MyBatis學習（七）
阿新 • • 發佈：2018-10-18
ppi before 多個 使用 day col util == and 本課程對應視頻教程：http://edu.51cto.com/sd/3ec2c
1、高級查詢
MyBatis作為一個ORM框架，也對sql的高級查詢做了支持，這裏以用戶，訂單，訂單詳情，商品為例講解
案例說明：此案例的業務關系是用戶、訂單、訂單詳情、商品之間的關系、其中
一個訂單只能屬於一個人
一個訂單可以有多個訂單詳情
一個訂單詳情中包含一個商品信息
他們的關系是：
訂單和人是一對一的關系
訂單和訂單詳情是一對多的關系
訂單和商品是多對多的關系
1.1、數據模型分析
1.2、需求分析
一對一查詢：查詢訂單，並且查詢出下單人信息
一對多查詢：查詢訂單，查詢出下單人信息並且查詢出訂單詳情
多對多查詢：查詢訂單，查詢出訂單人信息並且查詢出訂單詳情中的商品數據
1.3、一對一查詢
1.3.1、方式一
將查詢出來字段封裝到一個新的類中，讓這個類的屬性包含所有查詢出來的字段，
它的弊端在於，我的pojo類會急劇增加
先定義一個實體類
package cn.org.kingdom.pojo; public class OrderUser extends User { private int oid; private int userId; private String orderNum; public int getOid() { return oid; } public void setOid(int oid) { this.oid = oid; } public int getUserId() { return userId; } public void setUserId(int userId) { this.userId = userId; } public String getOrderNum() { return orderNum; } public void setOrderNum(String orderNum) { this.orderNum = orderNum; } @Override public String toString() { return "OrderUser [oid=" + oid + ", userId=" + userId + ", orderNum=" + orderNum + ", userid=" + userid + ", userName=" + userName + ", pwd=" + pwd + ", age=" + age + ", sex=" + sex + ", birthday=" + birthday + "]"; } }
定義數據接口
public List<OrderUser> one2one(@Param("orderNum")String orderNum);配置mapper.xml文件（OrderMapper.xml）
<select id="one2one" resultType="OrderUser"> select tb_user.*,tb_order.* from tb_user,tb_order where tb_user.userid = tb_order.user_id and order_number=#{orderNum} </select>
測試類
package cn.org.kingdom.test;
import java.io.InputStream;
import java.util.List;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;
import cn.org.kingdom.mapper.OrderMapper;
import cn.org.kingdom.pojo.OrderUser;
import cn.org.kingdom.pojo.User;
public class MyBatisTest03 {
SqlSessionFactory sqlSessionFactory = null ;
SqlSession sqlSession = null ;
OrderMapper orderMapper = null ;
@Before
public void setUp() throws Exception {
//加載資源
String resource = "mybatis-config.xml";
InputStream inputStream = Resources.getResourceAsStream(resource);
sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
sqlSession = sqlSessionFactory.openSession();
orderMapper = sqlSession.getMapper(OrderMapper.class);
}
@After
public void tearDown() throws Exception {
//關閉
sqlSession.close();
}
@Test
public void testone2one()throws Exception{
List<OrderUser> list = orderMapper.one2one("20180810001");
for (OrderUser u : list) {
System.out.println(u);
}
}
}生成的日誌
DEBUG - Opening JDBC Connection
DEBUG - Created connection 665964512.
DEBUG - Setting autocommit to false on JDBC Connection [oracle.jdbc.driver.T4CConnection@27b1cfe0]
DEBUG - ==> Preparing: select tb_user.*,tb_order.* from tb_user,tb_order where tb_user.userid = tb_order.user_id and order_number=?
