下例仅供参考
数据库的数据
主机：172.xx.xxx.xx
端口:666
用户名:root
密码:root
需要生成代码的表单名:one

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1.给Spring Tool Suite安装插件
Hellp-->Eclipse Marketplace...-->新页面的搜索框输入"mybatis"-->选择最新的"MyBatis Generator1.4.0",点击"installed"安装

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2.generatorConfig.xml文件 
结构：项目/src/main/resources/generatorConfig.xml
代码：
<?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>
    <!-- 数据库驱动:选择你的本地硬盘上面的数据库驱动包-->
    <classPathEntry location="C:\Users\user\.m2\repository\mysql\mysql-connector-java\8.0.15\mysql-connector-java-8.0.15-sources.jar"/>


    <context id="DB2Tables" targetRuntime="MyBatis3">
        <!-- JavaBean 实现 序列化 接口 -->
        <plugin type="org.mybatis.generator.plugins.SerializablePlugin" />
        <!-- 生成toString -->
        <plugin type="org.mybatis.generator.plugins.ToStringPlugin" />
        <!-- optional，旨在创建class时，对注释进行控制 -->
        <commentGenerator>
            <property name="suppressDate" value="true"/>
            <!-- <property name="suppressAllComments" value="true"/>-->
        </commentGenerator>


        <!--数据库链接URL，用户名、密码 -->
        <jdbcConnection driverClass="com.mysql.cj.jdbc.Driver"
                        connectionURL="jdbc:mysql://主机名：端口号/redmine?useSSL=false&amp;characterEncoding=UTF-8&amp;serverTimezone=UTC"
                        userId="用户名"
                      password="密码">
                  <property name="nullCatalogMeansCurrent" value="true"/>
        </jdbcConnection>


        <!-- 类型转换 -->
        <javaTypeResolver >
            <!-- 是否使用bigDecimal,
                false: 把JDBC DECIMAL 和 NUMERIC 类型解析为 Integer(默认)
                true:  把JDBC DECIMAL 和 NUMERIC 类型解析为java.math.BigDecimal
            -->
            <property name="forceBigDecimals" value="false" />
        </javaTypeResolver>


        <!-- 生成模型的包名和位置-->
        <javaModelGenerator targetPackage="com.example.demo.database" targetProject="项目名/src/main/java">
            <!-- 默认false 是否允许子包 -->
            <property name="enableSubPackages" value="true" />
            <!-- 默认false 是否对model添加 构造函数 -->
            <property name="constructorBased" value="false"/>
            <!-- 默认false 建立的Model对象是否 不可改变  即生成的Model对象不会有 setter方法，只有构造方法 -->
            <property name="immutable" value="false"/>
            <!-- 默认false 是否对类CHAR类型的列的数据进行trim操作 -->
            <property name="trimStrings" value="true" />
        </javaModelGenerator>
        <!-- 生成映射文件的包名和位置-->
        <sqlMapGenerator targetPackage="文件名字" targetProject="项目名/src/main/resources">
            <property name="enableSubPackages" value="true"/>
        </sqlMapGenerator>
        <!-- 生成DAO的包名和位置-->
        <javaClientGenerator type="XMLMAPPER" targetPackage="com.example.demo.database" targetProject="项目名/src/main/java">
            <property name="enableSubPackages" value="true"/>
        </javaClientGenerator>
        <!-- 要生成的表 tableName是数据库中的表名或视图名 domainObjectName是实体类名-->
       <!-- <table tableName="表名" domainObjectName="id" enableCountByExample="false" enableUpdateByExample="false" enableDeleteByExample="false" enableSelectByExample="false" selectByExampleQueryId="false"></table>
        <table tableName="tel_bill_record" domainObjectName="DSTelBillRecord" enableCountByExample="false" enableUpdateByExample="false" enableDeleteByExample="false" enableSelectByExample="false" selectByExampleQueryId="false"></table>-->
        <table tableName="这里填需要生成的表名one"></table>
        
    </context>
</generatorConfiguration>

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项目名/pom.xml
<?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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>
	<parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>2.4.0</version>
		<relativePath /> <!-- lookup parent from repository -->
	</parent>
	<groupId>com.example</groupId>
	<artifactId>项目名</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<name>项目名</name>
	<description>Demo project for Spring Boot</description>

	<properties>
		<java.version>本地java的版本</java.version>
	</properties>

	<dependencies>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-web</artifactId>
		</dependency>

		<dependency>
			<groupId> org.springframework.boot </groupId>
			<artifactId> spring-boot-starter-logging </artifactId>
		</dependency>

		<dependency>
			<groupId>org.mybatis.spring.boot</groupId>
			<artifactId>mybatis-spring-boot-starter</artifactId>
			<version>2.1.3</version>
		</dependency>

		<dependency>
			<groupId>org.projectlombok</groupId>
			<artifactId>lombok</artifactId>
			<optional>true</optional>
		</dependency>

		<dependency>
			<groupId>org.apache.commons</groupId>
			<artifactId>commons-lang3</artifactId>
		</dependency>

		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-test</artifactId>
			<scope>test</scope>
		</dependency>

		<dependency>
			<groupId>com.alibaba</groupId>
			<artifactId>fastjson</artifactId>
			<version>1.2.54</version>
		</dependency>

		<dependency>
			<groupId>mysql</groupId>
			<artifactId>mysql-connector-java</artifactId>
			<version>8.0.15</version>
		</dependency>

		<dependency>
			<groupId>be.yildiz-games</groupId>
			<artifactId>module-database-postgresql</artifactId>
			<version>1.0.9</version>
		</dependency>

		<dependency>
			<groupId>org.modelmapper</groupId>
			<artifactId>modelmapper</artifactId>
			<version>2.3.9</version>
		</dependency>

		<dependency>
			<groupId>com.github.pagehelper</groupId>
			<artifactId>pagehelper-spring-boot-starter</artifactId>
			<version>1.2.13</version>
		</dependency>
	</dependencies>
	<build>
		<plugins>
			<plugin>
				<groupId>org.springframework.boot</groupId>
				<artifactId>spring-boot-maven-plugin</artifactId>
			</plugin>
			<plugin>
				<groupId>org.mybatis.generator</groupId>
				<artifactId>mybatis-generator-maven-plugin</artifactId>
				<version>1.3.7</version>
				<configuration>
					<verbose>true</verbose>
					<overwrite>true</overwrite>
				</configuration>
				<dependencies>
					<dependency>
						<groupId>be.yildiz-games</groupId>
						<artifactId>module-database-postgresql</artifactId>
						<version>1.0.9</version>
					</dependency>
					<dependency>
						<groupId>mysql</groupId>
						<artifactId>mysql-connector-java</artifactId>
						<version>8.0.15</version>
					</dependency>		
				
				</dependencies>
			</plugin>
		</plugins>
	</build>
</project>

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运行并生成代码：选中generatorConfig.xml-->右键选Run as-->1 run mybatis Generator