Mybatis 29_枚举类型处理器的三种应用方式 项目0401EnumTypeHandler，0403EnumOrdinalTypeHandler ，0403枚举变态处理

枚举类型的类型处理器

MyBatis为提供了如下枚举类型处理器：

－ EnumTypeHandler：该处理器将枚举值转换成对应的名称（字符串），这是默认的。
如果使用这种方式，程序不需要任何额外的配置。
项目0401EnumTypeHandler
－ EnumOrdinalTypeHandler：该处理器将枚举值转换成对应的序号（整数）。
需要配置（不需要修改XML Mapper文件，只要修改 mybatis-config.xml配置文件即可）。
项目0402EnumOrdinalTypeHandler
▲ 同一个枚举类型，有个地方要保存枚举名称，有的要保存枚举序号：
项目0403枚举变态处理

指定类型处理器有两种方式：

1. 全局式：在config.xml文件中通过进行配置。

 <typeHandlers>
 	
 	<typeHandler handler="org.apache.ibatis.type.EnumOrdinalTypeHandler"
 		javaType="org.itcheng.app.domain.Season"
 		jdbcType="INTEGER"/>
 typeHandlers>	

2. 局部式：在XML Mappper文件中配置，
   在#{}和中通过typeHandler属性为单个参数、数据列指定局部类型处理器。

	<insert id="saveNews">
		insert into news_inf values (null, #{title}, #{content}, 
		#{happenSeason, typeHandler=org.apache.ibatis.type.EnumOrdinalTypeHandler,
		javaType=org.itcheng.app.domain.Season}, #{recordSeason})
	insert>
	
	<select id="findNews" resultMap="newsMap">
		select news_id id, news_title title, news_content content, 
		happen_season happenSeason, record_season recordSeason
		from news_inf where news_id > #{id}		
	select>
	
	<resultMap type="news" id="newsMap">
		
		<result column="id" property="id"/>
		<result column="happenSeason" property="happenSeason" 
			typeHandler="org.apache.ibatis.type.EnumOrdinalTypeHandler"
			javaType="org.itcheng.app.domain.Season"/>
	resultMap>

项目0401EnumTypeHandler

主类

package lee;

import java.io.IOException;
import java.io.InputStream;
import java.util.List;

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.itcheng.app.dao.NewsMapper;
import org.itcheng.app.domain.News;
import org.itcheng.app.domain.Season;

public class NewsManager
{
	// SqlSessionFactory应该是应用级别
	private static SqlSessionFactory sqlSessionFactory;
	
	public static void main(String[] args) throws IOException
	{
		String resource = "mybatis-config.xml";
		InputStream inputStream = Resources.getResourceAsStream(resource);
		// 1. 创建SqlSessionFactory
		sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
		// 2. 打开SqlSession
		SqlSession sqlSession = sqlSessionFactory.openSession();
		//EnumTypeHandler
		// 保存消息
		saveNews(sqlSession);
		
		// 更新消息
//		updateNews(sqlSession);		
		
		// 删除消息
//		deleteNews(sqlSession);			
		
		// 查询消息
//		selectNews(sqlSession);				
	}
	
	public static void saveNews(SqlSession sqlSession)
	{
		News news = new News(null, "测试标题", "测试内容");
		news.setHappenSeason(Season.SUMMER);
		
		NewsMapper newsMapper = sqlSession.getMapper(NewsMapper.class);
		
		newsMapper.saveNews(news);
		
		// 4. 提交事务
		sqlSession.commit();
		// 5. 关闭资源
		sqlSession.close();	
	}
	
	public static void updateNews(SqlSession sqlSession)
	{

		News news = new News(1, "修改的标题", "修改的内容");
		news.setHappenSeason(Season.FALL);
		
		NewsMapper newsMapper = sqlSession.getMapper(NewsMapper.class);
		
		newsMapper.updateNews(news);
		
		// 4. 提交事务
		sqlSession.commit();
		// 5. 关闭资源
		sqlSession.close();	
	
	}
	
	public static void deleteNews(SqlSession sqlSession)
	{
		// SqlSession的insert、update、delete方法都只是去执行DML语句
		// 因此这个三个方法并没有本质的区别：它们都只是调用PreparedStatement的executeUpdate()方法来执行DML语句。
		
		NewsMapper newsMapper = sqlSession.getMapper(NewsMapper.class);
		newsMapper.deleteNews(2);
		
		// 4. 提交事务
		sqlSession.commit();
		// 5. 关闭资源
		sqlSession.close();	
	}
	
	public static void selectNews(SqlSession sqlSession)
	{
		// 此处的NewsMapper只是一个接口
		// MyBatis会使用JDK的动态代理为Mapper接口生成实现类
		NewsMapper newsMapper = sqlSession.getMapper(NewsMapper.class);
		System.out.println(newsMapper.getClass());
		List<?> list = newsMapper.findNews(-1);
		