DEBUG - ==> Parameters: 20180810001(String)
DEBUG - <== Total: 1
OrderUser [oid=1, userId=0, orderNumber=20180810001, userid=2, userName=阿柯, pwd=123456, age=10, sex=女, birthday=Tue Aug 14 13:45:34 CST 2018]
DEBUG - Resetting autocommit to true on JDBC Connection [oracle.jdbc.driver.T4CConnection@27b1cfe0]
DEBUG - Closing JDBC Connection [oracle.jdbc.driver.T4CConnection@27b1cfe0]
DEBUG - Returned connection 665964512 to pool.1.3.2、采用面向對象的思維
讓一個類持有另外一個類的屬性
定義一個Order類
package cn.org.kingdom.pojo;
import java.io.Serializable;
public class Order implements Serializable {
private int oid;
private int userId;
private String orderNumber;
private User user ;
public int getOid() {
return oid;
}
public void setOid(int oid) {
this.oid = oid;
}
public int getUserId() {
return userId;
}
public void setUserId(int userId) {
this.userId = userId;
}
public String getOrderNumber() {
return orderNumber;
}
public void setOrderNumber(String orderNumber) {
this.orderNumber = orderNumber;
}
public User getUser() {
return user;
}
public void setUser(User user) {
this.user = user;
}
@Override
public String toString() {
return "Order [oid=" + oid + ", userId=" + userId + ", orderNumber="
+ orderNumber + ", user=" + user + "]";
}
}mapper.xml文件
<resultMap type="Order" id="OrderResultMap" autoMapping="true">
<id column="oid" property="oid"/>
<!--
關聯的對象屬性
property：屬性名
javaType:這個屬性屬於什麽類型
autoMapping：自動映射
-->
<association property="user" javaType="User" autoMapping="true">
<id column="userid" property="userid"/>
</association>
</resultMap>
<select id="one2one2" resultMap="OrderResultMap">
select tb_user.*,tb_order.* from tb_user,tb_order
where tb_user.userid = tb_order.user_id and order_number=#{orderNum}
</select>測試類
@Test
public void testone2one2()throws Exception{
List<Order> list = orderMapper.one2one2("20180810001");
for (Order u : list) {
System.out.println(u);
}
}日誌：
DEBUG - ==> Preparing: select tb_user.*,tb_order.* from tb_user,tb_order where tb_user.userid = tb_order.user_id and order_number=?
DEBUG - ==> Parameters: 20180810001(String)
DEBUG - <== Total: 1
Order [oid=1, userId=2, orderNumber=20180810001, user=User [userid=2, userName=阿柯, pwd=123456, age=10, sex=女, birthday=Tue Aug 14 13:45:34 CST 2018]]
DEBUG - Resetting autocommit to true on JDBC Connection [oracle.jdbc.driver.T4CConnection@5bad7476]
DEBUG - Closing JDBC Connection [oracle.jdbc.driver.T4CConnection@5bad7476]
DEBUG - Returned connection 1538094198 to pool.1.4、一對多查詢
一對多查詢：查詢訂單，查詢出下單人信息並且查詢出訂單詳情
sql
select tb_user.*,tb_order.*,tb_orderdetail.*
from tb_user,tb_order,tb_orderdetail
where tb_user.userid = tb_order.user_id
and tb_order.oid = tb_orderdetail.order_id
and order_number =‘20180810001‘創建pojo類
package cn.org.kingdom.pojo;
import java.io.Serializable;
public class Detail implements Serializable{
private int detailId;
private int orderId;
private int productId;
private double price;
private String status;
public Detail() {
super();
}
public int getDetailId() {
return detailId;
}
public void setDetailId(int detailId) {
this.detailId = detailId;
}
public int getOrderId() {
return orderId;
}
public void setOrderId(int orderId) {
this.orderId = orderId;
}
public int getProductId() {
return productId;
}
public void setProductId(int productId) {
this.productId = productId;
}
public double getPrice() {
return price;
}
public void setPrice(double price) {
this.price = price;
}
public String getStatus() {
return status;
}
public void setStatus(String status) {
this.status = status;
}
@Override
public String toString() {
