1 项目目录结构
2 maven依赖
除了mybatis必要的包之外，还需要添加逆向工程的插件包
<dependencies>
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis</artifactId>
<version>3.4.5</version>
</dependency>
<dependency>
<groupId>org.mybatis.generator</groupId>
<artifactId>mybatis-generator</artifactId>
<version>1.3.6</version>
</dependency>
<dependency>
<groupId>org.mybatis.generator</groupId>
<artifactId>mybatis-generator-maven-plugin</artifactId>
<version>1.3.6</version>
</dependency>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.12</version>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.37</version>
</dependency>
<dependency>
<groupId>log4j</groupId>
<artifactId>log4j</artifactId>
<version>1.2.12</version>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.6.1</version>
<configuration>
<source>1.8</source>
<target>1.8</target>
</configuration>
</plugin>
</plugins>
</build>
3 mybatis配置文件
这个案例只是一个简单的demo，所以mybatis-config.xml进行一些简单的配置即可
<?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>
<settings>
<setting name="mapUnderscoreToCamelCase" value="true"/>
</settings>
<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?characterEncoding=utf-8"/>
<property name="username" value="root"/>
<property name="password" value=""/>
</dataSource>
</environment>
</environments>
<mappers>
<mapper class="com.lrm.mapper.UserMapper"/>
</mappers>
</configuration>
4 逆向工程配置文件
也就是目录结构中的mgb.xml
<?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="DB2Tables" targetRuntime="MyBatis3">
<commentGenerator>
<!-- 是否去除自动生成的注释 true：是 ： false:否 -->
<property name="suppressAllComments" value="true" />
</commentGenerator>
<!-- jdbcConnection：指定如何连接到目标数据库 -->
<jdbcConnection driverClass="com.mysql.jdbc.Driver"
connectionURL="jdbc:mysql://localhost:3306/test?allowMultiQueries=true"
userId="root"
password="">
</jdbcConnection>
<!-- 转换器 -->
<javaTypeResolver >
<property name="forceBigDecimals" value="false" />
</javaTypeResolver>
<javaModelGenerator targetPackage="com.lrm.domain"
targetProject="Mybatis_4\src\main\java">
<property name="enableSubPackages" value="false" />
<property name="trimStrings" value="true" />
</javaModelGenerator>
<!-- sqlMapGenerator：sql映射生成策略： -->
<sqlMapGenerator targetPackage="com.lrm.mapper"
targetProject="Mybatis_4\src\main\java">
<property name="enableSubPackages" value="true" />
</sqlMapGenerator>
<!-- javaClientGenerator:指定mapper接口所在的位置 -->
<javaClientGenerator type="XMLMAPPER" targetPackage="com.lrm.mapper"
targetProject="Mybatis_4\src\main\java">
<property name="enableSubPackages" value="true" />
</javaClientGenerator>
<!-- 指定要逆向分析哪些表：根据表要创建javaBean -->
<table tableName="user" domainObjectName="User"></table>
</context>
</generatorConfiguration>
5 创建数据表
根据实际情况创建数据表即可
6 生成器配置类
package com.lrm.test;
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.File;
import java.util.ArrayList;
import java.util.List;
public class Generator {
public void generator() throws Exception{
List<String> warnings = new ArrayList<String>();
boolean overwrite = true;
/** 指向逆向工程配置文件 */
File configFile = new File("Mybatis_4/src/main/resources/mbg.xml");
ConfigurationParser parser = new ConfigurationParser(warnings);
Configuration config = parser.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 {
try {
Generator generatorSqlmap = new Generator();
generatorSqlmap.generator();
} catch (Exception e) {
e.printStackTrace();
}
}
}
运行main方法，即可生成数据表对于bean文件、mapper接口和mapper配置文件。
7 测试
package com.lrm.test;
import com.lrm.domain.User;
import com.lrm.domain.UserExample;
import com.lrm.mapper.UserMapper;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;
import java.io.InputStream;
import java.util.List;
/**
* @author RuiMing Lin
* @date 2021-03-18 12:37
* @description
*/
public class UserTest {
SqlSessionFactory sqlSessionFactory = null;
SqlSession openSession = null;
@Before
public void init() throws Exception {
String resource = "mybatis-config.xml";
InputStream inputStream = Resources.getResourceAsStream(resource);
sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
openSession = sqlSessionFactory.openSession();
}
@Test
public void test1() {
UserMapper mapper = openSession.getMapper(UserMapper.class);
User user = mapper.selectByPrimaryKey(1);
System.out.println("user = " + user);
}
@Test
public void test2() {
UserMapper mapper = openSession.getMapper(UserMapper.class);
UserExample example = new UserExample();
UserExample.Criteria criteria = example.createCriteria();
criteria.andUserNameLike("%小%");
criteria.andAddressLike("%广东%");
List<User> users = mapper.selectByExample(example);
System.out.println("users = " + users);
}
@Test
public void test3() {
UserMapper mapper = openSession.getMapper(UserMapper.class);
UserExample example = new UserExample();
long count = mapper.countByExample(example);
System.out.println("count = " + count);
}
@After
public void destroy() {
openSession.close();
}
}