mybatis-generator-plugin

1.背景

这篇文章刚开始想着哪个分类呢？mybatis、idea或是maven呢，最后还是选择了mybatis。最初使用这个逆向工具是在eclipse上，使用的是eclispe上mbg插件执行配置generatorConfig.xml文件；现在idea作为主力开发工具，而网上基本上都是介绍使用maven的mbg插件，而不是idea的插件执行generatorConfig.xml。本篇文章也是重复验证一下idea中maven使用mybatis-generator插件，至于idea的插件，最后试一下（其实另一篇文章已经介绍了一种easycode插件）。

2.工程结构

3.配置文件

generatorConfig.xml, 该文件是逆向工程核心文件，该实验中需要配置在pom.xml文件中；

<?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>
    <classPathEntry location="/Users/tusm/config/self_lib/mysql-connector-java-5.1.38.jar"/>
    <context id="default" targetRuntime="MyBatis3">
        <commentGenerator>
            <property name="suppressDate" value="true"/>
            <property name="suppressAllComments" value="true"/>
        </commentGenerator>
        <jdbcConnection driverClass="com.mysql.jdbc.Driver"
                        connectionURL="jdbc:mysql://192.168.3.32:3306/test"
                        userId="root"
                        password="123456">
        </jdbcConnection>
        <javaModelGenerator targetPackage="com.eran.bc.entity"
                            targetProject="./src/main/java">
            <property name="trimStrings" value="true"/>
        </javaModelGenerator>
        <sqlMapGenerator targetPackage="com.eran.bc.dao.mapper"
                         targetProject="./src/main/java">
        </sqlMapGenerator>
        <javaClientGenerator type="XMLMAPPER"
                             targetPackage="com.eran.bc.dao"
                             targetProject="./src/main/java">
        </javaClientGenerator>
        <table tableName="employee" domainObjectName="Employee"
               enableCountByExample="false" enableUpdateByExample="false"
               enableDeleteByExample="false" enableSelectByExample="false"
               selectByExampleQueryId="false">
        </table>
    </context>
</generatorConfiguration>

datasource.properties, 该文件为数据源配置文件；

jdbc.databaseurl=jdbc:mysql://192.168.3.32:3306/test
jdbc.driver=com.mysql.jdbc.Driver
jdbc.username=root
jdbc.password=123456

mybatis-config.xml, 该文件是mybatis框架工作核心文件；

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE configuration PUBLIC "-//mybatis.org//DTDConfig3.0//EN" "http://mybatis.org/dtd/mybatis-3-config.dtd">

<configuration>
    <properties resource="config/datasource.properties"></properties>
    <typeAliases>
        <!--别名方式1，一个一个的配置type中放置的是类的全路径，alias中放置的是类别名
        <typeAliasetype="com.mybatis.demo.Entity.User"alias="UserBean"/>-->
        <!--别名方式2，自动扫描，将JAVA类的类名作为类的类别名-->
        <!--<packagename="com.mybatis.demo.Entity"/>-->
        <typeAlias alias="Employee" type="com.eran.bc.entity.Employee"/>
    </typeAliases>

    <!--配置mybatis运行环境-->
    <environments default="development">
        <environment id="development">
            <!--type="JDBC"代表使用JDBC的提交和回滚来管理事务-->
            <transactionManager type="JDBC"/>

            <!--mybatis提供了3种数据源类型，分别是：POOLED,UNPOOLED,JNDI-->
            <!--POOLED表示支持JDBC数据源连接池-->
            <!--UNPOOLED表示不支持数据源连接池-->
            <!--JNDI表示支持外部数据源连接池-->
            <dataSource type="POOLED">
                <property name="driver" value="${jdbc.driver}"/>
                <property name="url" value="${jdbc.databaseurl}"/>
                <property name="username" value="${jdbc.username}"/>
                <property name="password" value="${jdbc.password}"/>
            </dataSource>
        </environment>
    </environments>

    <mappers>
        <!--映射文件方式1，一个一个的配置-->
        <mapper resource="mapper/EmployeeMapper.xml"/>  <!-- 放到之里就没事 -->
<!--        <mapper resource="com/eran/bc/dao/mapper/EmployeeMapper.xml"/>  放到dao/mapper包里报错BindingException，路径呀还是要弄明白-->
        <!--映射文件方式2，自动扫描包内的Mapper接口与配置文件-->
<!--        <package name="com/eran/bc/dao/mapper"/>-->
    </mappers>
</configuration>

pom.xml, 其中使用了mybatis-generator-maven-plugin插件

<?xml version="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>4.0.0</modelVersion>

  <groupId>com.eran.tools</groupId>
  <artifactId>blog-collection</artifactId>
  <version>1.0-SNAPSHOT</version>
  <packaging>war</packaging>

  <name>blog-collection Maven Webapp</name>
  <!-- FIXME change it to the project's website -->
  <url>http://www.example.com</url>

