mybatis中的 mybatis-generator:generate 代码生成器的使用

超、凢脫俗 2022-05-28 01:11 226阅读 0赞

mybatis当中 有 非常方便快捷使用的 generator，代码生成器，方便开发者使用

具体使用方法如下：

首先，我们创建一个maven项目，如下图所示：

![SouthEast][]

pom.xml 文件中进行如下的配置:

<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>mybatisGenerator</groupId>
      <artifactId>mybatisGeneratortest</artifactId>
      <version>0.0.1-SNAPSHOT</version>
      
      
      
      
      	
      	
      	<properties>
            <java.version>1.8</java.version>
            <java.encoding>UTF-8</java.encoding>
        </properties>
      
      
        <dependencies>
            
            <dependency>
                <groupId>org.mybatis</groupId>
                <artifactId>mybatis</artifactId>
                <version>3.4.2</version>
            </dependency>
    
            <dependency>
                <groupId>org.projectlombok</groupId>
                <artifactId>lombok</artifactId>
                <version>1.16.6</version>
            </dependency>
    
        
             <dependency>
                 <groupId>mysql</groupId>
                 <artifactId>mysql-connector-java</artifactId>
                 <version>5.1.26</version>
             </dependency>
             
        </dependencies>
    
        <build>
            <plugins>
                <plugin>
                    <groupId>org.mybatis.generator</groupId>
                    <artifactId>mybatis-generator-maven-plugin</artifactId>
                    <version>1.3.3</version>
                    <configuration>
                        <configurationFile>src/test/resources/generatorConfig.xml</configurationFile>
                        <overwrite>true</overwrite>
                    </configuration>
                </plugin>
                
                
                
            </plugins>
            
            
        </build>
      
    </project>

mybatis-config.xml 主配置文件如下:

<?xml version="1.0" encoding="UTF-8"?>
    <!DOCTYPE configuration
      PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
      "http://mybatis.org/dtd/mybatis-3-config.dtd">
    <configuration>
    
      
    	<environments default="development">
        <environment id="development">
          <transactionManager type="JDBC"/>
          <dataSource type="POOLED">
            
            <property name="driver" value="com.mysql.jdbc.Driver"/>
            <property name="url" value="jdbc:mysql://localhost:3306/test"/>
            <property name="username" value="root"/>
            <property name="password" value="root"/>
            
          </dataSource>
        </environment>
      </environments>
      
      
      <mappers>
      	<mapper resource="com/zwz/mapper/UserMapper.xml" />
      </mappers>
    	
    </configuration>

生成器配置 xml文件 generatorConfig.xml文件：

<?xml version="1.0" encoding="UTF-8"?>
    
    <!DOCTYPE generatorConfiguration
            PUBLIC "-//mybatis.org//DTD MyBatis Generator Configuration 1.0//EN"
            "mybatis-generator-config_1_0.dtd">
    
    <generatorConfiguration>
        <classPathEntry location="F:\myeclipse_workspace\gupao-springmvc\gupao-generator\src\main\resources\mybatis\mysql-connector-java-5.1.8.jar"/>
    
        <context id="MysqlTables" targetRuntime="MyBatis3">
            
            <commentGenerator>
                <property name="suppressAllComments" value="true"/>
            </commentGenerator>
    
            <jdbcConnection driverClass="com.mysql.jdbc.Driver"
                            connectionURL="jdbc:mysql://localhost:3306/test"
                            userId="root"
                            password="root">
            </jdbcConnection>
    
            <javaTypeResolver>
                <property name="forceBigDecimals" value="false"/>
            </javaTypeResolver>
    
            <javaModelGenerator targetPackage="com.zwz.entity" targetProject="F:\myeclipse_workspace\mybatisGeneratortest\src\main\java">
                <property name="enableSubPackages" value="true"/>
                <property name="trimStrings" value="true"/>
            </javaModelGenerator>
    
