mybatis generator为实体类生成自定义注释（读取数据库字段的注释添加到实体类，不修改源码）

我们都知道mybatis generator自动生成的注释没什么实际作用，而且还增加了代码量。如果能将注释从数据库中捞取到，不仅能很大程度上增加代码的可读性，而且减少了后期手动加注释的工作量。

1、首先定义注释生成插件

MyCommentGenerator.java

package com.ilovey.mybatis.comment;

import org.mybatis.generator.api.IntrospectedColumn;
import org.mybatis.generator.api.IntrospectedTable;
import org.mybatis.generator.api.dom.java.Field;
import org.mybatis.generator.api.dom.java.InnerClass;
import org.mybatis.generator.api.dom.java.Method;
import org.mybatis.generator.internal.DefaultCommentGenerator;

import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Properties;

/**
 * mybatis generator生成注释插件
 * <p>
 * Created by huhaichao on 2017/5/15.
 */
public class MyCommentGenerator extends DefaultCommentGenerator {
    private Properties properties;
    private Properties systemPro;
    private boolean suppressDate;
    private boolean suppressAllComments;
    private String currentDateStr;

    public MyCommentGenerator() {
        super();
        properties = new Properties();
        systemPro = System.getProperties();
        suppressDate = false;
        suppressAllComments = false;
        currentDateStr = (new SimpleDateFormat("yyyy-MM-dd")).format(new Date());
    }

    public void addFieldComment(Field field, IntrospectedTable introspectedTable,
                                IntrospectedColumn introspectedColumn) {
        if (suppressAllComments) {
            return;
        }
        StringBuilder sb = new StringBuilder();
        field.addJavaDocLine("/**");
        sb.append(" * ");
        sb.append(introspectedColumn.getRemarks());
        field.addJavaDocLine(sb.toString().replace("\n", " "));
        field.addJavaDocLine(" */");
    }

    public void addFieldComment(Field field, IntrospectedTable introspectedTable) {

    }

    public void addGeneralMethodComment(Method method, IntrospectedTable introspectedTable) {

    }

    public void addGetterComment(Method method, IntrospectedTable introspectedTable,
                                 IntrospectedColumn introspectedColumn) {

    }

    public void addSetterComment(Method method, IntrospectedTable introspectedTable,
                                 IntrospectedColumn introspectedColumn) {

    }

    public void addClassComment(InnerClass innerClass, IntrospectedTable introspectedTable, boolean markAsDoNotDelete) {

    }

    public void addClassComment(InnerClass innerClass, IntrospectedTable introspectedTable) {
    }

}

2、然后为mybatisgenerator配置插件

<?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>
    <context id="context1">
        <plugin type="org.mybatis.generator.plugins.SerializablePlugin"/>

        <!-- 使用自定义的插件 -->
        <commentGenerator type="com.ilovey.mybatis.comment.MyCommentGenerator">

        </commentGenerator>

        <jdbcConnection driverClass="com.mysql.jdbc.Driver"
         connectionURL="jdbc:mysql://localhost:3306/test?useUnicode=true&amp;characterEncoding=UTF8"
         userId="root" password="123456">
        </jdbcConnection>

        <javaModelGenerator targetPackage="com.ilovey.biz.entity.base"
         targetProject="ilovey.biz/src/main/java"/>
        <sqlMapGenerator targetPackage="com.ilovey.biz.mapper.base"
         targetProject="ilovey.biz/src/main/resources"/>
        <javaClientGenerator targetPackage="com.ilovey.biz.mapper.base"
         targetProject="ilovey.biz/src/main/java" type="XMLMAPPER"/>

        <table tableName="us_user_info"  domainObjectName="UsUserInfo">
            <generatedKey column="id" sqlStatement="MySql" identity="true"/>
        </table>

    </context>
</generatorConfiguration>

3、使用mybatis generator自动生成代码

由于使用的是maven项目，而且使用了了自定义的插件，所以采用 main方法启动，适用场景更对，而且能将代码生成到对应的工程目录下，免去拷贝的过程（当然也可以用maven插件、控制台、eclipse插件等多种方式启动）。

注意：当前类所在的工程要添加mybatis generator的依赖包

启动类如下

package com.ilovey.mybatis;

import org.mybatis.generator.api.MyBatisGenerator;
import org.mybatis.generator.config.Configuration;
import org.mybatis.generator.config.xml.ConfigurationParser;
import org.mybatis.generator.internal.DefaultShellCallback;

import java.io.InputStream;
import java.util.ArrayList;
import java.util.List;

/**
 * 运行此方法生成mybatis代码
 * 生成代码自动放入对应目录
 * 配置文件targetProject应从项目名称开始到要生成到的classpath
 * Created by huhaichao on 2017/5/15.
 */
public class MyBatisGeneratorRun {

    public static void main(String[] args) throws Exception{
        MyBatisGeneratorRun app = new MyBatisGeneratorRun();

        System.out.println(app.getClass().getResource("/").getPath());
        app.generator();
        System.out.println(System.getProperty("user.dir"));
    }

    public void generator() throws Exception{

        List<String> warnings = new ArrayList<String>();
        boolean overwrite = true;
        InputStream resourceAsStream = this.getClass().getClassLoader().getResourceAsStream("generatorConfig.xml");
        ConfigurationParser cp = new ConfigurationParser(warnings);
        Configuration config = cp.parseConfiguration(resourceAsStream);
        DefaultShellCallback callback = new DefaultShellCallback(overwrite);
        MyBatisGenerator myBatisGenerator = new MyBatisGenerator(config, callback, warnings);
        myBatisGenerator.generate(null);

        for(String warning:warnings){
            System.out.println(warning);
        }
    }
}

再贴下项目的maven依赖，有需要的可以看下

<?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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>party.lovey</groupId>
    <artifactId>generator</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>

    <dependencies>
        <dependency>
            <groupId>org.mybatis.generator</groupId>
            <artifactId>mybatis-generator-core</artifactId>
            <version>1.3.6</version>
        </dependency>

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.29</version>
        </dependency>
    </dependencies>

</project>

4、生成效果

package com.ilovey.biz.entity.base;

import java.io.Serializable;
import java.util.Date;

public class UsUserInfo implements Serializable {
    /**
     *
     */
    private Integer id;

    /**
     * 用户id
     */
    private Integer userId;

    /**
     * 昵称
     */
    private String nickName;

    /**
     * 头像
     */
    private String headImage;

    /**
     * 手机号码
     */
    private String mobile;

    /**
     * 性别（0保密，1男，2女）
     */
    private Integer sex;

    /**
     * 地区
     */
    private Integer region;

    /**
     * 个性签名
     */
    private String signature;

    /**
     * 创建时间
     */
    private Date createTime;

    /**
     * 更新时间
     */
    private Date updateTime;

    //setter 和 getter方法省略
}

此外，mybatis的插件还有着更强大的功能，比如支持分页功能，修复因别名造成的delete语句错误等，需要这些插件的朋友可以在底部留言。

原文地址：https://www.cnblogs.com/cblogs/p/9432129.html