Mybatis 逆向工程入门
Mybatis 逆向工程入门
一、导入 POM 文件
<?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>com.ktf</groupId>
<artifactId>mybatis-generator</artifactId>
<version>1.0-SNAPSHOT</version>
<dependencies>
<!-- Mybatis -->
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis</artifactId>
<version>3.5.6</version>
</dependency>
<!-- mysql驱动 -->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>8.0.21</version>
</dependency>
<!-- 日志处理 -->
<dependency>
<groupId>log4j</groupId>
<artifactId>log4j</artifactId>
<version>1.2.17</version>
</dependency>
<!-- 逆向工程 -->
<dependency>
<groupId>org.mybatis.generator</groupId>
<artifactId>mybatis-generator-core</artifactId>
<version>1.4.0</version>
</dependency>
<!-- 单元测试-->
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.13.1</version>
<scope>test</scope>
</dependency>
</dependencies>
</project>
二、编写 generatorConfig.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>
<!--加载外部的properties文件-->
<properties resource="jdbc.properties"/>
<!--targetRuntime="MyBatis3Simple"表示生成简易版本，这里创建原始版本,参数为MyBatis3-->
<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="false" />
</commentGenerator>
<!--数据库连接的信息：驱动类、连接地址、用户名、密码 -->
<jdbcConnection driverClass="${jdbc.driver}"
connectionURL="${jdbc.url}"
userId="${jdbc.username}"
password="${jdbc.password}">
</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:POJO类生成的位置 -->
<javaModelGenerator targetPackage="com.ktf.pojo" 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="com.ktf.mapper" 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.ktf.mapper" targetProject="./src/main/java">
<!-- enableSubPackages:是否让schema作为包的后缀 -->
<property name="enableSubPackages" value="false" />
</javaClientGenerator>
<!-- 指定生成哪些数据库表，要和数据库中对应，不能写错了，这里以t_user表为例，可以写多个；domainObjectName是要生成的实体类名称-->
<table schema="mybatis" tableName="t_user"/>
<table schema="mybatis" tableName="t_role"/>
<!-- 有些表的字段需要指定java类型
<table schema="" tableName="">
<columnOverride column="" javaType="" />
</table> -->
</context>
</generatorConfiguration>
三、编写 GeneratorSql 核心类
package com.ktf.generator;
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;
/**
* 逆向工程核心生成代码
*/
public class GeneratorSql {
public void generator() throws Exception {
List<String> warnings = new ArrayList<>();
boolean overwrite = true;
// 指定逆向工程配置文件
String file = GeneratorSql.class.getResource("/generatorConfig.xml").getFile();
File configFile = new File(file);
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);
}
// 执行main方法以生成代码
public static void main(String[] args) {
try {
GeneratorSql generatorSql = new GeneratorSql();
generatorSql.generator();
} catch (Exception e) {
e.printStackTrace();
