Mybatis Generator 是mybatis 逆向插件，可以通过数据库的表逆向生成pojo类，以及dao层和相应的mapper.xml文件。十分的方便，能很有效的减少代码书写量。不过一般都是使用配置xml的方式，通过maven的方式来运行的。具体请参看我上一篇文章：https://www.jianshu.com/p/b4609ca6ca33

我也是找了好久才再mybatis的官网上找到了有关纯java类执行generator的方式。具体看连接如下：http://www.mybatis.org/generator/running/runningWithJava.html

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看到了我红线标注的地方了么，这里才是有关java配置generatorConfig.xml的地方。可惜的是，忽略了很多的信息，对于我这种新手来说。最不擅长看官方文档了，所以很难才能找到这里。
查看文档，大体上官方文档给出的意思是，在相应的方法中，将下面的代码写入，然后再在注释的地方进行详细的配置。我具体的java配置如下：

package com.snowy.fastgov.generator;

import org.mybatis.generator.api.MyBatisGenerator;
import org.mybatis.generator.config.*;
import org.mybatis.generator.exception.InvalidConfigurationException;
import org.mybatis.generator.internal.DefaultShellCallback;

import java.io.IOException;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;

public class GeneratorConfig {


    private String driverClass = "com.mysql.cj.jdbc.Driver";

    private String connectionURL = "jdbc:mysql://localhost:3306/any?useUnicode=true&characterEncoding=utf8";

    private String userId = "root";

    private String password = "root";


    private String targetPackage = "com.snowy.fastgov.common.entity";

    private String targetProject = "src/main/java";


    private String sqlTargetPackage = "mapping";

    private String sqlTargetProject = "src/main/resources";


    private String daoTargetPackage = "com.snowy.fastgov.common.mapper";

    private String daoTargetProject = "src/main/java";

    private String classpathEntry="E:\\IdeaProject\\fastgov\\src\\main\\resources\\webapp\\lib\\mysql-connector-java-5.1.43.jar";


    public static void main(String[] args){
        GeneratorConfig generatorConfig = new GeneratorConfig();
        TableEntity tableEntity = new TableEntity();
        tableEntity.setTableName("good");
        tableEntity.setDomainObjectName("Good");
        List<TableEntity> list = new ArrayList<>();
        list.add(tableEntity);
        generatorConfig.generatorConfig(list);
    }

    public void generatorConfig(List<TableEntity> tableList) {

        List<String> warnings = new ArrayList<String>();
        boolean overwrite = true;
        Context context = new Context(ModelType.CONDITIONAL);
        context.setTargetRuntime("MyBatis3");
        context.setId("mysql");
        

        CommentGeneratorConfiguration commentGeneratorConfiguration = new CommentGeneratorConfiguration();
        commentGeneratorConfiguration.addProperty("suppressDate","true");
        commentGeneratorConfiguration.addProperty("suppressAllComments","true");

        /*数据库链接URL，用户名、密码 */
        JDBCConnectionConfiguration jdbcConnectionConfiguration = new JDBCConnectionConfiguration();
        jdbcConnectionConfiguration.setDriverClass(driverClass);
        jdbcConnectionConfiguration.setConnectionURL(connectionURL);
        jdbcConnectionConfiguration.setUserId(userId);
        jdbcConnectionConfiguration.setPassword(password);

        JavaTypeResolverConfiguration javaTypeResolverConfiguration = new JavaTypeResolverConfiguration();
        javaTypeResolverConfiguration.addProperty("forceBigDecimals","false");

        /*生成模型的包名和位置*/
        JavaModelGeneratorConfiguration javaModelGeneratorConfiguration = new JavaModelGeneratorConfiguration();
        javaModelGeneratorConfiguration.setTargetPackage(targetPackage);
        javaModelGeneratorConfiguration.setTargetProject(targetProject);
        javaModelGeneratorConfiguration.addProperty("enableSubPackages","true");
        javaModelGeneratorConfiguration.addProperty("trimStrings","true");

        /*生成映射文件的包名和位置*/
        SqlMapGeneratorConfiguration sqlMapGeneratorConfiguration = new SqlMapGeneratorConfiguration();
        sqlMapGeneratorConfiguration.setTargetPackage(sqlTargetPackage);
        sqlMapGeneratorConfiguration.setTargetProject(sqlTargetProject);
        sqlMapGeneratorConfiguration.addProperty("enableSubPackages","true");

        /*生成DAO的包名和位置*/
        JavaClientGeneratorConfiguration javaClientGeneratorConfiguration = new JavaClientGeneratorConfiguration();
        javaClientGeneratorConfiguration.setConfigurationType("XMLMAPPER");
        javaClientGeneratorConfiguration.setTargetPackage(daoTargetPackage);
        javaClientGeneratorConfiguration.setTargetProject(daoTargetProject);
        javaClientGeneratorConfiguration.addProperty("enableSubPackages","true");


        context.setCommentGeneratorConfiguration(commentGeneratorConfiguration);
        context.setJdbcConnectionConfiguration(jdbcConnectionConfiguration);
        context.setJavaTypeResolverConfiguration(javaTypeResolverConfiguration);
        context.setJavaModelGeneratorConfiguration(javaModelGeneratorConfiguration);
        context.setSqlMapGeneratorConfiguration(sqlMapGeneratorConfiguration);
        context.setJavaClientGeneratorConfiguration(javaClientGeneratorConfiguration);
        

        tableList.stream().forEach(tableEntity->{
            TableConfiguration tableConfiguration = new TableConfiguration(context);
            tableConfiguration.setTableName(tableEntity.getTableName());
            tableConfiguration.setDomainObjectName(tableEntity.getDomainObjectName());
            context.addTableConfiguration(tableConfiguration);
        });

        Configuration config = new Configuration();
        config.addClasspathEntry(classpathEntry);
        config.addContext(context);

        DefaultShellCallback callback = new DefaultShellCallback(overwrite);
        MyBatisGenerator myBatisGenerator = null;
        try {
            myBatisGenerator = new MyBatisGenerator(config, callback, warnings);
            myBatisGenerator.generate(null);
        } catch (InvalidConfigurationException e) {
            e.printStackTrace();
        } catch (InterruptedException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } catch (SQLException e) {
            e.printStackTrace();
        }

    }
}

TableEntity实体类

package com.snowy.fastgov.generator;

import lombok.Data;

@Data
public class TableEntity {
    private String tableName;
    private String domainObjectName;
}

导入mybatis generator 的maven依赖之后，把局部变量的内容更换城你自己的运行maim方法即可。