		System.out.println(list);
		
		// 4. 提交事务
		sqlSession.commit();
		// 5. 关闭资源
		sqlSession.close();	
	}	
}

映射文件

DOCTYPE mapper
	PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
	"http://mybatis.org/dtd/mybatis-3-mapper.dtd">
	
<mapper namespace="org.itcheng.app.dao.NewsMapper">
	
	<insert id="saveNews">
		insert into news_inf values (null, #{title}, #{content}, #{happenSeason})
	insert>
	
	
	<update id="updateNews">
		update news_inf set news_title = #{title}, news_content = #{content},
		happen_season=#{happenSeason}
		where news_id=#{id}
	update>
	
	
	<delete id="deleteNews">
		delete from news_inf where news_id = #{xyz} 
	delete>
	
	
	<select id="findNews" resultType="news">
		select news_id id, news_title title, news_content content 
		happen_season happenSeason
		from news_inf where news_id > #{id}		
	select>
	
mapper>

用户类

package org.itcheng.app.domain;

// 默认的别名是news
public class News
{
	private Integer id;
	private String title;
	private String content;
	// 它是一个枚举类型的属性
	private Season happenSeason;//消息实在哪个季节发生的，数据库存字符串
	
	//添加set和get方法，有参无参构造器
}

自定义枚举类

package org.itcheng.app.domain;

public enum Season
{
	SPRING, SUMMER, FALL, WINTER;
}

表结构

create table news_inf
(
 news_id int primary key auto_increment,
 news_title varchar(255),
 news_content varchar(255),
 happen_season varchar(255)
);

项目0402EnumOrdinalTypeHandler

主类

package lee;

import java.io.IOException;
import java.io.InputStream;
import java.util.List;

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.itcheng.app.dao.NewsMapper;
import org.itcheng.app.domain.News;
import org.itcheng.app.domain.Season;

public class NewsManager
{
	// SqlSessionFactory应该是应用级别
	private static SqlSessionFactory sqlSessionFactory;
	
	public static void main(String[] args) throws IOException
	{
		String resource = "mybatis-config.xml";
		InputStream inputStream = Resources.getResourceAsStream(resource);
		// 1. 创建SqlSessionFactory
		sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
		// 2. 打开SqlSession
		SqlSession sqlSession = sqlSessionFactory.openSession();
		
		// 保存消息
//		saveNews(sqlSession);
		
		// 更新消息
//		updateNews(sqlSession);		
		
		// 删除消息
//		deleteNews(sqlSession);			
		
		// 查询消息
		selectNews(sqlSession);				
	}
	
	public static void saveNews(SqlSession sqlSession)
	{
		News news = new News(null, "测试标题", "测试内容");
		news.setHappenSeason(Season.SUMMER);
		
		NewsMapper newsMapper = sqlSession.getMapper(NewsMapper.class);
		
		newsMapper.saveNews(news);
		
		// 4. 提交事务
		sqlSession.commit();
		// 5. 关闭资源
		sqlSession.close();	
	}
	
	public static void updateNews(SqlSession sqlSession)
	{

		News news = new News(1, "修改的标题", "修改的内容");
		news.setHappenSeason(Season.FALL);
		
		NewsMapper newsMapper = sqlSession.getMapper(NewsMapper.class);
		
		newsMapper.updateNews(news);
		
		// 4. 提交事务
		sqlSession.commit();
		// 5. 关闭资源
		sqlSession.close();	
	
	}
	
	public static void deleteNews(SqlSession sqlSession)
	{
		
		// SqlSession的insert、update、delete方法都只是去执行DML语句
		// 因此这个三个方法并没有本质的区别：它们都只是调用PreparedStatement的executeUpdate()方法来执行DML语句。
		
		NewsMapper newsMapper = sqlSession.getMapper(NewsMapper.class);
		newsMapper.deleteNews(2);
		
		// 4. 提交事务
		sqlSession.commit();
		// 5. 关闭资源
		sqlSession.close();	
	}
	
	public static void selectNews(SqlSession sqlSession)
	{
		// 此处的NewsMapper只是一个接口
		// MyBatis会使用JDK的动态代理为Mapper接口生成实现类
		NewsMapper newsMapper = sqlSession.getMapper(NewsMapper.class);
		System.out.println(newsMapper.getClass());
		List<?> list = newsMapper.findNews(-1);
		list.forEach(e -> {
			System.out.println(((News) e).getHappenSeason());
		});
		
		System.out.println(list);
		