}
}
}
四、编写log4j.properties
# Set root category priority to INFO and its only appender to CONSOLE.
#log4j.rootCategory=INFO, CONSOLE debug info warn error fatal
log4j.rootCategory=debug, CONSOLE
# CONSOLE is set to be a ConsoleAppender using a PatternLayout.
log4j.appender.CONSOLE=org.apache.log4j.ConsoleAppender
log4j.appender.CONSOLE.layout=org.apache.log4j.PatternLayout
log4j.appender.CONSOLE.layout.ConversionPattern=%d{ISO8601} %-6r [%15.15t] %-5p %30.30c %x - %m\n
五、编写 jdbc.properties
jdbc.driver=com.mysql.cj.jdbc.Driver
jdbc.url=jdbc:mysql:///mybatis?useUnicode=true&characterEncoding=utf8&serverTimezone=GMT
jdbc.username=root
jdbc.password=root
六、编写 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>
<!--加载外部的properties文件-->
<properties resource="jdbc.properties"/>
<!--给实体类的全限定类名给别名-->
<typeAliases>
<!--给单独的实体起别名-->
<!-- <typeAlias type="com.lagou.pojo.User" alias="user"></typeAlias>-->
<!--批量起别名：该包下所有的类的本身的类名：别名还不区分大小写-->
<package name="com.ktf.pojo"/>
</typeAliases>
<!--environments:运行环境-->
<environments default="development">
<environment id="development">
<!--当前事务交由JDBC进行管理-->
<transactionManager type="JDBC"/>
<!--当前使用mybatis提供的连接池-->
<dataSource type="POOLED">
<property name="driver" value="${jdbc.driver}"/>
<property name="url" value="${jdbc.url}"/>
<property name="username" value="${jdbc.username}"/>
<property name="password" value="${jdbc.password}"/>
</dataSource>
</environment>
</environments>
<!--引入映射配置文件-->
<mappers>
<package name="com.ktf.mapper"/>
</mappers>
</configuration>
七、数据库导入表
/*
Navicat Premium Data Transfer
Source Server : localhost
Source Server Type : MySQL
Source Server Version : 80020
Source Host : localhost:3306
Source Schema : mybatis
Target Server Type : MySQL
Target Server Version : 80020
File Encoding : 65001
Date: 12/06/2022 12:07:24
*/
SET NAMES utf8mb4;
SET FOREIGN_KEY_CHECKS = 0;
-- ----------------------------
-- Table structure for t_role
-- ----------------------------
DROP TABLE IF EXISTS `t_role`;
CREATE TABLE `t_role` (
`id` int(0) NOT NULL AUTO_INCREMENT,
`rolename` varchar(255) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL,
PRIMARY KEY (`id`) USING BTREE
) ENGINE = InnoDB CHARACTER SET = utf8 COLLATE = utf8_general_ci ROW_FORMAT = Dynamic;
-- ----------------------------
-- Records of t_role
-- ----------------------------
-- ----------------------------
-- Table structure for t_user
-- ----------------------------
DROP TABLE IF EXISTS `t_user`;
CREATE TABLE `t_user` (
`id` int(0) NOT NULL AUTO_INCREMENT,
`username` varchar(255) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL,
`password` varchar(255) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL,
`age` int(0) NULL DEFAULT NULL,
`address` varchar(255) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL,
PRIMARY KEY (`id`) USING BTREE
) ENGINE = InnoDB CHARACTER SET = utf8 COLLATE = utf8_general_ci ROW_FORMAT = Dynamic;
-- ----------------------------
-- Records of t_user
-- ----------------------------
INSERT INTO `t_user` VALUES (2, '张三', '123', 14, '深圳');
INSERT INTO `t_user` VALUES (3, '李四', '234', 20, '北京');
SET FOREIGN_KEY_CHECKS = 1;
八、运行 GeneratorSql
运行该类之后就会生成下列文件：
主要就是实体类、Mapper接口、Mapper映射文件，实体类中含有Example 的就是带条件进行CRUD的时候需要使用到的，下面会详解。
九、测试
不带条件的测试：
package com.ktf;
import com.ktf.mapper.TUserMapper;
import com.ktf.pojo.TUser;
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.IOException;
import java.io.InputStream;
import java.util.List;
//Mybatis的测试
public class MybatisTest {
//定义 SqlSession
private SqlSession sqlSession = null;
//定义 TUserMapper对象
private TUserMapper mapper = null;
@Before//在测试方法执行之前执行
public void getSqlSession(){
//1、加载 mybatis 全局配置文件
InputStream is = MybatisTest.class.getClassLoader().getResourceAsStream("mybatis-config.xml");
//2、创建SqlSessionFactory对象
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(is);