return "Detail [detailId=" + detailId + ", orderId=" + orderId
+ ", productId=" + productId + ", price=" + price + ", status="
+ status + "]";
}
}
然後在Order中加入多的一方的引用
private List<Detail> details ;
public List<Detail> getDetails() {
return details;
}
public void setDetails(List<Detail> details) {
this.details = details;
}mapper.xml文件
<resultMap type="Order" id="OrderResultMap2" autoMapping="true">
<id column="oid" property="oid"/>
<!--
關聯的對象屬性
property：屬性名
javaType:這個屬性屬於什麽類型
autoMapping：自動映射
-->
<association property="user" javaType="User" autoMapping="true">
<id column="userid" property="userid"/>
</association>
<!--
配置多的一方使用collection這個節點
property:集合的屬性名稱
javaType：類型
ofType:集合中元素的類型
-->
<collection property="details" javaType="list" ofType="Detail" autoMapping="true">
<id column="detail_id" property="detailId"/>
</collection>
</resultMap>
<select id = "one2many" resultMap="OrderResultMap2">
select tb_user.*,tb_order.*,tb_orderdetail.*
from tb_user,tb_order,tb_orderdetail
where tb_user.userid = tb_order.user_id
and tb_order.oid = tb_orderdetail.order_id
and order_number =#{orderNum}
</select>測試類
public void testone2many()throws Exception{
List<Order> list = orderMapper.one2many("20180810001");
for (Order u : list) {
System.out.println(u);
}
}日誌信息
DEBUG - Cache Hit Ratio [cn.org.kingdom.mapper.OrderMapper]: 0.0
DEBUG - Opening JDBC Connection
DEBUG - Created connection 15932635.
DEBUG - Setting autocommit to false on JDBC Connection [oracle.jdbc.driver.T4CConnection@f31cdb]
DEBUG - ==> Preparing: select tb_user.*,tb_order.*,tb_orderdetail.* from tb_user,tb_order,tb_orderdetail where tb_user.userid = tb_order.user_id and tb_order.oid = tb_orderdetail.order_id and order_number =?
DEBUG - ==> Parameters: 20180810001(String)
DEBUG - <== Total: 2
Order [oid=1, userId=2, orderNumber=20180810001, user=User [userid=2, userName=阿柯, pwd=123456, age=10, sex=女, birthday=Tue Aug 14 13:45:34 CST 2018], details=[Detail [detailId=1, orderId=1, productId=1, price=8888.0, status=1], Detail [detailId=2, orderId=1, productId=2, price=188.0, status=1]]]
DEBUG - Resetting autocommit to true on JDBC Connection [oracle.jdbc.driver.T4CConnection@f31cdb]
DEBUG - Closing JDBC Connection [oracle.jdbc.driver.T4CConnection@f31cdb]
DEBUG - Returned connection 15932635 to pool.1.5、多對多
多對多查詢：查詢訂單，查詢出訂單人信息並且查詢出訂單詳情中的商品數據
sql語句分析
select tb_user.*,tb_order.*,tb_orderdetail.*,tb_product.*
from tb_user,tb_order,tb_orderdetail,tb_product
where tb_user.userid = tb_order.user_id
and tb_order.oid = tb_orderdetail.order_id
and tb_orderdetail.product_id = tb_product.pid
and order_number =‘20180810001‘接口方法定義
public List<Order> many2many(@Param("orderNum")String orderNum);創建一個pojo類(Product)
package cn.org.kingdom.pojo;
public class Product implements Serializable {
private int pid;
private String pname ;
private double price ;
private String proDetail;
public int getPid() {
return pid;
}
public void setPid(int pid) {
this.pid = pid;
}
public String getPname() {
return pname;
}
public void setPname(String pname) {
this.pname = pname;
}
public double getPrice() {
return price;
}
public void setPrice(double price) {
this.price = price;
}
public String getProDetail() {
return proDetail;
}
public void setProDetail(String proDetail) {
this.proDetail = proDetail;
}
@Override
public String toString() {
return "Product [pid=" + pid + ", pname=" + pname + ", price=" + price
+ ", proDetail=" + proDetail + "]";
}
}在detail類中加入一個Product類的引用
private Product product;
public Product getProduct() {
return product;
