MyBatis高级映射查询
Posted zhangjinru123
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一、数据库数据和项目搭建过程
1、主要要四张表，分别为user用户信息表、items商品表、orderdetail订单明细表、orders订单表。表的结构和数据如下：
表结构
CREATE DATABASE mybatis DEFAULT CHARACTER SET utf8 COLLATE utf8_general_ci CREATE TABLE `items` ( `id` INT(11) NOT NULL AUTO_INCREMENT, `name` VARCHAR(32) NOT NULL COMMENT \'商品名称\', `price` FLOAT(10,1) NOT NULL COMMENT \'商品定价\', `detail` TEXT COMMENT \'商品描述\', `pic` VARCHAR(64) DEFAULT NULL COMMENT \'商品图片\', `createtime` DATETIME NOT NULL COMMENT \'生产日期\', PRIMARY KEY (`id`) ) ENGINE=INNODB AUTO_INCREMENT=4 DEFAULT CHARSET=utf8; CREATE TABLE `orderdetail` ( `id` INT(11) NOT NULL AUTO_INCREMENT, `orders_id` INT(11) NOT NULL COMMENT \'订单id\', `items_id` INT(11) NOT NULL COMMENT \'商品id\', `items_num` INT(11) DEFAULT NULL COMMENT \'商品购买数量\', PRIMARY KEY (`id`), KEY `FK_orderdetail_1` (`orders_id`), KEY `FK_orderdetail_2` (`items_id`), CONSTRAINT `FK_orderdetail_1` FOREIGN KEY (`orders_id`) REFERENCES `orders` (`id`) ON DELETE NO ACTION ON UPDATE NO ACTION, CONSTRAINT `FK_orderdetail_2` FOREIGN KEY (`items_id`) REFERENCES `items` (`id`) ON DELETE NO ACTION ON UPDATE NO ACTION ) ENGINE=INNODB AUTO_INCREMENT=5 DEFAULT CHARSET=utf8; CREATE TABLE `orders` ( `id` INT(11) NOT NULL AUTO_INCREMENT, `user_id` INT(11) NOT NULL COMMENT \'下单用户id\', `number` VARCHAR(32) NOT NULL COMMENT \'订单号\', `createtime` DATETIME NOT NULL COMMENT \'创建订单时间\', `note` VARCHAR(100) DEFAULT NULL COMMENT \'备注\', PRIMARY KEY (`id`), KEY `FK_orders_1` (`user_id`), CONSTRAINT `FK_orders_id` FOREIGN KEY (`user_id`) REFERENCES `user` (`id`) ON DELETE NO ACTION ON UPDATE NO ACTION ) ENGINE=INNODB AUTO_INCREMENT=6 DEFAULT CHARSET=utf8; CREATE TABLE `user` ( `id` INT(11) NOT NULL AUTO_INCREMENT, `username` VARCHAR(32) NOT NULL COMMENT \'用户名称\', `birthday` DATE DEFAULT NULL COMMENT \'生日\', `sex` CHAR(1) DEFAULT NULL COMMENT \'性别\', `address` VARCHAR(256) DEFAULT NULL COMMENT \'地址\', PRIMARY KEY (`id`) ) ENGINE=INNODB AUTO_INCREMENT=27 DEFAULT CHARSET=utf8;
表数据
INSERT INTO `items`(`id`,`name`,`price`,`detail`,`pic`,`createtime`) VALUES (1,\'台式机\',3000.0,\'该电脑质量非常好！！！！\',NULL,\'2015-02-03 13:22:53\'),(2,\'笔记本\',6000.0,\'笔记本性能好，质量好！！！！！\',NULL,\'2015-02-09 13:22:57\'),(3,\'背包\',200.0,\'名牌背包，容量大质量好！！！！\',NULL,\'2015-02-06 13:23:02\'); INSERT INTO `orderdetail`(`id`,`orders_id`,`items_id`,`items_num`) VALUES (1,3,1,1),(2,3,2,3),(3,4,3,4),(4,4,2,3); INSERT INTO `orders`(`id`,`user_id`,`number`,`createtime`,`note`) VALUES (3,1,\'1000010\',\'2015-02-04 13:22:35\',NULL),(4,1,\'1000011\',\'2015-02-03 13:22:41\',NULL),(5,10,\'1000012\',\'2015-02-12 16:13:23\',NULL); INSERT INTO `user`(`id`,`username`,`birthday`,`sex`,`address`) VALUES (1,\'王五\',NULL,\'2\',NULL),(10,\'张三\',\'2014-07-10\',\'1\',\'北京市\'),(16,\'张小明\',NULL,\'1\',\'河南郑州\'),(22,\'陈小明\',NULL,\'1\',\'河南郑州\'),(24,\'张三丰\',NULL,\'1\',\'河南郑州\'),(25,\'陈小明\',NULL,\'1\',\'河南郑州\'),(26,\'王五\',NULL,NULL,NULL);
2、整个项目的目录结构
3、首先创建mybatis配置文件SqlMapConfig.xml
1 <?xml version="1.0" encoding="UTF-8" ?> 2 <!DOCTYPE configuration 3 PUBLIC "-//mybatis.org//DTD Config 3.0//EN" 4 "http://mybatis.org/dtd/mybatis-3-config.dtd"> 5 <configuration> 6 <!-- 加载属性文件 --> 7 <properties resource="db.properties"> 8 9 </properties> 10 11 <!-- 和spring整合后 environments配置将废除--> 12 <environments default="development"> 13 <environment id="development"> 14 <!-- 使用jdbc事务管理，事务控制由mybatis--> 15 <transactionManager type="JDBC" /> 16 <!-- 数据库连接池，由mybatis管理--> 17 <dataSource type="POOLED"> 18 <property name="driver" value="${jdbc.driver}" /> 19 <property name="url" value="${jdbc.url}" /> 20 <property name="username" value="${jdbc.username}" /> 21 <property name="password" value="${jdbc.password}" /> 22 </dataSource> 23 </environment> 24 </environments> 25 26 <mappers> 27 <mapper resource="sqlmap/Orders.xml" /> 28 </mappers> 29 </configuration>
