main函数生成：
工程代码demo：

1. 添加依赖

<dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.0</version>
        </dependency>

        <dependency>
            <groupId>org.mybatis.generator</groupId>
            <artifactId>mybatis-generator-core</artifactId>
            <version>1.3.7</version>
        </dependency>

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.40</version>
        </dependency>

2. 代码生成配置文件 generatorConfig.xml
   （按需更改配置）

<?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>

    <classPathEntry
    location="F:\maven_local_repository\mysql\mysql-connector-java\5.1.40\mysql-connector-java-5.1.40.jar"/>


    <context id="MySqlContext" targetRuntime="MyBatis3" defaultModelType="flat">

        <!-- beginningDelimiter/endingDelimiter: 指明数据库的用于标记数据库对象名的符号，比如ORACLE是双引号，MYSQL默认是`反引号  -->
        <property name="beginningDelimiter" value="`"/>
        <property name="endingDelimiter" value="`"/>
        <!-- 生成的Java文件的编码 -->
        <property name="javaFileEncoding" value="UTF-8"/>
        <plugin type="org.mybatis.generator.plugins.EqualsHashCodePlugin"/>
        <plugin type="org.mybatis.generator.plugins.ToStringPlugin"/>

        <!-- 删除自动生成注释 -->
        <commentGenerator>
            <property name="suppressAllComments" value="true" />
        </commentGenerator>

        <!-- 配置数据库连接信息 -->
        <jdbcConnection
                driverClass="com.mysql.jdbc.Driver"
                connectionURL="jdbc:mysql://127.0.0.1:3306/mooc_one"
                userId="root"
                password="root">
        </jdbcConnection>

        <!-- 自动生成实体类存放的位置 -->
        <javaModelGenerator targetPackage="com.mybatis.generator.entity"
                            targetProject="src\main\java">
            <!-- enableSubPackages:是否让schema作为包的后缀 -->
            <property name="enableSubPackages" value="false" />
            <!-- 从数据库返回的值被清理前后的空格 -->
            <property name="trimStrings" value="true" />
        </javaModelGenerator>

        <!-- 自动生成Mapper.xml存放的位置 -->
        <sqlMapGenerator targetPackage="mappers"
                         targetProject="src\main\resources">
            <!-- enableSubPackages:是否让schema作为包的后缀 -->
            <property name="enableSubPackages" value="false" />
        </sqlMapGenerator>

        <!-- 自动生成Mapper接口存放的位置 -->
        <javaClientGenerator type="XMLMAPPER"
                             targetPackage="com.mybatis.generator.mapper"
                             targetProject="src\main\java">
            <!-- enableSubPackages:是否让schema作为包的后缀 -->
            <property name="enableSubPackages" value="false" />
        </javaClientGenerator>

        <!-- 指定数据库表 -->
        <table tableName="item_info" domainObjectName="ItemInfo">
            <generatedKey column="id" sqlStatement="MySql"/>
        </table>

        <!--<table tableName="%">-->
            <!--<generatedKey column="id" sqlStatement="MySql"/>-->
        <!--</table>-->

    </context>
</generatorConfiguration>

3. main函数

public class GeneratorMain {

    public void generator() throws Exception {
        List<String> warnings = new ArrayList<String>();
        boolean overwrite = true;
        // 指定配置文件
        String genCfg = "/generatorConfig.xml";
        File configFile = new File(GeneratorMain.class.getResource(genCfg).getFile());
        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) {
        try {
            GeneratorMain generatorSqlmap = new GeneratorMain();
            generatorSqlmap.generator();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

}

插件生成

<plugin>
                <groupId>org.mybatis.generator</groupId>
                <artifactId>mybatis-generator-maven-plugin</artifactId>
                <version>1.3.2</version>
                <!--配置文件所在位置-->
                <configuration>
                    <configurationFile>src/main/resources/generatorConfig.xml</configurationFile>
                    <verbose>true</verbose>
                    <overwrite>true</overwrite>
                </configuration>
            </plugin>