mybatis一对多查询过程只查询了一个结果

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;
}

@Override
public 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;
@Override
public 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;
}
@Override
public 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;

@Before
public 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
}

@Test
public 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());

}

@After
public 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: 2
User [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