  <properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <maven.compiler.source>1.7</maven.compiler.source>
    <maven.compiler.target>1.7</maven.compiler.target>
  </properties>

  <dependencies>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>4.11</version>
      <scope>test</scope>
    </dependency>

    <dependency>
    <groupId>org.mybatis</groupId>
    <artifactId>mybatis</artifactId>
    <version>3.4.6</version>
  </dependency>

    <dependency>
      <groupId>mysql</groupId>
      <artifactId>mysql-connector-java</artifactId>
      <version>5.1.38</version>
    </dependency>

  </dependencies>

  <build>
    <finalName>blog-collection</finalName>
    <pluginManagement><!-- lock down plugins versions to avoid using Maven defaults (may be moved to parent pom) -->
      <plugins>
        <plugin>
          <artifactId>maven-clean-plugin</artifactId>
          <version>3.1.0</version>
        </plugin>
        <!-- see http://maven.apache.org/ref/current/maven-core/default-bindings.html#Plugin_bindings_for_war_packaging -->
        <plugin>
          <artifactId>maven-resources-plugin</artifactId>
          <version>3.0.2</version>
        </plugin>
        <plugin>
          <artifactId>maven-compiler-plugin</artifactId>
          <version>3.8.0</version>
        </plugin>
        <plugin>
          <artifactId>maven-surefire-plugin</artifactId>
          <version>2.22.1</version>
        </plugin>
        <plugin>
          <artifactId>maven-war-plugin</artifactId>
          <version>3.2.2</version>
        </plugin>
        <plugin>
          <artifactId>maven-install-plugin</artifactId>
          <version>2.5.2</version>
        </plugin>
        <plugin>
          <artifactId>maven-deploy-plugin</artifactId>
          <version>2.8.2</version>
        </plugin>
        <!-- mybatis-generator-maven-plugin不能放到这里，因为放了没有显示这个插件，对这个PluginManager使用还是不清楚 -->
      </plugins>
    </pluginManagement>
    <plugins>
      <plugin>
        <groupId>org.mybatis.generator</groupId>
        <artifactId>mybatis-generator-maven-plugin</artifactId>
        <version>1.3.2</version>
        <configuration>
          <configurationFile>src/main/resources/config/generatorConfig.xml</configurationFile>
          <verbose>true</verbose>
          <overwrite>true</overwrite>
        </configuration>
        <executions>
          <execution>
            <id>Generate MyBatis Artifacts</id>
            <goals>
              <goal>generate</goal>
            </goals>
          </execution>
        </executions>
        <dependencies>
          <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.38</version>
          </dependency>
        </dependencies>
      </plugin>
    </plugins>
  </build>
</project>

4.测试文件

package com.eran.bc.service;

import com.eran.bc.dao.EmployeeMapper;
import com.eran.bc.entity.Employee;
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.Reader;

public class EmployeeService {
    public static void main(String[] args) {
        /*
测试mbg
*/
        try {
            Reader reader = Resources.getResourceAsReader("config/mybatis-config.xml");
            SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(reader);
            SqlSession session = sessionFactory.openSession();
            EmployeeMapper mapper = session.getMapper(EmployeeMapper.class);
            Employee employee = mapper.selectByPrimaryKey(1);
            System.out.println(employee.getName());

            session.commit();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

5.使用idea插件逆向工程

1.其实上一篇博客https://www.cnblogs.com/leeethan/p/12197424.html，讲的easy code就是使用idea的插件配合database实现的逆向工程；

2.网上看到一个更好的插件idea-mybatis-generator，似乎更好，但我懒得去试了，这种东西基本差不多感觉。有兴趣自己去看看https://blog.csdn.net/qq_34208844/article/details/83819404

6.参考

Intellij IDEA中使用MyBatis-generator 插件自动生成MyBatis代码
源文档 <https://blog.csdn.net/xiao1_1bing/article/details/81944348> 

利用mybatis-generator自动生成代码
源文档 <https://www.cnblogs.com/deng-cc/p/9340748.html> 

通过idea-mybatis-generator插件生成实体和mapper
源文档 <https://blog.csdn.net/qq_34208844/article/details/83819404> 这个似乎是最简单的一个插件，集database+easycode的功能

7.注意事项

1.在mybatis-config.xml中的<mapper resource="com/eran/bc/dao/mapper/EmployeeMapper.xml"/>这么配置的话，会出现找不到该xml的报错。后来找到原因了。【解决办法】maven默认是不编译src/main/java中的xml文件，需要在maven->build标签中加入
<build>
<resources>
<!-- resources文件 -->
  <resource>
    <directory>src/main/java</directory>
    <!-- 引入映射文件等 -->
    <includes>
      <include>**/*.xml</include>
    </includes>
  </resource>
</resources>
</build>
解决链接：https://blog.csdn.net/chenmingxu438521/article/details/86768408