4、创建数据库配置文件db.properties
jdbc.driver=com.mysql.jdbc.Driver jdbc.url=jdbc:mysql://localhost:3306/mybatis?characterEncoding=utf-8 jdbc.username=root jdbc.password=123
5、创建映射文件orders.xml文件
1 <?xml version="1.0" encoding="UTF-8" ?> 2 <!DOCTYPE mapper 3 PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" 4 "http://mybatis.org/dtd/mybatis-3-mapper.dtd"> 5 6 <mapper namespace="com.zhang.dao.OrdersDao"> 7 8 <select id="findOrdersUser" resultType="com.zhang.domain.OrdersCustom"> 9 SELECT orders.*, USER.username,USER.sex,USER.address FROM orders,USER WHERE 10 orders.user_id = user.id 11 </select> 12 13 <resultMap type="com.zhang.domain.Orders" id="OrdersUserResultMap"> 14 <id column="id" property="id"/> 15 <result column="user_id" property="userId"/> 16 <result column="number" property="number"/> 17 <result column="createtime" property="createtime"/> 18 <result column="note" property="note"/> 19 20 <association property="user" javaType="com.zhang.domain.User"> 21 <id column="user_id" property="id"/> 22 <result column="username" property="username"/> 23 <result column="sex" property="sex"/> 24 <result column="address" property="address"/> 25 </association> 26 </resultMap> 27 <select id="findOrdersUserResultMap" resultMap="OrdersUserResultMap"> 28 SELECT orders.*, USER.username,USER.sex,USER.address FROM orders,USER WHERE 29 orders.user_id = user.id 30 </select> 31 32 <resultMap type="com.zhang.domain.Orders" id="OrdersAndOrderDetailResultMap" extends="OrdersUserResultMap" > 33 34 <collection property="orderdetails" ofType="com.zhang.domain.Orderdetail"> 35 <id column="orderdetail_id" property="id"/> 36 <result column="items_id" property="itemsId"/> 37 <result column="items_num" property="itemsNum"/> 38 <result column="orders_id" property="ordersId"/> 39 </collection> 40 </resultMap> 41 42 <!-- 查询订单关联查询用户及订单明细，使用resultmap --> 43 <select id="findOrdersAndOrderDetailResultMap" resultMap="OrdersAndOrderDetailResultMap"> 44 SELECT 45 orders.*, 46 USER.username, 47 USER.sex, 48 USER.address, 49 orderdetail.id orderdetail_id, 50 orderdetail.items_id, 51 orderdetail.items_num, 52 orderdetail.orders_id 53 FROM 54 orders, 55 USER, 56 orderdetail 57 WHERE orders.user_id = user.id AND orderdetail.orders_id=orders.id 58 </select> 59 60 <!-- 查询用户及购买的商品 --> 61 <resultMap type="com.zhang.domain.User" id="UserAndItemsResultMap"> 62 <!-- 用户信息 --> 63 <id column="user_id" property="id"/> 64 <result column="username" property="username"/> 65 <result column="sex" property="sex"/> 66 <result column="address" property="address"/> 67 <!-- 订单信息一个用户对应多个订单，使用collection映射--> 68 <collection property="ordersList" ofType="com.zhang.domain.Orders"> 69 <id column="id" property="id"/> 70 <result column="user_id" property="userId"/> 71 <result column="number" property="number"/> 72 <result column="createtime" property="createtime"/> 73 <result column="note" property="note"/> 74 <!-- 订单明细 一个订单包括 多个明细--> 75 <collection property="orderdetails" ofType="com.zhang.domain.Orderdetail"> 76 <id column="orderdetail_id" property="id"/> 77 <result column="items_id" property="itemsId"/> 78 <result column="items_num" property="itemsNum"/> 79 <result column="orders_id" property="ordersId"/> 80 <!-- 商品信息一个订单明细对应一个商品--> 81 <association property="items" javaType="com.zhang.domain.Items"> 82 <id column="items_id" property="id"/> 83 <result column="items_name" property="name"/> 84 <result column="items_detail" property="detail"/> 85 <result column="items_price" property="price"/> 86 </association> 87 </collection> 88 </collection> 89 </resultMap> 90 91 <!