		// 4. 提交事务
		sqlSession.commit();
		// 5. 关闭资源
		sqlSession.close();	
		/*结果如下
		 * class com.sun.proxy.$Proxy17
		 * DEBUG [main] org.itcheng.app.dao.NewsMapper.findNews ==>  Preparing: select news_id id, news_title title, news_content content, happen_season happenSeason from news_inf where news_id > ? 
		 * DEBUG [main] org.itcheng.app.dao.NewsMapper.findNews ==> Parameters: -1(Integer)
		 * DEBUG [main] org.itcheng.app.dao.NewsMapper.findNews <==      Total: 3（结果集条目数）
		 * SUMMER
		 * SUMMER
		 * SUMMER
		 * [org.itcheng.app.domain.News@5536379e, org.itcheng.app.domain.News@277f7dd3, org.itcheng.app.domain.News@6c8bca63]
		 * */
	}		
}

主配置文件

DOCTYPE configuration
	PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
	"http://mybatis.org/dtd/mybatis-3-config.dtd">
	
<configuration>

 	<typeAliases>
 		
 		<package name="org.itcheng.app.domain"/>
 	typeAliases>
 	
 	<typeHandlers>
		
		<typeHandler handler="org.apache.ibatis.type.EnumOrdinalTypeHandler"
			javaType="org.itcheng.app.domain.Season"
			jdbcType="INTEGER"/>
	typeHandlers>	
 	
	
	<environments default="mysql">
		
		<environment id="mysql">
			
			<transactionManager type="JDBC" />
			
			<dataSource type="POOLED">
				<property name="driver" value="com.mysql.jdbc.Driver" />
				<property name="url" value="jdbc:mysql://localhost:3306/mybatis?serverTimezone=UTC" />
				<property name="username" value="root" />
				<property name="password" value="root" />
			dataSource>
		environment>
	environments>
	<mappers>
		
		<mapper resource="org/itcheng/app/dao/NewsMapper.xml" />
	mappers>
configuration>

映射文件

DOCTYPE mapper
	PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
	"http://mybatis.org/dtd/mybatis-3-mapper.dtd">
	
<mapper namespace="org.itcheng.app.dao.NewsMapper">
	
	<insert id="saveNews">
		insert into news_inf values (null, #{title}, #{content}, #{happenSeason})
	insert>
	
	
	<update id="updateNews">
		update news_inf set news_title = #{title}, news_content = #{content},
		happen_season=#{happenSeason}
		where news_id=#{id}
	update>
	
	
	<delete id="deleteNews">
		delete from news_inf where news_id = #{xyz} 
	delete>
	
	<select id="findNews" resultType="news">
		select news_id id, news_title title, news_content content, 
		happen_season happenSeason
		from news_inf where news_id > #{id}		
	select>
	
mapper>

用户类

package org.itcheng.app.domain;

// 默认的别名是news
public class News
{
	private Integer id;
	private String title;
	private String content;
	// 它是一个枚举类型的属性（程序要求happenSeason保存枚举的序号值）
	private Season happenSeason;//数据库 类型为integer
	
	//添加set和get方法，有参无参构造器
}

自定义枚举类

package org.itcheng.app.domain;

public enum Season
{
	SPRING, SUMMER, FALL, WINTER;
}

表结构

create table news_inf
(
 news_id int primary key auto_increment,
 news_title varchar(255),
 news_content varchar(255),
 happen_season integer
);

项目0403枚举变态处理

主类

package lee;

import java.io.IOException;
import java.io.InputStream;
import java.util.List;

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.itcheng.app.dao.NewsMapper;
import org.itcheng.app.domain.News;
import org.itcheng.app.domain.Season;

public class NewsManager
{
	// SqlSessionFactory应该是应用级别
	private static SqlSessionFactory sqlSessionFactory;
	
	public static void main(String[] args) throws IOException
	{
		String resource = "mybatis-config.xml";
		InputStream inputStream = Resources.getResourceAsStream(resource);
		// 1. 创建SqlSessionFactory
		sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
		// 2. 打开SqlSession
		SqlSession sqlSession = sqlSessionFactory.openSession();
		
		// 保存消息
//		saveNews(sqlSession);
		
		// 更新消息
		updateNews(sqlSession);	
			
		// 查询消息
//		selectNews(sqlSession);		
	}
	
	public static void saveNews(SqlSession sqlSession)
	{
		News news = new News(null, "测试标题", "测试内容");
		news.setHappenSeason(Season.SUMMER);
		news.setRecordSeason(Season.FALL);
		
		NewsMapper newsMapper = sqlSession.getMapper(NewsMapper.class);
		
		newsMapper.saveNews(news);
		
