Mybatis中输入输出映射与动态Sql图文详解

package cn.mybatis.po;

public class userpojo extends user{

  private user user;

  public void setuser(user user) {

  this .user = user;

  }

  public user getuser() {

  return user;

  }

}

userpojo

package cn.mybatis.po;

public class uservo {

  private userpojo userpojo;

  public userpojo getuserpojo() {

  return userpojo;

  }

  public void setuserpojo(userpojo userpojo) {

  this .userpojo = userpojo;

  }

}

uservo

//测试包装类型的查询

  public list<userpojo> finduserlist(uservo uservo) throws exception;

@test

  public void testfinduserlist() throws exception {

  sqlsession sqlsession = sqlsessionfactory.opensession();

  usermapper usermapper = sqlsession.getmapper(usermapper. class );

  userpojo userpojo = new userpojo();

  uservo uservo = new uservo();

  userpojo.setsex( "男" );

  userpojo.setusername( "u" );

  uservo.setuserpojo(userpojo);

  list<userpojo> userpojolist = usermapper.finduserlist(uservo);

  system.out.println(userpojolist);

  }

select count(*) from t_user

select username from t_user where id = 2

<?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= "cn.mybatis.mapper.usermapper" >

  <!--定义resultmap

  type:resultmap最终映射的java对象类型

  id:对resultmap的标识

  -->

  <resultmap id= "userresultmap" type= "user" >

  <!--id:标识查询结果集中的唯一标识-->

  <id column= "_id" property= "id" ></id>

  <!--result:标识查询结果集中其他列的标识-->

  <result column= "_username" property= "username" ></result>

  <result column= "_password" property= "password" ></result>

  <result column= "_sex" property= "sex" ></result>

  <result column= "_address" property= "address" ></result>

  </resultmap>

  <select id= "finduserbyid_resultmap" parametertype= "int" resultmap= "userresultmap" >

  select id _id, username _username, password _password, address _address, sex _sex from t_user where id = #{id}

  </select>

</mapper>

//测试resultmap

public user finduserbyid_resultmap( int id) throws exception;

@test

  public void testfinduserbyid_resultmap() throws exception {

  sqlsession sqlsession = sqlsessionfactory.opensession();

  usermapper usermapper = sqlsession.getmapper(usermapper. class );

  user user = usermapper.finduserbyid_resultmap( 2 );

  system.out.println(user);

  }

<select id= "finduserlist" parametertype= "cn.mybatis.po.uservo" resulttype= "cn.mybatis.po.userpojo" >

  select * from t_user

  <where>

   < if test= "userpojo != null" >

   < if test= "userpojo.sex != null and userpojo.sex != ''" >

    and sex = #{userpojo.sex}

   </ if >

   < if test= "userpojo.username != null and userpojo.username != ''" >

    and username like '%${userpojo.username}%'

   </ if >

   </ if >

  </where>

  </select>

<!--定义sql片段-->

  <sql id= "query_user_info" >

  < if test= "userpojo != null" >

   < if test= "userpojo.sex != null and userpojo.sex != ''" >

   and sex = #{userpojo.sex}

   </ if >

   < if test= "userpojo.username != null and userpojo.username != ''" >

   and username like '%${userpojo.username}%'

   </ if >

  </ if >

  </sql>

<select id= "finduserlist" parametertype= "cn.mybatis.po.uservo" resulttype= "cn.mybatis.po.userpojo" >

  select * from t_user

  <where>

   <include refid= "query_user_info" ></include>

  </where>

  </select>

<sql id= "query_ids" >

  < if test= "ids != null" >

   <!--

   select * from t_user where 1 = 1 and (id = 1 or id = 2 or id = 3 )

   cilleation: 指定的是输入参数集合的属性名

   item:每次遍历的名称

   open:开始遍历时拼接串

   close:结束遍历时候拼接的串

   separator:遍历的两个对象中间需要拼接的串

   -->

   <foreach collection= "ids" item= "item_id" open= "and (" close= ")" separator= " or " >

   id=#{item_id}

   </foreach>

  </ if >

  </sql>

<select id= "finduserbyids" parametertype= "uservo" resulttype= "userpojo" >

select * from t_user

<where>

  <include refid= "query_ids" ></include>

</where>

</select>