逆向工程
1. 首先我们需要知道什么是逆向工程
mybatis逆向工程简称MBG。它是专门为MyBatis框架使用者定制的代码生成器。
可以快速的根据表生成对应的映射文件，接口，以及Bean类对象。
逆向工程只能对单表生成CRUD操作
它可以帮我们对比数据库表之后，生成大量的这个基础代码。
这些基础代码有：
1、数据库表对应的javaBean对象
2、这些javaBean对象对应的Mapper接口
3、这些Mapper接口对应的配置文件
<!-- 去掉全部的注释 -->
<commentGenerator>
<property name="suppressAllComments" value="true" />
</commentGenerator>
准备数据库表
create database mbg;
use mbg;
create table t_user(
`id` int primary key auto_increment, /*主键自增*/
`username` varchar(30) not null unique,/*用户名非空且唯一*/
`password` varchar(40) not null,/*密码非空*/
`email` varchar(50)/*邮箱*/
);
insert into t_user(`username`,`password`,`email`) values('admin','admin','[email protected]');
insert into t_user(`username`,`password`,`email`) values('wzg168','123456','[email protected]');
create table t_book(
`id` int primary key auto_increment,
`name` varchar(50),
`author` varchar(50),
`price` decimal(11,2),
`sales` int,
`stock` int
);
## 插入初始化测试数据
insert into t_book(`id` , `name` , `author` , `price` , `sales` , `stock` )
values(null , '3天精通java' , '菜丸' , 55 ,555 , 5);
insert into t_book(`id` , `name` , `author` , `price` , `sales` , `stock` )
values(null , 'JVM底层原理' , '菜丸' , 66 , 666 , 6);
insert into t_book(`id` , `name` , `author` , `price` , `sales` , `stock` )
values(null , '数据结构' , '菜丸' , 77, 777 , 7);
select * from t_user;
select * from t_book;
逆向工程配置文件
<?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="DB2Tables" targetRuntime="MyBatis3">
<!-- 去掉全部的注释 -->
<commentGenerator>
<property name="suppressAllComments" value="true" />
</commentGenerator>
<!-- 修改 数据库的 连接属性 -->
<jdbcConnection driverClass="com.mysql.jdbc.Driver"
connectionURL="jdbc:mysql://localhost:3306/mbg"
userId="root"
password="root">
</jdbcConnection>
<javaTypeResolver >
<property name="forceBigDecimals" value="false" />
</javaTypeResolver>
<!--配置生成javaBean的
targetPackage javaBean的包名
targetProject 生成在哪个项目目录下
-->
<javaModelGenerator targetPackage="com.caiwan.pojo" targetProject=".\mybatis-mbg\src">
<property name="enableSubPackages" value="true" />
<property name="trimStrings" value="true" />
</javaModelGenerator>
<!--
配置生成的Mapper.xml配置文件
targetPackage javaBean的包名
targetProject 生成在哪个项目目录下
-->
<sqlMapGenerator targetPackage="com.caiwan.mapper" targetProject=".\mybatis-mbg\src">
<property name="enableSubPackages" value="true" />
</sqlMapGenerator>
<!-- 配置生成Mapper接口 -->
<javaClientGenerator type="XMLMAPPER" targetPackage="com.caiwan.mapper"
targetProject=".\mybatis-mbg\src">
<property name="enableSubPackages" value="true" />
</javaClientGenerator>
<!--
数据库一个表对应一个table标签
tableName是表名
domainObjectName 设置生成的类名
-->
<table tableName="t_user" domainObjectName="User" />
<table tableName="t_book" domainObjectName="Book" />
</context>
</generatorConfiguration>
执行逆向工程的代码:
package com.caiwan.mbg.runner;
import org.mybatis.generator.api.MyBatisGenerator;
import org.mybatis.generator.config.Configuration;
import org.mybatis.generator.config.xml.ConfigurationParser;
import org.mybatis.generator.exception.InvalidConfigurationException;
import org.mybatis.generator.exception.XMLParserException;
import org.mybatis.generator.internal.DefaultShellCallback;
import java.io.File;
import java.io.IOException;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;
public class MbgRunner {
public static void main(String[] args) throws IOException, XMLParserException, InvalidConfigurationException, SQLException, InterruptedException {
List<String> warnings = new ArrayList<String>();
boolean overwrite = true;
File configFile = new File("mybatis-mbg/mbg.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);
}
}
生成测试代码：
package com.caiwan.test;
import com.caiwan.mapper.BookMapper;
import com.caiwan.pojo.Book;
import com.caiwan.pojo.BookExample;
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.BeforeClass;
import org.junit.Test;
import java.io.IOException;
import java.math.BigDecimal;
import java.util.List;
public class BookMapperTest {
static SqlSessionFactory sqlSessionFactory;
// @BeforeClass在当前类的所有测试方法之前执行。注解在【静态方法】上。
@BeforeClass
public static void init() throws IOException {
sqlSessionFactory= new SqlSessionFactoryBuilder().build(Resources.getResourceAsStream("mybatis-config.xml"));
}
@Test
public void countByExample() {
SqlSession session = sqlSessionFactory.openSession();
try {
BookMapper mapper = session.getMapper(BookMapper.class);
// 创建一个条件类