            <sqlMapGenerator targetPackage="com.zwz.mapper" targetProject="F:\myeclipse_workspace\mybatisGeneratortest\src\main\java">
                <property name="enableSubPackages" value="true"/>
            </sqlMapGenerator>
    
            <javaClientGenerator type="XMLMAPPER" targetPackage="com.zwz.dao" targetProject="F:\myeclipse_workspace\mybatisGeneratortest\src\main\java">
                <property name="enableSubPackages" value="true"/>
            </javaClientGenerator>
    
    
    	
    		<table schema="gp" tableName="user" domainObjectName="User">
                <property name="useActualColumnNames" value="false"/>
                
                <columnOverride column="DATE_FIELD" property="startDate"/>
                <ignoreColumn column="FRED"/>
                <columnOverride column="LONG_VARCHAR_FIELD" jdbcType="VARCHAR"/>
            </table>
    
    
        </context>
    </generatorConfiguration>

在项目中右键，run as --> maven build ,然后在 goals当中输入 mybatis-generator:generate,于是便可以看到 在相对应配置的包目录下生成了对应的 实体类，Mapper文件，Mapper.xml文件,如下：

![SouthEast 1][]

最后一步，编写测试类进行mybatis的测试:

mybatisDemo文件如下：

package com.zwz.test;
    
    import java.io.FileInputStream;
    import java.io.FileNotFoundException;
    import java.io.InputStream;
    
    import org.apache.ibatis.session.SqlSession;
    import org.apache.ibatis.session.SqlSessionFactory;
    import org.apache.ibatis.session.SqlSessionFactoryBuilder;
    
    import com.zwz.dao.UserMapper;
    import com.zwz.entity.User;
    
    
    public class MybatisDemo {
    
    	//获取到sqlSession
    	public static SqlSession getSqlSession() throws Exception{
    		InputStream configFile = new FileInputStream(
                    "F:\\myeclipse_workspace\\mybatisGeneratortest\\src\\test\\resources\\mybatis-config.xml");
    		
            SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(configFile);
            
            //加载配置文件得到SqlSessionFactory
            return sqlSessionFactory.openSession();
    	}
    	
    	public static void main(String[] args) throws Exception {
    		
    		SqlSession sqlSession = getSqlSession();
    		
    		UserMapper um = sqlSession.getMapper(UserMapper.class);
    		
    		User user = um.selectByPrimaryKey("2");
    		
    		System.out.println(  user.getName() );
    		
    	}
    	
    }

测试后输出正确结果，是数据库当中的信息。

生成了代码之后，可以在此基础上使用  UserExample的  Criteria  进行结果的查询，查询的代码如下：

public static void main(String[] args) throws Exception {
    	
    		UserExample userExample = new UserExample(); 
    		
    		userExample.setOrderByClause("id desc"); //设置排序规则
    		
    		userExample.createCriteria().andAgeBetween("2", "3");	//创建 Criteria 并且设置查询规则
    		
    		UserMapper um = getSqlSession().getMapper( UserMapper.class ); //设置好了之后从 SqlSession 中获取到这个 UserMapper的实例对象
    		
    		List<User>list = um.selectByExample(userExample);	//查询实例
    	
    		for(User u:list){
    			System.out.println( u.getName() );
    		}
    		
    		userExample.clear();	//执行了这句clear之后代表着 userExample接下来就可以进行复用了，不受之前添加条件的影响
    	
    		System.out.println("--------------------------------");
    		
    		
    		userExample.createCriteria().andIdGreaterThan("2");
    		UserMapper um1 = getSqlSession().getMapper( UserMapper.class );
    		
    		List<User>list2 = um1.selectByExample(userExample);
    	
    		for(User u:list2){
    			System.out.println( u.getName() );
    		}
    		
    	}

[SouthEast]: /images/20220528/c0d42d7972c34d93899d865f2e77ad76.png
[SouthEast 1]: /images/20220528/c0601b7fb77549e588884d8f7dfbcc2b.png