mybaits需要程序员自己编写sql语句,mybatis官方提供逆向工程,可以针对单表自动生成mybatis执行所需要的代码（mapper.java,mapper.xml、po..）
企业实际开发中，常用的逆向工程方式：由数据库的表生成java代码。
先附上官网链接：
下载逆向工程
这里其实可以添加Maven依赖的，因为跟着视频做的，所以我就建了个普通工程，直接添加了个lib文件夹，把要用的jar包直接copy进来了。
maven中央仓库
MyBatis-Generator下载地址：【MyBatis Generator Core】
使用方法
运行逆向工程
根据官网说的（Running MyBatis Generator）：
Running MyBatis Generator
MyBatis Generator (MBG) can be run in the following ways:
- From the command prompt with an XML configuration
- As an Ant task with an XML configuration
- As a Maven Plugin
- From another Java program with an XML configuration
- From another Java program with a Java based configuration
还可以通过eclipse的插件生成代码
建议使用java程序方式，不依赖开发工具。
生成代码配置文件
<?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://120.25.162.238:3306/mybatis001?characterEncoding=utf-8"
userId="root"
password="123">
</jdbcConnection>
<!-- <jdbcConnection driverClass="oracle.jdbc.OracleDriver"
connectionURL="jdbc:oracle:thin:@127.0.0.1:1521:yycg"
userId="yycg"
password="yycg">
</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.iot.ssm.po"
targetProject=".\src">
<!-- 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.iot.ssm.mapper"
targetProject=".\src">
<!-- 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.iot.ssm.mapper"
targetProject=".\src">
<!-- 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="items"></table>
<table tableName="orders"></table>
<table tableName="orderdetail"></table>
<table tableName="user"></table>
<!-- <table schema="" tableName="sys_user"></table>
<table schema="" tableName="sys_role"></table>
<table schema="" tableName="sys_permission"></table>
<table schema="" tableName="sys_user_role"></table>
<table schema="" tableName="sys_role_permission"></table> -->
<!-- 有些表的字段需要指定java类型
<table schema="" tableName="">
<columnOverride column="" javaType="" />
</table> -->
</context>
</generatorConfiguration>
需要注意的位置：
javaModelGenerator,生成PO类的位置sqlMapGenerator,mapper映射文件生成的位置javaClientGenerator,mapper接口生成的位置table,指定数据库表
执行生成程序
public void generator() throws Exception{
List<String> warnings = new ArrayList<String>();
boolean overwrite = true;
//指定逆向工程配置文件
File configFile = new File("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);
}
日志输出：
2016-02-27 16:29:46,419 [main] DEBUG [org.mybatis.generator.internal.db.DatabaseIntrospector] - Retrieving column information for table "items"
2016-02-27 16:29:46,477 [main] DEBUG [org.mybatis.generator.internal.db.DatabaseIntrospector] - Found column "id", data type 4, in table "mybatis001..items"
2016-02-27 16:29:46,477 [main] DEBUG [org.mybatis.generator.internal.db.DatabaseIntrospector] - Found column "name", data type 12, in table "mybatis001..items"
2016-02-27 16:29:46,477 [main] DEBUG [org.mybatis.generator.internal.db.DatabaseIntrospector] - Found column "price", data type 7, in table "mybatis001..items"
2016-02-27 16:29:46,477 [main] DEBUG [org.mybatis.generator.internal.db.DatabaseIntrospector] - Found column "detail", data type -1, in table "mybatis001..items"
2016-02-27 16:29:46,477 [main] DEBUG [org.mybatis.generator.internal.db.DatabaseIntrospector] - Found column "pic", data type 12, in table "mybatis001..items"
2016-02-27 16:29:46,478 [main] DEBUG [org.mybatis.generator.internal.db.DatabaseIntrospector] - Found column "createtime", data type 93, in table "mybatis001..items"
2016-02-27 16:29:46,503 [main] DEBUG [org.mybatis.generator.internal.db.DatabaseIntrospector] - Retrieving column information for table "orders"
2016-02-27 16:29:46,551 [main] DEBUG [org.mybatis.generator.internal.db.DatabaseIntrospector] - Found column "id", data type 4, in table "mybatis001..orders"
2016-02-27 16:29:46,551 [main] DEBUG [org.mybatis.generator.internal.db.DatabaseIntrospector] - Found column "user_id", data type 4, in table "mybatis001..orders"