BookExample bookExample = new BookExample();
// 创建一个查询条件
BookExample.Criteria criteria = bookExample.createCriteria();
// where xxx = xxx and xxx = xxx;
// where xxx = xxx or xxx = xxx;
// 查询价格大于16的图书有几条记录
// criteria.andPriceGreaterThan(new BigDecimal(16));
// 查询销量大于10 , 且 库存 大于50的记录
// criteria.andSalesGreaterThan(10);
// criteria.andStockGreaterThan(50);
// 查询销量大于10 , 或 库存 大于50的记录
criteria.andSalesEqualTo(10);
bookExample.or().andStockGreaterThan(50);
// count() 用于查询数量的方法
// count 用于查询数量的
// ByExample按条件来查询
int i = mapper.countByExample(bookExample);
System.out.println(i);
} finally {
session.close();
}
}
@Test
public void deleteByExample() {
SqlSession session = sqlSessionFactory.openSession();
try {
BookMapper mapper = session.getMapper(BookMapper.class);
// mapper.deleteByExample(null);// 只要条件是空,就是全表操作
BookExample bookExample = new BookExample();
bookExample.createCriteria().andSalesGreaterThan(10000);
mapper.deleteByExample(bookExample);
session.commit();
} finally {
session.close();
}
}
@Test
public void deleteByPrimaryKey() {
SqlSession session = sqlSessionFactory.openSession();
try {
BookMapper mapper = session.getMapper(BookMapper.class);
mapper.deleteByPrimaryKey(8);
session.commit();
} finally {
session.close();
}
}
@Test
public void insert() {
SqlSession session = sqlSessionFactory.openSession();
try {
BookMapper mapper = session.getMapper(BookMapper.class);
mapper.insert(new Book(null,"刷leetcode的一百道题", "菜丸1", new BigDecimal(1234), 1234,1234));
mapper.insert(new Book(null,"java从入门到放弃", "菜丸2", new BigDecimal(1234), 1234,1234));
session.commit();
} finally {
session.close();
}
}
@Test
public void insertSelective() {
SqlSession session = sqlSessionFactory.openSession();
try {
BookMapper mapper = session.getMapper(BookMapper.class);
Book book = new Book(null,"数据库", null,null,100,100);
// 方法末尾Selective就表示操作的时候,不带null值的列
// mapper.insertSelective(book);// null列不在操作范围内
mapper.insert(book);// null列一样在操作范围内
session.commit();
} finally {
session.close();
}
}
@Test
public void selectByExample() {
SqlSession session = sqlSessionFactory.openSession();
try {
BookMapper mapper = session.getMapper(BookMapper.class);
BookExample bookExample = new BookExample();
bookExample.createCriteria().andIdBetween(1,10);
// 设置排序字段
bookExample.setOrderByClause(" price desc ");
// List books = mapper.selectByExample(null);// 条件为null,就整表操作
List<Book> books = mapper.selectByExample(bookExample);// 有条件
books.forEach(System.out::println);
} finally {
session.close();
}
}
@Test
public void selectByPrimaryKey() {
SqlSession session = sqlSessionFactory.openSession();
try {
BookMapper mapper = session.getMapper(BookMapper.class);
Book book = mapper.selectByPrimaryKey(6);
System.out.println(book);
} finally {
session.close();
}
}
@Test
public void updateByExampleSelective() {
SqlSession session = sqlSessionFactory.openSession();
try {
BookMapper mapper = session.getMapper(BookMapper.class);
Book book = new Book(null,"忽略null的列", null, null,1234,124);
BookExample bookExample = new BookExample();
bookExample.createCriteria().andIdGreaterThan(8);
/**
* 根据条件来进行更新,而且不带null的列
*/
mapper.updateByExampleSelective(book,bookExample);
session.commit();
} finally {
session.close();
}
}
@Test
public void updateByExample() {
SqlSession session = sqlSessionFactory.openSession();
try {
BookMapper mapper = session.getMapper(BookMapper.class);
Book book = new Book(null,"忽略null的列", null, null,1234,124);
BookExample bookExample = new BookExample();
bookExample.createCriteria().andIdGreaterThan(8);
/**
* 根据条件来进行更新,而且不带null的列
*/
mapper.updateByExample(book,bookExample);
session.commit();
} finally {
session.close();
}
}
@Test
public void updateByPrimaryKeySelective() {
SqlSession session = sqlSessionFactory.openSession();
try {
BookMapper mapper = session.getMapper(BookMapper.class);
Book book = new Book(null,"忽略null的列", null, null,1234,124);
/**
* 根据条件来进行更新,而且不带null的列
*/
mapper.updateByPrimaryKeySelective(book);
session.commit();
} finally {
session.close();
}
}
@Test
public void updateByPrimaryKey() {
SqlSession session = sqlSessionFactory.openSession();
try {
BookMapper mapper = session.getMapper(BookMapper.class);
Book book = new Book(null,"忽略null的列", null, null,1234,124);
/**
* 根据条件来进行更新
*/
mapper.updateByPrimaryKey(book);
session.commit();
} finally {
session.close();
}
}
}
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