mybatis一对多查询过程只查询了一个结果

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新学mybatis，在一对多关联查询过程中出现了一点bug

首先附上我的代码

User.java

public class User{public User(){// TODO Auto-generated constructor stub}private String userName;private String passWord;private int id;private Car car;private List<Order> orders;//订单public String getUserName(){return userName;}public void setUserName(String userName){this.userName = userName;}@Overridepublic String toString(){return "User [userName=" + userName + ", passWord=" + passWord + ", id=" + id + ", car=" + car + ", orders="+ orders + ", age=" + age + "]";}public List<Order> getOrders(){return orders;}public void setOrders(List<Order> orders){this.orders = orders;}public Car getCar(){return car;}public void setCar(Car car){this.car = car;}public String getPassWord(){return passWord;}public void setPassWord(String passWord){this.passWord = passWord;}public int getId(){return id;}public void setId(int id){this.id = id;}public int getAge(){return age;}public void setAge(int age){this.age = age;}private int age;}

Car.java

public class Car{private int id;private int pid;private String name;@Overridepublic String toString(){return "Car [id=" + id + ", pid=" + pid + ", name=" + name + "]";}public int getId(){return id;}public void setId(int id){this.id = id;}public int getPid(){return pid;}public void setPid(int pid){this.pid = pid;}public String getName(){return name;}public void setName(String name){this.name = name;}public Car(){// TODO Auto-generated constructor stub}}

Order.java//订单类

public class Order{private int id;private int price;private int cid;public void setId(int id){this.id = id;}@Overridepublic String toString(){return "Order [id=" + id + ", price=" + price + ", cid=" + cid + "]";}public int getId(){return id;}public int getPrice(){return price;}public void setPrice(int price){this.price = price;}public int getCid(){return cid;}public void setCid(int cid){this.cid = cid;}}

然后是user,orders,car的三个表的表结构

出于清晰明了，我这里直接截图

user 表:

car表

orders表

UserMapper.xml中的相关查询代码如下:

<select id="selectUser" resultMap="userMap">    select * from user u inner join car on u.id=pid inner join orders on u.id=cid where u.id = #{id}  </select>    <resultMap type="u" id="userMap">  <id column="id" property="id"/>  <result column="userName" property="userName"/>  <result column="passWord" property="passWord"/>  <result column="age" property="age"/>   <association property="car" javaType="com.zzc.po.Car">//一对一的关联pojo   <id column="id" property="id"/>  <result column="name" property="name"/>  <result column="pid" property="pid"/>  </association>  <collection property="orders"   ofType="com.zzc.po.Order" >//一对多的关联pojo  <id column="id" property="id"/>  <result column="cid" property="cid"/>  <result column="price" property="price"/>  </collection>  </resultMap>

测试:

SqlSession  session = null;@Beforepublic void before() throws IOException{String resource = "mybatis-config.xml";InputStream inputStream = Resources.getResourceAsStream(resource);SqlSessionFactory sqlSessionFactory  = new SqlSessionFactoryBuilder().build(inputStream);session = sqlSessionFactory.openSession();}public Tests(){// TODO Auto-generated constructor stub}@Testpublic void demo1() throws IOException{UserMapper mapper = session.getMapper(UserMapper.class);User user = mapper.selectUser(2);System.out.println(user);//System.out.println(mapper.insertUser("323", "111", 11));//User u = new User();//u.setPassWord("asas");//u.setUserName("q323");//System.out.println(mapper.insertUser2(u));//System.out.println(mapper.insertUserGetKey(u));//System.out.println(u.getId());}@Afterpublic void after(){session.commit();session.close();}

输出台部分输出:

2016 十一月 28 18:13:25,622 DEBUG selectUser:145 - ==>  Preparing: select * from user u inner join car on u.id=pid inner join orders on u.id=cid where u.id = ? 2016 十一月 28 18:13:25,691 DEBUG selectUser:145 - ==> Parameters: 2(Integer)2016 十一月 28 18:13:25,719 DEBUG selectUser:145 - <==      Total: 2User [userName=www, passWord=123, id=2, car=Car [id=2, pid=2, name=rrr], orders=[Order [id=2, price=2000, cid=2]], age=101]

在navicat执行该sql:

可以看到这个user下面有两个与之关联的订单但是java执行却只显示一个

这不是mybatis配置问题也不是sql语句问题

而是user表和ordesr表的主键名都为id所引起的，不知道mybatis内部是什么机制去处理的改为不同名的主键便ok了

具体原因得在日后深入源码学习再来这里公布

mybatis一对多具体的请看:http://www.tuicool.com/articles/M3QJvu

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