m'ybatis 一对一 一对多 配置详解

javabean：

package com.me.model;

import java.io.serializable;
import java.util.date;
import java.util.list;

public class user implements serializable {  
      
    /**
     * 
     */
    private static final long serialversionuid = 1l;
    private int id;  
    private string username;  
    private date birthday;  
    private string sex;  
    private string address; 
    //一對一 放入對象
    private morder morder;
    //一對多 放入對象集合
    private list<home> homelist;
    
    
      
   
    public list<home> gethomelist() {
        return homelist;
    }
    public void sethomelist(list<home> homelist) {
        this.homelist = homelist;
    }
    public morder getmorder() {
        return morder;
    }
    public void setmorder(morder morder) {
        this.morder = morder;
    }
    public static long getserialversionuid() {
        return serialversionuid;
    }
    public int getid() {  
        return id;  
    }  
    public void setid(int id) {  
        this.id = id;  
    }  
    public string getusername() {  
        return username;  
    }  
    public void setusername(string username) {  
        this.username = username;  
    }  
    public date getbirthday() {  
        return birthday;  
    }  
    public void setbirthday(date birthday) {  
        this.birthday = birthday;  
    }  
    public string getsex() {  
        return sex;  
    }  
    public void setsex(string sex) {  
        this.sex = sex;  
    }  
    public string getaddress() {  
        return address;  
    }  
    public void setaddress(string address) {  
        this.address = address;  
    }
    @override
    public string tostring() {
        return "user [id=" + id + ", username=" + username + ", birthday="
                + birthday + ", sex=" + sex + ", address=" + address
                + ", morder=" + morder + ", homelist=" + homelist + "]";
    }
    
    
      
}  

package com.me.model;

public class morder {
    
    private int orderid;
    private string ordername;
    private string ordermessage;
    public int getorderid() {
        return orderid;
    }
    public void setorderid(int orderid) {
        this.orderid = orderid;
    }
    public string getordername() {
        return ordername;
    }
    public void setordername(string ordername) {
        this.ordername = ordername;
    }
    public string getordermessage() {
        return ordermessage;
    }
    public void setordermessage(string ordermessage) {
        this.ordermessage = ordermessage;
    }
    
    

}

package com.me.model;

public class home {
	
	private int homeid;
	private string homename;
	public int gethomeid() {
		return homeid;
	}
	public void sethomeid(int homeid) {
		this.homeid = homeid;
	}
	public string gethomename() {
		return homename;
	}
	public void sethomename(string homename) {
		this.homename = homename;
	}
	
	

}

　　mapper.xml 代码

<!-- collection ：collection属性的值有三个分别是list、array、map三种， 分别对应的参数类型为：list、数组、map集合，我在上面传的参数为数组，所以值为array 
        item ： 表示在迭代过程中每一个元素的别名 index ：表示在迭代过程中每次迭代到的位置（下标） open ：前缀 close ：后缀 separator 
        ：分隔符，表示迭代时每个元素之间以什么分隔 -->
    <delete id="deletesome">
        delete from user where id in
        <foreach collection="list" item="id" index="index" open="("
            close=")" separator=",">
            #{id}
        </foreach>
    </delete>
    
<!-- 关联查询 -->    
    <!-- 關聯查詢 1對1 -->
    <select id="selectgl" resultmap="userrsultmap">
        select * from user u,morder m
        where u.oid=m.order_id
    </select>
    <resultmap type="com.me.model.user" id="userrsultmap">
        <id property="id" column="id" />
        <result column="username" property="username" />
        <result column="birthday" property="birthday" />
        <result column="sex" property="sex" />
        <result column="address" property="address" />

        <association property="morder" javatype="com.me.model.morder">
            <id column="order_id" property="orderid" />
            <result column="order_name" property="ordername" />
            <result column="order_message" property="ordermessage" />
        </association>
    </resultmap>
    <!-- 關聯查詢 1對多 -->
    <select id="selectgl2" resultmap="userrsultmap2">
        select * from user u,home h where u.hid=h.home_id;    
    </select>
    <resultmap type="com.me.model.user" id="userrsultmap2">
        <id property="id" column="id" />
        <result column="username" property="username" />
        <result column="birthday" property="birthday" />
        <result column="sex" property="sex" />
        <result column="address" property="address" />

        <collection property="homelist" oftype="com.me.model.home">
            <id property="homeid" column="home_id" />
            <result property="homename" column="home_name" />
        </collection>
    </resultmap>

图文解释：

测试：

//關聯查詢 1 to 多
    @test
    public void selectgl2(){
        try {
            inputstream = resources.getresourceasstream(resource);
            // 创建会话工厂，传入mybatis的配置文件信息
            sqlsessionfactory sqlsessionfactory = new sqlsessionfactorybuilder()
                    .build(inputstream);
            // 通过工厂得到sqlsession
            sqlsession = sqlsessionfactory.opensession();
            list<user> list = sqlsession.selectlist("test.selectgl2");
            for (user u : list) {
                system.err.println(u.gethomelist().get(0).gethomename());
            }

        } catch (ioexception e) {
            e.printstacktrace();
        } finally {
            // 释放资源
            sqlsession.close();
        }
    }

结果：

22:47:17.005 [main] debug org.apache.ibatis.logging.logfactory - logging initialized using 'class org.apache.ibatis.logging.slf4j.slf4jimpl' adapter.
22:47:17.140 [main] debug o.a.i.d.pooled.pooleddatasource - pooleddatasource forcefully closed/removed all connections.
22:47:17.140 [main] debug o.a.i.d.pooled.pooleddatasource - pooleddatasource forcefully closed/removed all connections.
22:47:17.140 [main] debug o.a.i.d.pooled.pooleddatasource - pooleddatasource forcefully closed/removed all connections.
22:47:17.140 [main] debug o.a.i.d.pooled.pooleddatasource - pooleddatasource forcefully closed/removed all connections.
22:47:17.215 [main] debug o.a.i.t.jdbc.jdbctransaction - opening jdbc connection
22:47:17.420 [main] debug o.a.i.d.pooled.pooleddatasource - created connection 518522822.
22:47:17.420 [main] debug o.a.i.t.jdbc.jdbctransaction - setting autocommit to false on jdbc connection [com.mysql.jdbc.jdbc4connection@1ee807c6]
22:47:17.421 [main] debug test.selectgl2 - ==> preparing: select * from user u,home h where u.hid=h.home_id;
22:47:17.444 [main] debug test.selectgl2 - ==> parameters:
22:47:17.461 [main] debug test.selectgl2 - <== total: 4
sasadasd
22:47:17.462 [main] debug o.a.i.t.jdbc.jdbctransaction - resetting autocommit to true on jdbc connection [com.mysql.jdbc.jdbc4connection@1ee807c6]
22:47:17.462 [main] debug o.a.i.t.jdbc.jdbctransaction - closing jdbc connection [com.mysql.jdbc.jdbc4connection@1ee807c6]
22:47:17.463 [main] debug o.a.i.d.pooled.pooleddatasource - returned connection 518522822 to pool.

 

更多可以参考：https://www.cnblogs.com/xdp-gacl/p/4264440.html