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