Mybatis学习随笔

使用Mybatis步骤

创建Java项目

mysql建表 blog

建立映射导包jar

实体类 blog.java  set/get/tostring/构造函数

　　与数据库中表一一对应

package com.hut.bean;

public class Blog {

    private int id;
    private String name;
    private String title;
    
    /*
     * get/set 
     */
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public String getTitle() {
        return title;
    }
    public void setTitle(String title) {
        this.title = title;
    }
    
    /*
     * 输出
     */
    @Override
    public String toString() {
        return "blog [id=" + id + ", name=" + name + ", title=" + title + "]";
    }
    /*
     * 构造方法 无参/含参
     */
    public Blog(int id, String name, String title) {
        super();
        this.id = id;
        this.name = name;
        this.title = title;
    }
    
    public Blog() {
        super();
        // TODO 自动生成的构造函数存根
    }
    
}

测试类 test.java  调用blogmapper

配置文件 mybatis-config.xml

　　连接数据库

　　加载mapper.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>
 <typeAliases> <package name = "com.hut.bean"/></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://Localhost:3306/blog"/>
        <property name="username" value="root"/>
        <property name="password" value="admin"/>
      </dataSource>
    </environment>
  </environments>
  <mappers>
    <mapper resource="com/hut/dao/BlogMapper.xml"/>
  </mappers>
</configuration>

映射器接口 blogmapper.java  

package com.hut.dao;

import java.util.List;

import org.apache.ibatis.annotations.Param;

import com.hut.bean.Blog;

public interface BlogMapper {
    
    List<Blog> selectname(String name);
    //模糊查询
    List<Blog> select_id_name(@Param("id")int id ,@Param("name") String name);
    //多条件查询
    void deleteblog(String name);
    //删除
    void addblog(Blog blog);
    //添加
    void updateblog(Blog blog);
    //更新
    List<Blog> selectall();
    //打印全部blog
    
    List<Blog> selectblog(@Param("name")String name , @Param("title")String title);
    //if 动态sql
    
    List<Blog> getBlogByIds(@Param("ids") List<Integer> ids);
    //foreach
}

映射器blogmapper.xml 

　　表-实体类关联

　　SQL语句-将数据映射为对象

　　编写crud方法

　　　　insert/delete/select/update

<?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.hut.dao.BlogMapper">
<!-- sql语句 -->

  <select id="select_id_name" resultType="blog" >
    select * from Blog where id >#{id} and name like concat('%',#{name},'%')
  </select>
  
  <select id="selectname" resultType="blog">
    select * from Blog where name like '%${name}%'
  </select>
  
    <insert id="addblog" >
    insert into Blog (id,name,title) values (#{id},#{name},#{title})
    </insert>
      
    <delete id="deleteblog"  >
        delete from Blog where name = #{name}
    </delete>
    
    <update id="updateblog">
        update blog set
        name = #{name},
        title = #{title}
        where id = #{id}
    </update>
    
    <select id="selectall" resultType = "blog">
        select * from blog
    </select>
    
    <select id = "selectblog" resultType = "blog">
        select * from blog
        <where>
        <if test = "name != null">
        name like '%${name}%'
        </if>
        <if test = "title != null">
        title like '%${title}%'
        </if>
        </where>
    </select>
    
    <select id="getBlogByIds" resultType="blog">
    select * from blog
    where id in
      <foreach collection="ids" item="item"
              open="(" separator="," close=")">
              #{item}
      </foreach>
    </select>
</mapper>