mybatis入门教程(一)
1. MyBatis是什么?
MyBatis 本是apache的一个开源项目iBatis, 2010年这个项目由apache software foundation 迁移到了google code，并且改名为MyBatis 。
iBATIS一词来源于“internet”和“abatis”的组合，是一个基于Java的持久层框架。iBATIS提供的持久层框架包括SQL Maps和Data Access Objects（DAO）
2. MyBatis quick start
2.1 如何获取MyBatis的支持
如果你还在用传统的方式开发程序那么你需要到mybatis官网上下载对应的jar包，对应官方网址为:http://blog.mybatis.org/
如果你是在使用maven管理你得项目，那么恭喜你，下面我们的例子就是使用maven构建项目。
在你的项目的pom.xml中添加dependency:
<dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>4.7</version> <scope>test</scope> </dependency> <dependency> <groupId>org.mybatis</groupId> <artifactId>mybatis</artifactId> <version>3.2.6</version> </dependency> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <version>5.1.30</version> </dependency> <dependency> <groupId>log4j</groupId> <artifactId>log4j</artifactId> <version>1.2.17</version> </dependency>
2.2 MyBatis的simple CURD
首先我们需要建立一个数据库，创建测试表:
drop database bbs; create database bbs character set utf8; use bbs; /*alter database bbs character set utf8;*/s /* Posts 发的帖子信息 Post_id 帖子的id int Post_Title 帖子的标题 nvarchar Post_BiBoid 帖子所属父版块id int Post_SmBoid 帖子所属子版块id int Post_admin 发帖者姓名 nvarchar Post_createtime 发帖时间 datetime Post_updatetime 更新时间 datetime Post_content 帖子内容 nvarchar Post_goodcount 帖子的好评数 int Post_badcount 帖子的坏评数 int Post_reward 帖子的总共悬赏分（吸引浏览） int Post_score 帖子悬赏分所剩下的分数 int Post_ispay 是否结贴 bit Post_islocked 是否帖子被锁定 bit */ drop table posts; create table posts( id int primary key auto_increment, title varchar(100), biboid int, smboid int, admin varchar(50), createtime datetime, updatetime datetime, context text, goodcount int, badcount int, reward int, score int, ispay bit, islocked bit )ENGINE=InnoDB DEFAULT CHARSET=utf8;
新建一个MyBatis的主配置文件: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> <settings> <!-- changes from the defaults for testing --> <setting name="cacheEnabled" value="false" /> <setting name="useGeneratedKeys" value="true" /> <setting name="defaultExecutorType" value="REUSE" /> </settings> <typeAliases> <!-- 实体类的别名 --> <typeAlias alias="Posts" type="com.mscncn.batis.model.Posts"/> </typeAliases> <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://127.0.0.1:3306/bbs"/> <property name="username" value="pwpw1218"/> <property name="password" value="pwpw1218"/> </dataSource> </environment> </environments> <mappers> <mapper resource="com/mscncn/batis/mapper/config/PostsMapper.xml" /> </mappers> </configuration>
新建一个model类:Posts
package com.mscncn.batis.model;
import java.sql.Date;
/**
* 发的帖子信息
* @author king-pan
* @version 1.0
*
*/
public class Posts {
private int id;
private String title;
private int biboid;
private int smboid;
private Date createTime;
private Date updateTime;
private String context;
private int goodCount;
private int badCount;
private int reward;
private int score;
private boolean isPay;
private boolean isLocked;//自己提供getter，setter方法
public Posts(){}
public Posts(String title,String context){
this.title=title;
this.context=context;
}
public Posts(int id,String title,String context){
this.id=id;
this.title=title;
this.context=context;
}
}
新建一个PostMapper.java 定义对Posts表操作的接口:
package com.mscncn.batis.mapper;
import java.util.List;
import java.util.Map;
import com.mscncn.batis.model.Pager;
import com.mscncn.batis.model.Posts;
public interface PostsMapper{
public void addPosts(Posts posts);
public Posts getPostsById(int id);
public Posts getPostsByTitle(String title);
public void updatePosts(Posts posts);
public void deletePosts(int id);
public void batchUpdate(List<Posts> list);
public List<Posts> getList();
public List<Posts> getListByPage(Pager pager);
public Posts getByParams(Posts posts);
public Posts getByChoose(Posts post);
public Posts trimTest(Posts posts);
public void update(Posts post);
public void updateArray(int[]ary);
public Posts getByMap(Map<String,Object> map);
}
SQL映射:
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.mscncn.batis.mapper.PostsMapper">
<!-- 这里namespace必须是PostsMapper接口的路径，不然要运行的时候要报错 “is not known to the MapperRegistry”-->
<insert id="addPosts" parameterType="Posts">
insert into posts(title,context) values(#{title},#{context})
<!-- 这里sql结尾不能加分号，否则报“ORA-00911”的错误 -->
</insert>
<!-- 这里的id必须和PostsMapper接口中的接口方法名相同，不然运行的时候也要报错 -->
<select id="getPostsById" resultType="Posts" parameterType="int">
select * from posts where id=#{id}
</select>