		// 4. 提交事务
		sqlSession.commit();
		// 5. 关闭资源
		sqlSession.close();	
		/*
		 * DEBUG [main] org.itcheng.app.dao.NewsMapper.saveNews ==>  Preparing: insert into news_inf values (null, ?, ?, ?, ?) 
		 * DEBUG [main] org.itcheng.app.dao.NewsMapper.saveNews ==> Parameters: 测试标题(String), 测试内容(String), 1(Integer), FALL(String)
		 * DEBUG [main] org.itcheng.app.dao.NewsMapper.saveNews <==    Updates: 1
		 * */
	}
	
	public static void updateNews(SqlSession sqlSession)
	{

		News news = new News(1, "修改的标题3", "修改的内容");
		news.setHappenSeason(Season.FALL);
		news.setRecordSeason(Season.FALL);
		NewsMapper newsMapper = sqlSession.getMapper(NewsMapper.class);
		
		newsMapper.updateNews(news);
		
		// 4. 提交事务
		sqlSession.commit();
		// 5. 关闭资源
		sqlSession.close();	
		
		/*
		 * DEBUG [main] org.itcheng.app.dao.NewsMapper.updateNews ==>  Preparing: update news_inf set news_title = ?, news_content = ?, happen_season=?, record_season=? where news_id=? 
		 * DEBUG [main] org.itcheng.app.dao.NewsMapper.updateNews ==> Parameters: 修改的标题3(String), 修改的内容(String), 2(Integer), FALL(String), 1(Integer)
		 * DEBUG [main] org.itcheng.app.dao.NewsMapper.updateNews <==    Updates: 1
		 * */
	
	}
	
	public static void selectNews(SqlSession sqlSession)
	{
		// 此处的NewsMapper只是一个接口
		// MyBatis会使用JDK的动态代理为Mapper接口生成实现类
		NewsMapper newsMapper = sqlSession.getMapper(NewsMapper.class);
		System.out.println(newsMapper.getClass());
		List<?> list = newsMapper.findNews(-1);
		list.forEach(e -> {
			News news = (News) e;
			System.out.println(news.getHappenSeason() + "-->"
					+ news.getRecordSeason());
		});
		
		System.out.println(list);
		
		// 4. 提交事务
		sqlSession.commit();
		// 5. 关闭资源
		sqlSession.close();	
		/*
		 * class com.sun.proxy.$Proxy17
		 * DEBUG [main] org.itcheng.app.dao.NewsMapper.findNews ==>  Preparing: select news_id id, news_title title, news_content content, happen_season happenSeason, record_season recordSeason from news_inf where news_id > ? 
		 * DEBUG [main] org.itcheng.app.dao.NewsMapper.findNews ==> Parameters: -1(Integer)
		 * DEBUG [main] org.itcheng.app.dao.NewsMapper.findNews <==      Total: 1
		 * SUMMER-->FALL
		 * [org.itcheng.app.domain.News@50eca7c6]
		 * 
		 * */
	}
}

映射文件

DOCTYPE mapper
	PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
	"http://mybatis.org/dtd/mybatis-3-mapper.dtd">
	
<mapper namespace="org.itcheng.app.dao.NewsMapper">
	
	<insert id="saveNews">
		insert into news_inf values (null, #{title}, #{content}, 
		#{happenSeason, typeHandler=org.apache.ibatis.type.EnumOrdinalTypeHandler,
		javaType=org.itcheng.app.domain.Season}, #{recordSeason})
	insert>
	
	
	<update id="updateNews">
		update news_inf set news_title = #{title}, news_content = #{content},
		happen_season=#{happenSeason, typeHandler=org.apache.ibatis.type.EnumOrdinalTypeHandler,
		javaType=org.itcheng.app.domain.Season}, record_season=#{recordSeason}
		where news_id=#{id}
	update>
	
	
	<select id="findNews" resultMap="newsMap">
		select news_id id, news_title title, news_content content, 
		happen_season happenSeason, record_season recordSeason
		from news_inf where news_id > #{id}		
	select>
	
	<resultMap type="news" id="newsMap">
		
		<result column="id" property="id"/>
		<result column="happenSeason" property="happenSeason" 
			typeHandler="org.apache.ibatis.type.EnumOrdinalTypeHandler"
			javaType="org.itcheng.app.domain.Season"/>
	resultMap>
mapper>

用户类

package org.itcheng.app.domain;

// 默认的别名是news
public class News
{
	private Integer id;
	private String title;
	private String content;
	// 它是一个枚举类型的属性（程序要求happenSeason保存枚举的序号值）
	private Season happenSeason;//数据库类型 varchar(255)
	// 它是一个枚举类型的属性（程序要求recordSeason保存枚举的名称）
	private Season recordSeason;//数据库类型 varchar(255)
	
	//添加set和get方法，有参无参构造器
}

自定义枚举类

package org.itcheng.app.domain;

public enum Season
{
	SPRING, SUMMER, FALL, WINTER;
}

表结构

create table news_inf
(
 news_id int primary key auto_increment,
 news_title varchar(255),
 news_content varchar(255),
 happen_season varchar(255),
 record_season varchar(255) 
);