7. Mybatis 代码反向生成器(MBG)

一、插件的使用

描述: mybatis generator 的作用是根据数据库自动生成 实体类、Dao接口、Mapper 映射文件。
数据库：

create table product(
id int primary key AUTO_INCREMENT,
pname varchar(20),
price double,
category_id varchar(32)
);
INSERT INTO product(pname,price,category_id) VALUES('联想',5000,'电脑');
INSERT INTO product(pname,price,category_id) VALUES('海尔',3000,'洗衣机');
INSERT INTO product(pname,price,category_id) VALUES('雷神',5000,'笔记本');
INSERT INTO product(pname,price,category_id) VALUES('JACK JONES',800,'服饰');
INSERT INTO product(pname,price,category_id) VALUES('真维斯',200,'服饰');
INSERT INTO product(pname,price,category_id) VALUES('花花公子',440,'服饰');
INSERT INTO product(pname,price,category_id) VALUES('劲霸',2000,'服饰');
INSERT INTO product(pname,price,category_id) VALUES('香奈儿',800,'奢侈品');
INSERT INTO product(pname,price,category_id) VALUES('相宜本草',200,'亲民品');
INSERT INTO product(pname,price,category_id) VALUES('面霸',5,'垃圾');
INSERT INTO product(pname,price,category_id) VALUES('好想你枣',56,'零食');
INSERT INTO product(pname,price,category_id) VALUES('香飘飘奶茶',1,'毒药');
INSERT INTO product(pname,price,category_id) VALUES('果9',1,NULL);

步骤1：在pom.xml 中添加MBG插件

• pom.xml 中添加以下代码

 <plugin>
       <groupId>org.mybatis.generator</groupId>
       <artifactId>mybatis-generator-maven-plugin</artifactId>
       <version>1.4.0</version>
       <configuration>
      		 <configurationFile>${basedir}/src/main/resources/mybatis/generator/generatorConfig.xml</configurationFile>
			<!-- 设置覆盖原有的文件:第二次执行的时候 -->
       		<overwrite>true</overwrite>
       		<!-- 输出一些日志信息-->
       		<verbose>true</verbose>
       </configuration>

        <dependencies>
					<!-- maven 插件使用依赖包要独立设置 -->
                    <dependency>
                        <groupId>mysql</groupId>
                        <artifactId>mysql-connector-java</artifactId>
                        <version>5.1.48</version>
                    </dependency>
       </dependencies>
</plugin>

步骤2：编写 generatorConfig.xml 文件

• 在 src/main/resources/mybatis/generator目录下新建一个 generatorConfig.xml
  • 设置实体类、Mapper 映射文件、Dao 接口对应位置

<?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="MySQLTables" targetRuntime="MyBatis3">
		<!--  虽然插件中配置了<overwrite>true</overwrite>,但是只对java 文件有效,对mapper文件无效.特定使用 UnmergeableXmlMappersPlugin 才可以覆盖xml文件 -->
        <plugin type="org.mybatis.generator.plugins.UnmergeableXmlMappersPlugin" />
		<!--关闭注释的生成-->
        <commentGenerator>
            <property name="suppressAllComments" value="true"/>
        </commentGenerator>
        <!--覆盖生成XML文件-->
        <jdbcConnection driverClass="com.mysql.jdbc.Driver"
                        connectionURL="jdbc:mysql://127.0.0.1:3306/mybatisDemo"
                        userId="root"
                        password="root">
        </jdbcConnection>

        <javaTypeResolver >
            <property name="forceBigDecimals" value="false" />
        </javaTypeResolver>
        <!-- 实体类-->
        <javaModelGenerator targetPackage="net.suncaper.demo1.domain" targetProject="src/main/java">
            <property name="enableSubPackages" value="true" />
            <property name="trimStrings" value="true" />
        </javaModelGenerator>
        <!--Mapper 映射文件-->
        <sqlMapGenerator targetPackage="mybatis.mapper"  targetProject="src/main/resources">
            <property name="enableSubPackages" value="true" />
        </sqlMapGenerator>
		 <!--Mapper 到接口 -->
        <javaClientGenerator type="XMLMAPPER" targetPackage="net.suncaper.demo1.mapper"  targetProject="src/main/java">
            <property name="enableSubPackages" value="true" />
        </javaClientGenerator>

		<!--  对应的表生成对应的 实体类 -->
        <table tableName="product" domainObjectName="Product"/>

      <!--  <table schema="DB2ADMIN" tableName="ALLTYPES" domainObjectName="Customer" >
            <property name="useActualColumnNames" value="true"/>
            <generatedKey column="ID" sqlStatement="DB2" identity="true" />
            <columnOverride column="DATE_FIELD" property="startDate" />
            <ignoreColumn column="FRED" />
            <columnOverride column="LONG_VARCHAR_FIELD" jdbcType="VARCHAR" />
        </table>-->

    </context>
</generatorConfiguration>

• Mapper 映射文件

<select id="selectAllUser" resultMap="userMap">
    select * from `user`
</select>

• 测试代码

List<User> users = userMapper.selectAllUser();
for (User user : users) {
   System.out.println(user);
}

步骤3：通过运行maven 插件对应的方法

• 打开Idea 中maven 的视图 , Plugins → mybatis-generator → mybatis-generator:generator
• 截图