<select id="getPostsByTitle" resultType="Posts" parameterType="java.lang.String">
select * from posts where title like #{title}
</select>
<!-- 如果方法没有参数，那么就不需要parameterType -->
<select id="getList" resultMap="postList">
select * from posts
</select>
<update id="updatePosts" parameterType="Posts">
update posts set context=#{context} where id=#{id}
</update>
<delete id="deletePosts" parameterType="int">
<![CDATA[
delete from posts where id=#{id}
]]>
</delete>
<update id="batchUpdate" parameterType="java.util.List">
update posts set badcount=3,goodcount=5 where id in
<foreach collection="list" item="item" open="(" close=")" index="index" separator=",">
#{item.id}
</foreach>
</update>
<resultMap type="Posts" id="postList">
<id column="id" property="id"/>
<result column="title" property="title" />
<result column="context" property="context" />
</resultMap>
</mapper>
MyBatisUtil代码如下:
package com.mscncn.batis.util;
import java.io.IOException;
import java.io.Reader;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
public class MyBatisUtil {
private final static SqlSessionFactory sqlSessionFactory;
static {
String resource = "mybatis-config.xml";
Reader reader = null;
try {
reader = Resources.getResourceAsReader(resource);
} catch (IOException e) {
System.out.println(e.getMessage());
e.printStackTrace();
}
sqlSessionFactory = new SqlSessionFactoryBuilder().build(reader);
}
public static SqlSessionFactory getSqlSessionFactory() {
return sqlSessionFactory;
}
}
测试代码如下:
package com.mscncn.batis;
import java.util.List;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.junit.Test;
import com.mscncn.batis.mapper.PostsMapper;
import com.mscncn.batis.model.Posts;
import com.mscncn.batis.util.MyBatisUtil;
public class PostsMapperTest {
static SqlSessionFactory sqlSessionFactory = null;
static {
sqlSessionFactory = MyBatisUtil.getSqlSessionFactory();
}
@Test
public void testAdd() {
SqlSession sqlSession = sqlSessionFactory.openSession();
try {
PostsMapper mapper = sqlSession.getMapper(PostsMapper.class);
Posts posts=new Posts("Spring test", "这是一个mybatis测试");
mapper.addPosts(posts);
sqlSession.commit();//这里一定要提交，不然数据进不去数据库中
} finally {
sqlSession.close();
}
}
@Test
public void getUser() {
SqlSession sqlSession = sqlSessionFactory.openSession();
try {
PostsMapper mapper = sqlSession.getMapper(PostsMapper.class);
Posts posts=mapper.getPostsById(1);
System.out.println(posts.getContext());
} finally {
sqlSession.close();
}
}
@Test
public void getUserByTitle() {
SqlSession sqlSession = sqlSessionFactory.openSession();
try {
PostsMapper mapper = sqlSession.getMapper(PostsMapper.class);
Posts posts=mapper.getPostsByTitle("Spring test");
System.out.println(posts.getContext());
} catch(Exception e){
e.printStackTrace();
}
finally {
sqlSession.close();
}
}
@Test
public void getListTest() {
SqlSession sqlSession = sqlSessionFactory.openSession();
try {
PostsMapper mapper = sqlSession.getMapper(PostsMapper.class);
List<Posts> posts=mapper.getList();
System.out.println(posts.size());
System.out.println(posts.get(0).getId());
System.out.println(posts.get(1).getContext());
} catch(Exception e){
e.printStackTrace();
}
finally {
sqlSession.close();
}
}
@Test
public void updatePostsTest() {
SqlSession sqlSession = sqlSessionFactory.openSession();
try {
PostsMapper mapper = sqlSession.getMapper(PostsMapper.class);
Posts posts=new Posts(1, "22", "mybatis 跟新数据库操作");
mapper.updatePosts(posts);
sqlSession.commit();
} catch(Exception e){
e.printStackTrace();
}
finally {
sqlSession.close();
}
}
@Test
public void deletePostsTest() {
SqlSession sqlSession = sqlSessionFactory.openSession();
try {
PostsMapper mapper = sqlSession.getMapper(PostsMapper.class);
mapper.deletePosts(3);
sqlSession.commit();
} catch(Exception e){
e.printStackTrace();
}
finally {
sqlSession.close();
}
}
@Test
public void batchTest(){
SqlSession sqlSession = sqlSessionFactory.openSession();
try {
PostsMapper mapper = sqlSession.getMapper(PostsMapper.class);
List<Posts> list=mapper.getList();
int index=0;
for(Posts ps:list){
ps.setBadCount(++index);
ps.setGoodCount(index);
}
mapper.batchUpdate(list);
sqlSession.commit();
} catch(Exception e){
e.printStackTrace();
}
finally {
sqlSession.close();
}
}
}
注意： 在maven中测试时，一定要记得把相应的配置文件拷贝到src/test/resources目录下，不然在使用MyBatis框架时一直抱错，错误信息如下:
MyBatis could not find resource …..