-- 查询用户及购买的商品信息，使用resultmap --> 92 <select id="findUserAndItemsResultMap" resultMap="UserAndItemsResultMap"> 93 SELECT 94 orders.*, 95 USER.username, 96 USER.sex, 97 USER.address, 98 orderdetail.id orderdetail_id, 99 orderdetail.items_id, 100 orderdetail.items_num, 101 orderdetail.orders_id, 102 items.name items_name, 103 items.detail items_detail, 104 items.price items_price 105 FROM 106 orders, 107 USER, 108 orderdetail, 109 items 110 WHERE orders.user_id = user.id AND orderdetail.orders_id=orders.id AND orderdetail.items_id = items.id 111 </select> 112 </mapper>
6、创建接口类OrderDao.java
1 package com.zhang.dao; 2 3 import java.util.List; 4 5 import com.zhang.domain.Orders; 6 import com.zhang.domain.OrdersCustom; 7 import com.zhang.domain.User; 8 public interface OrdersDao { 9 10 //查询订单关联查询用户信息 11 public List<OrdersCustom> findOrdersUser()throws Exception; 12 13 //查询订单关联查询用户使用resultMap 14 public List<Orders> findOrdersUserResultMap()throws Exception; 15 16 //查询订单(关联用户)及订单明细 17 public List<Orders> findOrdersAndOrderDetailResultMap()throws Exception; 18 19 //查询用户购买商品信息 20 public List<User> findUserAndItemsResultMap()throws Exception; 21 22 //查询订单关联查询用户，用户信息是延迟加载 23 public List<Orders> findOrdersUserLazyLoading()throws Exception; 24 }
7、创建各种实体类user、orders、items、ordersdetail类
user类
1 package com.zhang.domain; 2 3 import java.io.Serializable; 4 import java.util.Date; 5 import java.util.List; 6 7 8 public class User implements Serializable { 9 10 //属性名和数据库表的字段对应 11 private int id; 12 private String username;// 用户姓名 13 private String sex;// 性别 14 private Date birthday;// 生日 15 private String address;// 地址 16 17 //用户创建的订单列表 18 private List<Orders> ordersList; 19 20 21 public int getId() { 22 return id; 23 } 24 public void setId(int id) { 25 this.id = id; 26 } 27 public String getUsername() { 28 return username; 29 } 30 public void setUsername(String username) { 31 this.username = username; 32 } 33 public String getSex() { 34 return sex; 35 } 36 public void setSex(String sex) { 37 this.sex = sex; 38 } 39 public Date getBirthday() { 40 return birthday; 41 } 42 public void setBirthday(Date birthday) { 43 this.birthday = birthday; 44 } 45 public String getAddress() { 46 return address; 47 } 48 public void setAddress(String address) { 49 this.address = address; 50 } 51 @Override 52 public String toString() { 53 return "User [id=" + id + ", username=" + username + ", sex=" + sex 54 + ", birthday=" + birthday + ", address=" + address + "]"; 55 } 56 public List<Orders> getOrdersList() { 57 return ordersList; 58 } 59 public void setOrdersList(List<Orders> ordersList) { 60 this.ordersList = ordersList; 61 } 62 63 64 }
orders类
1 package com.zhang.domain; 2 3 import java.util.Date; 4 import java.util.List; 5 6 public class Orders { 7 private Integer id; 8 9 private Integer userId; 10 11 private String number; 12 13 private Date createtime; 14 15 private String note; 16 17 //用户信息 18 private User user; 19 20 //订单明细 21 private List<Orderdetail> orderdetails; 22 23 public Integer getId() { 24 return id; 25 } 26 27 public void setId(Integer id) { 28 this.id = id; 29 } 30 31 public Integer getUserId() { 32 return userId; 33 } 34 35 public void setUserId(Integer userId) { 36 this.userId = userId; 37 } 38 39 public String getNumber() { 40 return number; 41 } 42 43 public void setNumber(String number) { 44 this.number = number == null ? null : number.trim(); 45以上是关于MyBatis高级映射查询的主要内容，如果未能解决你的问题，请参考以下文章