//3、根据 sqlSessionFactory 产生session
sqlSession = sqlSessionFactory.openSession();
//4、创建Mapper接口的的代理对象，getMapper方法底层会通过动态代理生成TUserMapper的代理实现类
mapper = sqlSession.getMapper(TUserMapper.class);
}
@After//在测试方法执行完成之后执行
public void destroy() throws IOException {
sqlSession.commit();
sqlSession.close();
}
//查询所有用户信息
@Test
public void selectAllUser(){
// 传入null表示查询所有
List<TUser> tUsers = mapper.selectByExample(null);
for (TUser tUser : tUsers) {
System.out.println(tUser.toString());
}
}
//根据用户id查询用户
@Test
public void selectByUserId(){
TUser tUser = mapper.selectByPrimaryKey(1);
System.out.println(tUser);
}
//添加用户信息
@Test
public void insertUser(){
TUser tUser = new TUser();
// tUser.setId(3);
tUser.setUsername("王五");
tUser.setPassword("234");
tUser.setAge(20);
tUser.setAddress("上海");
int i = mapper.insertSelective(tUser);
System.out.println(i>0?"添加成功":"添加失败");
}
//更新用户信息
@Test
public void updateUser(){
TUser tUser = new TUser();
//这里要设置id才能修改成功，否则不知道修改哪一条数据
tUser.setId(2);
tUser.setAge(14);
tUser.setAddress("深圳");
int i = mapper.updateByPrimaryKeySelective(tUser);
System.out.println(i>0?"修改成功":"修改失败");
}
//删除用户信息
@Test
public void deleteUser(){
int i = mapper.deleteByPrimaryKey(3);
System.out.println(i>0?"删除成功":"删除失败");
}
}
带条件的测试：
package com.ktf;
import com.ktf.mapper.TUserMapper;
import com.ktf.pojo.TUser;
import com.ktf.pojo.TUserExample;
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.IOException;
import java.io.InputStream;
import java.util.List;
// Mybatis的测试
public class MybatisTest1 {
//定义 SqlSession
private SqlSession sqlSession = null;
//定义 UserMapper对象
private TUserMapper mapper = null;
@Before//在测试方法执行之前执行
public void getSqlSession(){
//1、加载 mybatis 全局配置文件
InputStream is = MybatisTest1.class.getClassLoader().getResourceAsStream("mybatis-config.xml");
//2、创建SqlSessionFactory对象
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(is);
//3、根据 sqlSessionFactory 产生session
sqlSession = sqlSessionFactory.openSession();
//4、创建Mapper接口的的代理对象，getMapper方法底层会通过动态代理生成UserMapper的代理实现类
mapper = sqlSession.getMapper(TUserMapper.class);
}
@After//在测试方法执行完成之后执行
public void destroy() throws IOException {
sqlSession.commit();
sqlSession.close();
}
//模糊查询用户信息
@Test
public void selectUserLike(){
TUserExample example = new TUserExample();
TUserExample.Criteria criteria = example.createCriteria();
//模糊条件
criteria.andUsernameLike("%张%");
// sql语句相当于：select * from t_user WHERE ( username like ? )
List<TUser> tUsers = mapper.selectByExample(example);
for (TUser tUser : tUsers) {
System.out.println(tUser);
}
}
//查询年龄在18-30岁之间的用户信息
@Test
public void selectUserBetween(){
TUserExample example = new TUserExample();
TUserExample.Criteria criteria = example.createCriteria();
//Between条件
criteria.andAgeBetween(13,19);
example.or(criteria);
example.setDistinct(true);
List<TUser> tUsers = mapper.selectByExample(example);
for (TUser tUser : tUsers) {
System.out.println(tUser);
}
}
//查询用户名A或B
@Test
public void selectUserOr(){
TUserExample example = new TUserExample();
TUserExample.Criteria criteria1 = example.createCriteria();
criteria1.andUsernameEqualTo("张三");
TUserExample.Criteria criteria2 = example.createCriteria();
criteria2.andUsernameEqualTo("王五");
//将criteria2条件拼接在 or 关键字字后面
example.or(criteria2);
// sql语句相当于：select * from t_user WHERE ( username = ? ) or( username = ? )
List<TUser> tUsers = mapper.selectByExample(example);
for (TUser tUser : tUsers) {
System.out.println(tUser);
}
}
//根据用户名删除用户
@Test
public void deleteUserExample(){
TUserExample example = new TUserExample();
TUserExample.Criteria criteria = example.createCriteria();
criteria.andUsernameEqualTo("张五");
// sql语句相当于：delete from t_user WHERE ( name = ? )
int i = mapper.deleteByExample(example);
System.out.println(i>0?"删除成功":"删除失败");
}
}
逆向工程生成的条件查询中含有很多条件可以设置，看需求使用哪些。
