：基于mybatis generator开发一款界面工具
2. MyBatis Generator 插件的拓展插件包：MySQL分页插件、查询单条数据插件等等