MyBatis逆向工程

主要特点

需要程序员自己编写sql,如果表太多的话，难免会很麻烦，所以MyBatis官方提供了一个逆向工程，可以针对单表自动生成MyBatis执行所需要的代码 (包括mapper.xml(映射文件)、mapper.java(接口)、pojo(实体类文件))
一般在开发中，常用的逆向工程方式是通过数据库的表生成代码。

步骤

1. 创建一个Maven工程
2. 引入使用的jar包
3. 添加配置文件 generatorConfig.xml
   (设置数据库的驱动、配置、包名、文件保存位置、表名等)
4. 定义GeneratorSqlmap类，调用MyBatis自动创建接口，在main方法执行自动创建

一、创建一个maven工程

二、pom.xml文件中导入依赖

<dependencies>
 	<dependency>
	    <groupId>mysql</groupId>
	    <artifactId>mysql-connector-java</artifactId>
	    <version>5.1.47</version>
	</dependency>
	<dependency>
	    <groupId>org.mybatis</groupId>
	    <artifactId>mybatis</artifactId>
	    <version>3.2.6</version>
	</dependency>		
	<dependency>
		<groupId>org.mybatis.generator</groupId>
	    <artifactId>mybatis-generator-core</artifactId>
	    <version>1.3.2</version>
	</dependency>
</dependencies> 

三、添加配置文件

<?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="testTables" targetRuntime="MyBatis3">
		<commentGenerator>
			<!-- 是否去除自动生成的注释 true：是 ： false:否 -->
			<property name="suppressAllComments" value="true" />
		</commentGenerator>
		<!--数据库连接的信息：驱动类、连接地址、用户名、密码 -->
		<jdbcConnection driverClass="com.mysql.jdbc.Driver"
			connectionURL="jdbc:mysql://localhost:3306/cyl" userId="root"
			password="root">
		</jdbcConnection>
		 <!-- <jdbcConnection driverClass="oracle.jdbc.OracleDriver"
			connectionURL="jdbc:oracle:thin:@10.10.21.3:1521:orcl" 
			userId="scott"
			password="tiger">
		</jdbcConnection> --> 

		<!-- 默认false，把JDBC DECIMAL 和 NUMERIC 类型解析为 Integer，为 true时把JDBC DECIMAL 和 
			NUMERIC 类型解析为java.math.BigDecimal -->
		<javaTypeResolver>
			<property name="forceBigDecimals" value="false" />
		</javaTypeResolver>

		<!-- targetProject:生成PO类的位置 -->
		<javaModelGenerator targetPackage="com.beans"
			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>
        <!-- targetProject:mapper映射文件生成的位置 -->
		<sqlMapGenerator targetPackage="mapping" 
			targetProject=".\src\main\resources">
			<!-- enableSubPackages:是否让schema作为包的后缀 -->
			<property name="enableSubPackages" value="false" />
		</sqlMapGenerator>
		<!-- targetPackage：mapper接口生成的位置 -->
		<javaClientGenerator type="XMLMAPPER"
			targetPackage="com.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="userinfo" 
			domainObjectName="UserInfo"
			enableCountByExample="false" 
			enableUpdateByExample="false" 
			enableDeleteByExample="false"    
            enableSelectByExample="false" 
            selectByExampleQueryId="false" >
            
            <columnOverride column="id" javaType="Integer" />
         
         </table>
		
	</context>
</generatorConfiguration>

四、创建一个GeneratorSqlmap.java文件

import java.util.ArrayList;
import java.util.List;

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;

public class GeneratorSqlmap {
	public void generator() throws  Exception{
		List<String> warnings = new ArrayList<String>();
		boolean overwrite = true;
		File configFile = new File("src/main/resources/generatorConfig.xml");
		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) throws Exception {
		GeneratorSqlmap g = new GeneratorSqlmap();
		g.generator();
		System.out.println("OK");
	}
}

五、点击运行一下这个类，自动创建

六、点击工程右键refresh

会自动生成

七、创建mybatis-config.xml和mydbconfig.properties文件

mybatis-config.xml

<?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>	

	<properties resource="mydbconfig.properties" />
	<environments default="development">    
		<environment id="development">  
			<transactionManager type="JDBC"/>  
			<dataSource type="POOLED">   
				<property name="driver" value="${db.driver}"/>  
				<property name="url" value="${db.url}"/>  
				<property name="username" value="${db.username}" />  
				<property name="password" value="${db.password}" />  
			</dataSource>  
		</environment>  
	</environments> 
	<mappers>
		<mapper resource="mapping/UserInfoMapper.xml"/> 
	</mappers>	
</configuration>

mydbconfig.properties

db.driver=com.mysql.jdbc.Driver
db.url=jdbc:mysql://localhost:3306/cyl
db.username=root
db.password=root

八、创建测试类

package com.mapper;

import java.io.InputStream;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import org.junit.Test;

import com.beans.UserInfo;
public class UserInfoMapperTest {
	
	public static void main(String[] args) {
		SqlSession sqlSession = null;
		UserInfoMapper mapper = null;
		InputStream in = Test.class.getClassLoader().getResourceAsStream("mybatis-config.xml");
		SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder();
		SqlSessionFactory factory = builder.build(in);
		sqlSession = factory.openSession();
		mapper = sqlSession.getMapper(UserInfoMapper.class);
		
		UserInfo userInfo = mapper.selectByPrimaryKey(2);
		System.out.println(userInfo);
		
		UserInfo user = new UserInfo();
		user.setUserName("lifeng");
		user.setPassword("123");
		int result = mapper.insert(user);
		if(result!=0)
		{
			System.out.println("ok");
		}
		sqlSession.commit();
		sqlSession.close();
	}
	

}

九、运行成功