搭建MySQL环境
CREATE TABLE `blog` (
`id` VARCHAR(50) NOT NULL COMMENT '博客id',
`title` VARCHAR(100) NOT NULL COMMENT '博客标题',
`author` VARCHAR(30) NOT NULL COMMENT '博客作者',
`create_time` datetime NOT NULL COMMENT '博客作者',
`views` INT(30) NOT NULL COMMENT '浏览量'
)ENGINE=INNODB DEFAULT CHARSET=utf8
IDutils工具包
package com.zzqsmile.utils;
import org.junit.Test;
import java.util.UUID;
@SuppressWarnings("all") //抑制警告
public class IDutils {
public static String getID(){
return UUID.randomUUID().toString().replaceAll("-","");
}
@Test
public void test(){
System.out.println(IDutils.getID());
}
}
步骤
1.导包
pom.xml
2.编写配置文件
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">
<!--核心配置文件-->
<configuration>
<!-- 引入外部配置文件-->
<properties resource="db.properties"/>
<!-- 可以给实体类起别名-->
<typeAliases>
<package name="com.zzqsmile.pojo"/>
<!-- <typeAlias type="com.zzqsmile.pojo.User" alias="User"/>-->
</typeAliases>
<environments default="development">
<environment id="development">
<transactionManager type="JDBC"/>
<dataSource type="POOLED">
<property name="driver" value="${driver}"/>
<property name="url" value="${url}"/>
<property name="username" value="${username}"/>
<property name="password" value="${password}"/>
<!-- <property name="driver" value="com.mysql.cj.jdbc.Driver"/>-->
<!-- <property name="url" value="jdbc:mysql://localhost:3306/mybatis?useUnicode=true&characterEncoding=utf-8&useSSL=false"/>-->
<!-- <property name="username" value="root"/>-->
<!-- <property name="password" value="root"/>-->
</dataSource>
</environment>
</environments>
<!-- 绑定接口-->
<mappers>
<mapper class="com.zzqsmile.dao.BlogMapper"></mapper>
</mappers>
</configuration>
db.properties
driver=com.mysql.cj.jdbc.Driver
url=jdbc:mysql://localhost:3306/mybatis?useUnicode=true&characterEncoding=utf-8&useSSL=false
username=root
password=root
3.编写实体类
package com.zzqsmile.pojo;
import lombok.Data;
import java.util.Date;
@Data
public class Blog {
private String id;
private String title;
private String author;
private Date createTime;
private int views;
}
4.编写实体类对应的Mapper接口和 Mapper.xml文件
BlogMapper:
package com.zzqsmile.dao;
import com.zzqsmile.pojo.Blog;
import java.util.List;
import java.util.Map;
public interface BlogMapper {
//插入数据
int addBlog(Blog blog);
//查询博客
List<Blog> queryBlogIF(Map map);
//选择查询
List<Blog> queryBlogChoose(Map map);
//更新博客
int updateBlog(Map map);
//ForEach
List<Blog> queryBlogForEach(Map map);
}
BlogMapper.xml:
<?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.zzqsmile.dao.BlogMapper">
<insert id="addBlog" parameterType="blog">
insert into mybatis.blog(id,title,author,create_time,views)
values (#{id},#{title},#{author},#{createTime},#{views})
</insert>
</mapper>
- if
BlogMapper.xml
<mapper>
<select id="queryBlogIF" parameterType="map" resultType="blog">
select * from mybatis.blog where 1=1
<if test="title != null">
AND title like #{title}
</if>
<if test="author != null">
AND author like #{author}
</if>
</select>
</mapper>
优化where
<select id="queryBlogIF" parameterType="map" resultType="blog">
select * from mybatis.blog
<where>
<if test="title != null">
AND title like #{title}
</if>
<if test="author != null">
AND author like #{author}
</if>
</where>
</select>
测试：
@Test
public void queryBlogIF(){
SqlSession sqlSession = MybatisUtils.getSqlSession();
BlogMapper mapper = sqlSession.getMapper(BlogMapper.class);
HashMap map = new HashMap<>();
map.put("title","Spring");
map.put("author","zzqsmile");
List<Blog> blogs = mapper.queryBlogIF(map);
for (Blog blog : blogs) {
System.out.println(blog);
}
sqlSession.close();
}
- choose
<select id="queryBlogChoose" parameterType="map" resultType="blog">
select * from mybatis.blog
<where>
<choose>
<when test="title != null">
title = #{title}
</when>
<when test="author != null">
and author = #{author}
</when>
<otherwise>
and views = #{views}
</otherwise>
</choose>
</where>
</select>
- updateBlog()
<update id="updateBlog" parameterType="map">
update mybatis.blog
<set>
<if test="title != null">
title = #{title},
</if>
<if test="author != null">
author = #{author}
</if>
</set>
where id = #{id}
</update>
</mapper>
trim标签可以自定义
- 动态SQLForEach
BlogMapper.xml
<!-- select * from mybatis.blog where 1=1 and (id=1 or id =2 or id=3)-->
<select id="queryBlogForEach" parameterType="map" resultType="blog">
select * from mybatis.blog
<where>
<foreach collection="ids" item="id" open="and (" close=")" separator="or">
id=#{id}
</foreach>
</where>
</select>
测试：
@Test
public void queryBlogForEach(){
SqlSession sqlSession = MybatisUtils.getSqlSession();
BlogMapper mapper = sqlSession.getMapper(BlogMapper.class);
HashMap map = new HashMap<>();
ArrayList<Integer> ids = new ArrayList<>();
ids.add(1);
ids.add(2);
ids.add(3);
map.put("ids", ids);
List<Blog> blogs = mapper.queryBlogForEach(map);
for (Blog blog : blogs) {
System.out.println(blog);
}
sqlSession.close();
}
