首先创建一个MAVEN项目

在pom.xml中添加如下依赖

<dependencies>
        <dependency>
        <groupId>org.mybatis.generator</groupId>
        <artifactId>mybatis-generator-core</artifactId>
        <version>1.3.5</version>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
            <scope>compile</scope>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.21</version>//mysql对应的版本，需要注意的
        </dependency>
    </dependencies>

从MyBatis官网看配置文件(http://mybatis.org/generator/quickstart.html#MyBatis3)

并创建配置文件generatorConfig.xml（官网有模板的）
jdbcConnection driverClass="com.mysql.cj.jdbc.Driver"注意这个是对应mysql8.0版本的

<!DOCTYPE generatorConfiguration PUBLIC
        "-//mybatis.org//DTD MyBatis Generator Configuration 1.0//EN"
        "http://mybatis.org/dtd/mybatis-generator-config_1_0.dtd">
<generatorConfiguration>
<!--MyBatis3Simple：生成简单版的CRUD
MyBatis：生成复杂版
-->
<context id="DB2Tables" targetRuntime="MyBatis3Simple">
    <!--jdbcConnection：指定如何连接到目标数据库-->
    <jdbcConnection driverClass="com.mysql.cj.jdbc.Driver"
                    connectionURL="jdbc:mysql://localhost/atcrowdfunding_test?useUnicode=true&amp; characterEncoding=UTF-8&amp; userSSL=false&amp; serverTimezone=GMT%2B8"
                    userId="root"
                    password="123456">
    </jdbcConnection>

    <!--javaTypeResolver:java类型的解析器-->
    <javaTypeResolver >
        <property name="forceBigDecimals" value="false" />
    </javaTypeResolver>

    <!--javaModelGenerator:指定javaBean的生成策略
    targetPackage:目标包名
    targetProject：目标工程
    -->
    <javaModelGenerator targetPackage="com.atguigu.atcrowdfunding.bean"
                        targetProject="src\main\java">
        <property name="enableSubPackages" value="true" />
        <property name="trimStrings" value="true" />
    </javaModelGenerator>

    <!--sqlMapGenerator:sql映射生成策略-->
    <sqlMapGenerator targetPackage="example.mapper"
                     targetProject="src\main\resources">
        <property name="enableSubPackages" value="true" />
    </sqlMapGenerator>

    <!--javaClientGenerator:指定mapper接口所在的位置-->
    <javaClientGenerator type="XMLMAPPER"
                         targetPackage="com.atguigu.atcrowdfunding.manager.dao"
                         targetProject="src\main\java">
        <property name="enableSubPackages" value="true" />
    </javaClientGenerator>

    <!--table：逆向分析哪些表，根据表创建javaBean-->
    <table tableName="t_account_type_cert" domainObjectName="AccountTypeCert"></table>
    <table tableName="t_advertisement" domainObjectName="Advertisement"></table>
    <table tableName="t_cert" domainObjectName="Cert"></table>
    <table tableName="t_dictionary" domainObjectName="Distionary"></table>
    <table tableName="t_member" domainObjectName="Member"></table>
    <table tableName="t_member_address" domainObjectName="MemberAddress"></table>
    <table tableName="t_member_cert" domainObjectName="MemberCert"></table>
    <table tableName="t_member_project_follow" domainObjectName="MemberProjectFollow"></table>
    <table tableName="t_message" domainObjectName="Message"></table>
    <table tableName="t_order" domainObjectName="Order"></table>
    <table tableName="t_param" domainObjectName="Param"></table>
    <table tableName="t_permission" domainObjectName="Permission"></table>
    <table tableName="t_project" domainObjectName="Project"></table>
    <table tableName="t_project_tag" domainObjectName="ProjectTag"></table>
    <table tableName="t_project_type" domainObjectName="ProjectType"></table>
    <table tableName="t_return" domainObjectName="Return"></table>
    <table tableName="t_role" domainObjectName="Role"></table>
    <table tableName="t_role_permission" domainObjectName="RolePermission"></table>
    <table tableName="t_tag" domainObjectName="Tag"></table>
    <table tableName="t_type" domainObjectName="Type"></table>
    <table tableName="t_user" domainObjectName="User"></table>
    <table tableName="t_user_role" domainObjectName="UserRole"></table>
    </context>
</generatorConfiguration>

然后编写一个类（方法可从官网上获取）

public static void runMBG() throws Exception {
        List<String> warnings = new ArrayList<String>();
        boolean overwrite = true;
        File configFile = new File("generatorConfig.xml");
        ConfigurationParser cp = new ConfigurationParser(warnings);
        Configuration config = cp.parseConfiguration(configFile);
        DefaultShellCallback callback = new DefaultShellCallback(overwrite);
        MyBatisGenerator myBatisGenerator = new MyBatisGenerator(config, callback, warnings);
        myBatisGenerator.generate(null);
    }

    public static void main(String[] args) throws Exception {
        runMBG();
    }

然后运行即可