2016-02-27 16:29:46,551 [main] DEBUG [org.mybatis.generator.internal.db.DatabaseIntrospector] - Found column "number", data type 12, in table "mybatis001..orders"
2016-02-27 16:29:46,551 [main] DEBUG [org.mybatis.generator.internal.db.DatabaseIntrospector] - Found column "createtime", data type 93, in table "mybatis001..orders"
2016-02-27 16:29:46,551 [main] DEBUG [org.mybatis.generator.internal.db.DatabaseIntrospector] - Found column "note", data type 12, in table "mybatis001..orders"
2016-02-27 16:29:46,577 [main] DEBUG [org.mybatis.generator.internal.db.DatabaseIntrospector] - Retrieving column information for table "orderdetail"
2016-02-27 16:29:46,630 [main] DEBUG [org.mybatis.generator.internal.db.DatabaseIntrospector] - Found column "id", data type 4, in table "mybatis001..orderdetail"
2016-02-27 16:29:46,630 [main] DEBUG [org.mybatis.generator.internal.db.DatabaseIntrospector] - Found column "orders_id", data type 4, in table "mybatis001..orderdetail"
2016-02-27 16:29:46,631 [main] DEBUG [org.mybatis.generator.internal.db.DatabaseIntrospector] - Found column "items_id", data type 4, in table "mybatis001..orderdetail"
2016-02-27 16:29:46,631 [main] DEBUG [org.mybatis.generator.internal.db.DatabaseIntrospector] - Found column "items_num", data type 4, in table "mybatis001..orderdetail"
2016-02-27 16:29:46,656 [main] DEBUG [org.mybatis.generator.internal.db.DatabaseIntrospector] - Retrieving column information for table "user"
2016-02-27 16:29:46,706 [main] DEBUG [org.mybatis.generator.internal.db.DatabaseIntrospector] - Found column "id", data type 4, in table "mybatis001..user"
2016-02-27 16:29:46,706 [main] DEBUG [org.mybatis.generator.internal.db.DatabaseIntrospector] - Found column "username", data type 12, in table "mybatis001..user"
2016-02-27 16:29:46,706 [main] DEBUG [org.mybatis.generator.internal.db.DatabaseIntrospector] - Found column "birthday", data type 91, in table "mybatis001..user"
2016-02-27 16:29:46,706 [main] DEBUG [org.mybatis.generator.internal.db.DatabaseIntrospector] - Found column "sex", data type 1, in table "mybatis001..user"
2016-02-27 16:29:46,706 [main] DEBUG [org.mybatis.generator.internal.db.DatabaseIntrospector] - Found column "address", data type 12, in table "mybatis001..user"
生成后的代码：
使用生成的代码
需要将生成工程中所生成的代码拷贝到自己的工程中。
测试ItemsMapper中的方法
package com.iot.ssm.mapper;
import static org.junit.Assert.*;
import java.util.Date;
import java.util.List;
import com.iot.ssm.po.Items;
import com.iot.ssm.po.ItemsExample;
import org.junit.Before;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class ItemsMapperTest {
private ApplicationContext applicationContext;
private ItemsMapper itemsMapper;
//在setUp这个方法得到spring容器
@Before
public void setUp() throws Exception {
applicationContext = new ClassPathXmlApplicationContext("classpath:spring/applicationContext.xml");
itemsMapper = (ItemsMapper) applicationContext.getBean("itemsMapper");
}
//根据主键删除
@Test
public void testDeleteByPrimaryKey() {
}
//插入
@Test
public void testInsert() {
//构造 items对象
Items items = new Items();
items.setName("手机");
items.setPrice(999f);
items.setCreatetime(new Date());
itemsMapper.insert(items);
}
//自定义条件查询
@Test
public void testSelectByExample() {
ItemsExample itemsExample = new ItemsExample();
//通过criteria构造查询条件
ItemsExample.Criteria criteria = itemsExample.createCriteria();
criteria.andNameEqualTo("笔记本");
//可能返回多条记录
List<Items> list = itemsMapper.selectByExample(itemsExample);
System.out.println(list);
}
//根据主键查询
@Test
public void testSelectByPrimaryKey() {
Items items = itemsMapper.selectByPrimaryKey(1);
System.out.println(items);
}
//更新数据
@Test
public void testUpdateByPrimaryKey() {
//对所有字段进行更新，需要先查询出来再更新
Items items = itemsMapper.selectByPrimaryKey(1);
items.setName("手机");
itemsMapper.updateByPrimaryKey(items);
//如果传入字段不空为才更新，在批量更新中使用此方法，不需要先查询再更新
//itemsMapper.updateByPrimaryKeySelective(record);
}
}
