JavaWeb学习笔记-mybatis-19-一对一使用resultMap

使用resultMap将查询结果中的订单信息映射到orders对象中，在orders类中添加user属性，将关联查询出来的用户信息映射到order对象中的user属性中

需要orders类中添加user属性

public class Orders {
private Integer id;

private Integer userId;

private String number;

private Date createtime;

private String note;

//添加用户信息
private User user;

public User getUser() {
return user;
}

public void setUser(User user) {
this.user = user;
}

public Integer getId() {
return id;
}

public void setId(Integer id) {
this.id = id;
}

public Integer getUserId() {
return userId;
}

public void setUserId(Integer userId) {
this.userId = userId;
}

public String getNumber() {
return number;
}

public void setNumber(String number) {
this.number = number;
}

public Date getCreatetime() {
return createtime;
}

public void setCreatetime(Date createtime) {
this.createtime = createtime;
}

public String getNote() {
return note;
}

public void setNote(String note) {
this.note = note;
}
}

mapper.xml

<!--订单查询用户关联的resultMap
将整个查询结果映射到Orders中-->
<resultMap id="OrdersUserResultMap" type="com.sws.entity.Orders">
<!--配置映射订单信息-->
<!--id:指定查询列的唯一标示-->
<id column="id" property="id"/>
<result column="user_id" property="userId"/>
<result column="number" property="number"/>
<result column="createtime" property="createtime"/>
<result column="note" property="note"/>
<!--配置映射关系的用户信息-->
<!--association:用于映射关系查询单个对象的信息
property:要将关联查询的用户信息映射到Order中的那个属性-->
<association property="user" javaType="com.sws.entity.User">
<!--id:关联查询用户的唯一标识
column:指定唯一标识用户信息的列
property:映射到user的哪个属性-->
<id column="user_id" property="id"/>
<result column="username" property="username"/>
<result column="sex" property="sex"/>
<result column="address" property="address"/>
</association>
</resultMap>

<select id="findOrdersUseresultMap" resultMap="OrdersUserResultMap">
select orders.*,user.username,user.sex,user.address from orders,user wher
9c40
e orders.user_id = user.id
</select>

OrdersMapper.java

public List<Orders> findOrdersUserResultMap()throws Exception;