MyBatis逆向工程generatorConfig配置文件的Table中generatedKey的作用

     Mybatis逆向工程生成Entity,Mapper等文件，在有自增ID的时候，在generatorConfig.xml中对表的配置，都要加上一行        generatedKey，如下：

  <table tableName="DICTIONARY_SUMMARY"  enableCountByExample="false" enableUpdateByExample="false"
       enableDeleteByExample="false" enableSelectByExample="false" selectByExampleQueryId="false">
       
           <generatedKey column="ID" sqlStatement="Mysql" identity="true"/>
           
  </table>

这样做的意义是，调用mapper插入一条数据到数据库之后，能从当前这个Entity中获取到插入之后的Id,如下：

1：在generatorConfig.xml中没有添加generatedKey，获得的ID为null

2：在generatorConfig.xml中添加generatedKey，获得的ID为数据库中的ID

数据库：

generatorConfig.xml文件如下：

<?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>
	<properties resource="mapper.properties"/>
	
	<context id="Mysql" targetRuntime="MyBatis3Simple" defaultModelType="flat" >
		<property name="beginningDelimiter" value="`"/>
        <property name="endingDelimiter" value="`"/>
        
        <plugin type="tk.mybatis.mapper.generator.MapperPlugin">
            <property name="mappers" value="ef.accounting_core.util.BaseMapper"/>
            <property name="caseSensitive" value="true"/>
        </plugin>
		
		<commentGenerator>
			<property name ="suppressDate" value="false"/>
			<property name="suppressAllComments" value="false"/>
			<property name="javaFileEncoding" value="UTF-8"/>
		</commentGenerator>
		
		<!-- 
		connectionURL="jdbc:mysql://192.168.20.125:3306/CF_TEST_DB?useSSL=false" 
		 -->
		<jdbcConnection connectionURL="${spring.datasource.url}"
						driverClass="${spring.datasource.driver-class-name}"
		  				userId="${spring.datasource.username}"
		  				password="${spring.datasource.password}">
		  		<property name="nullCatalogMeansCurrent" value="true"/>
		</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="true"/>
            <!-- This property is used to specify whether MyBatis Generator should force the use of JSR-310 data types for DATE, TIME,
            and TIMESTAMP fields, rather than using java.util.Date -->
            <property name="useJSR310Types" value="true"/>
        </javaTypeResolver>
	  
	  	<javaModelGenerator targetPackage="ef.accounting_core.entity" targetProject="src/main/java" />
	  	<sqlMapGenerator targetPackage="mapper" targetProject="src/main/resources" />
	  	<javaClientGenerator targetPackage="ef.accounting_core.mapper" targetProject="src/main/java" type="XMLMAPPER" />

	   <!--在 pom.xml 这一级目录的命令行窗口先执行 
	   		set MAVEN_OPTS="-Dfile.encoding=UTF-8" 
	   		解决中文乱码问题
	   		再执行 
	   		mvn mybatis-generator:generate 
	     -->
	   	
<!-- 	   <table tableName="ORG_CON_FILE"  enableCountByExample="false" enableUpdateByExample="false"
	   enableDeleteByExample="false" enableSelectByExample="false" selectByExampleQueryId="false">
	   	</table> -->

	   <table tableName="DICTIONARY_SUMMARY"  enableCountByExample="false" enableUpdateByExample="false"
	   enableDeleteByExample="false" enableSelectByExample="false" selectByExampleQueryId="false">
	   
		   <generatedKey column="ID" sqlStatement="Mysql" identity="true"/>
		   
	   	</table>
	</context>
</generatorConfiguration>