如何用MyBatis－Generator自动创建代码(映射生成实体类、DAO接口和Mapping映射文件)

布满荆棘的人生 2022-06-08 06:08 213阅读 0赞

# 如何用MyBatis自动生成实体类、DAO接口和Mapping映射文件 #

## 引言： ##

**什么是 MyBatis ？**

*  MyBatis 是一款优秀的持久层框架，它支持定制化 SQL、存储过程以及高级映射。MyBatis 避免了几乎所有的 JDBC 代码和手动设置参数以及获取结果集。MyBatis 可以使用简单的 XML 或注解来配置和映射原生信息，将接口和 Java 的 POJOs(Plain Old Java Objects,普通的 Java对象)映射成数据库中的记录。
 *  描述来自官网：[http://www.mybatis.org/mybatis-3/zh/getting-started.html][http_www.mybatis.org_mybatis-3_zh_getting-started.html]

如果你了解JPA、Hibernate等持久层框架(规范)，那么你就大概知道MyBatis在开发中处于哪一环节了。

那么MyBatis是不是也可以像JPA、Hibernate那样映射生成数据库、实体类呢？**答案是肯定的。**  
官方早已打包好了jar包来支持我们提高开发效率了：

**MyBatis Generator** \- a code generator for MyBatis and iBatis.

--------------------

下面介绍如何用MyBatis－generator自动映射生成实体类:

## 准备： ##

case: ( Postgresql )  
1. 下载**mybatis-generator.jar**包：[http://mvnrepository.com/artifact/org.mybatis.generator/mybatis-generator-core/1.3.5][http_mvnrepository.com_artifact_org.mybatis.generator_mybatis-generator-core_1.3.5]  
2. **JDBC-Driver**:[https://jdbc.postgresql.org/download.html][https_jdbc.postgresql.org_download.html]  
3. 创建编辑**generatorConfig.xml**文件(稍后介绍) **\[\*3\]**  
4. Database ready.**\[\*4\]**  
5. 一个基于**MyBatis**的项目.

**\[\*3\]**  
generatorConfig.xml内容如下：

<?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="postgresql-9.4.1210.jre6.jar" />
        <context id="DB2Tables" targetRuntime="MyBatis3">
            <commentGenerator>
                <property name="suppressDate" value="true" />
                
                <property name="suppressAllComments" value="true" />
            </commentGenerator>
            
            <jdbcConnection driverClass="org.postgresql.Driver" connectionURL="jdbc:postgresql://localhost:5432/springlearn" userId="postgres" password="postgres">
            </jdbcConnection>
            <javaTypeResolver>
                <property name="forceBigDecimals" value="false" />
            </javaTypeResolver>
            
            <javaModelGenerator targetPackage="site.gaoyisheng.pojo" targetProject="src/main/java">
                <property name="enableSubPackages" value="true" />
                <property name="trimStrings" value="true" />
            </javaModelGenerator>
            
            <sqlMapGenerator targetPackage="site.gaoyisheng.dao.mapping" targetProject="src/main/java/">
                <property name="enableSubPackages" value="true" />
            </sqlMapGenerator>
            
            <javaClientGenerator type="XMLMAPPER" targetPackage="site.gaoyisheng.dao" targetProject="src/main/java/">
                <property name="enableSubPackages" value="true" />
            </javaClientGenerator>
            
            <table tableName="user" domainObjectName="User" enableCountByExample="false" enableUpdateByExample="false" enableDeleteByExample="false" enableSelectByExample="false" selectByExampleQueryId="false"></table>
        </context>
    </generatorConfiguration>

**Change** to your Configurations :

1:
    
    
    2:
    
    
    3:
     *3
    <targetPackage="site.gaoyisheng.XX" targetProject="src/main/java/">
    
    4:

**\[\*4\]**  
Database and Table :

*  DB named ‘**springlearn**’
 *  Table named ‘**user**’  
    ![这里写图片描述][SouthEast]

**\[\*5\]**  
Directory Structure :  
![这里写图片描述][SouthEast 1]

## Generate： ##

![这里写图片描述][SouthEast 2]

java -jar mybatis-generator-core-1.3.5.jar -configfile generatorConfig.xml -overwrite

Finished Directory Structure :  
![这里写图片描述][SouthEast 3]

View source code in :  
[https://github.com/timo1160139211/ejos-inSpring][https_github.com_timo1160139211_ejos-inSpring]

参考资料：  
1. [http://blog.csdn.net/zhshulin/article/details/23912615][http_blog.csdn.net_zhshulin_article_details_23912615]  
2. [http://www.cnblogs.com/xdp-gacl/p/4261895.html][http_www.cnblogs.com_xdp-gacl_p_4261895.html]  
3. [http://www.zuidaima.com/share/2148093791816704.htm][http_www.zuidaima.com_share_2148093791816704.htm]  
4. [http://www.zuidaima.com/share/3516663465790464.htm][http_www.zuidaima.com_share_3516663465790464.htm] Java方法实现的  
2. [http://www.mybatis.org/mybatis-3/zh/index.html][http_www.mybatis.org_mybatis-3_zh_index.html]

[http_www.mybatis.org_mybatis-3_zh_getting-started.html]: http://www.mybatis.org/mybatis-3/zh/getting-started.html
[http_mvnrepository.com_artifact_org.mybatis.generator_mybatis-generator-core_1.3.5]: http://mvnrepository.com/artifact/org.mybatis.generator/mybatis-generator-core/1.3.5
[https_jdbc.postgresql.org_download.html]: https://jdbc.postgresql.org/download.html
[SouthEast]: /images/20220608/00205b5bf68d4a8ea8846c7c9ba48563.png
[SouthEast 1]: /images/20220608/5a38ee1d7c39410bb4dd39f6c2cdb957.png
[SouthEast 2]: /images/20220608/74b3bf8556bc44a78f6e5bf2c485ed99.png
[SouthEast 3]: /images/20220608/a43eed6fa7474350b6f1e2d76701d56e.png
[https_github.com_timo1160139211_ejos-inSpring]: https://github.com/timo1160139211/ejos-inSpring
[http_blog.csdn.net_zhshulin_article_details_23912615]: http://blog.csdn.net/zhshulin/article/details/23912615
[http_www.cnblogs.com_xdp-gacl_p_4261895.html]: http://www.cnblogs.com/xdp-gacl/p/4261895.html
[http_www.zuidaima.com_share_2148093791816704.htm]: http://www.zuidaima.com/share/2148093791816704.htm
[http_www.zuidaima.com_share_3516663465790464.htm]: http://www.zuidaima.com/share/3516663465790464.htm
[http_www.mybatis.org_mybatis-3_zh_index.html]: http://www.mybatis.org/mybatis-3/zh/index.html