}
public void setProduct(Product product) {
this.product = product;
}mapper.xml文件
<resultMap type="Order" id="OrderResultMap3" autoMapping="true">
<id column="oid" property="oid"/>
<!--
關聯的對象屬性
property：屬性名
javaType:這個屬性屬於什麽類型
autoMapping：自動映射
-->
<association property="user" javaType="User" autoMapping="true">
<id column="userid" property="userid"/>
</association>
<!--
配置多的一方使用collection這個節點
property:集合的屬性名稱
javaType：類型
ofType:集合中元素的類型
-->
<collection property="details" javaType="list" ofType="Detail" autoMapping="true">
<id column="detail_id" property="detailId"/>
<association property="product" javaType="Product" autoMapping="true">
<id column="pid" property="pid"/>
</association>
</collection>
</resultMap>
<select id = "many2many" resultMap="OrderResultMap3">
select tb_user.*,tb_order.*,tb_orderdetail.*,tb_product.*
from tb_user,tb_order,tb_orderdetail,tb_product
where tb_user.userid = tb_order.user_id
and tb_order.oid = tb_orderdetail.order_id
and tb_orderdetail.product_id = tb_product.pid
and order_number =#{orderNum}
</select>測試類
@Test
public void testmany2many()throws Exception{
List<Order> list = orderMapper.many2many("20180810001");
for (Order u : list) {
System.out.println(u);
}
}日誌
DEBUG - Opening JDBC Connection
DEBUG - Created connection 462907404.
DEBUG - Setting autocommit to false on JDBC Connection [oracle.jdbc.driver.T4CConnection@1b97680c]
DEBUG - ==> Preparing: select tb_user.*,tb_order.*,tb_orderdetail.*,tb_product.* from tb_user,tb_order,tb_orderdetail,tb_product where tb_user.userid = tb_order.user_id and tb_order.oid = tb_orderdetail.order_id and tb_orderdetail.product_id = tb_product.pid and order_number =?
DEBUG - ==> Parameters: 20180810001(String)
DEBUG - <== Total: 2
Order [oid=1, userId=2, orderNumber=20180810001, user=User [userid=2, userName=阿柯, pwd=123456, age=10, sex=女, birthday=Tue Aug 14 13:45:34 CST 2018], details=[Detail [detailId=1, orderId=1, productId=1, price=8888.0, status=1, product=Product [pid=1, pname=iphone8, price=8888.0, proDetail=蘋果公司最新產品]], Detail [detailId=2, orderId=1, productId=2, price=188.0, status=1, product=Product [pid=2, pname=冰峰戰神, price=188.0, proDetail=關羽騷氣皮膚]]]]
DEBUG - Resetting autocommit to true on JDBC Connection [oracle.jdbc.driver.T4CConnection@1b97680c]
DEBUG - Closing JDBC Connection [oracle.jdbc.driver.T4CConnection@1b97680c]
DEBUG - Returned connection 462907404 to pool.
1.6、resultMap的繼承
resultMap元素可以通過繼承機制來減少冗余
<resultMap type="Order" id="OrderResultMap" autoMapping="true">
<id column="oid" property="oid"/>
<!--
關聯的對象屬性
property：屬性名
javaType:這個屬性屬於什麽類型
autoMapping：自動映射
-->
<association property="user" javaType="User" autoMapping="true">
<id column="userid" property="userid"/>
</association>
</resultMap>
<resultMap type="Order" id="OrderResultMap2" autoMapping="true" extends="OrderResultMap">
<!--
配置多的一方使用collection這個節點
property:集合的屬性名稱
javaType：類型
ofType:集合中元素的類型
-->
<collection property="details" javaType="list" ofType="Detail" autoMapping="true">
<id column="detail_id" property="detailId"/>
</collection>
</resultMap>
<resultMap type="Order" id="OrderResultMap3" autoMapping="true" extends="OrderResultMap">
<!--
配置多的一方使用collection這個節點
property:集合的屬性名稱
javaType：類型
ofType:集合中元素的類型
-->
<collection property="details" javaType="list" ofType="Detail" autoMapping="true">
<id column="detail_id" property="detailId"/>
<association property="product" javaType="Product" autoMapping="true">
<id column="pid" property="pid"/>
</association>
</collection>
</resultMap>然後測試，運行ok
MyBatis學習（七）