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 }
46
47 public Date getCreatetime() {
48 return createtime;
49 }
50
51 public void setCreatetime(Date createtime) {
52 this.createtime = createtime;
53 }
54
55 public String getNote() {
56 return note;
57 }
58
59 public void setNote(String note) {
60 this.note = note == null ? null : note.trim();
61 }
62
63 public User getUser() {
64 return user;
65 }
66
67 public void setUser(User user) {
68 this.user = user;
69 }
70
71 public List<Orderdetail> getOrderdetails() {
72 return orderdetails;
73 }
74
75 public void setOrderdetails(List<Orderdetail> orderdetails) {
76 this.orderdetails = orderdetails;
77 }
78
79
80
81
82 }
l
items类
1 package com.zhang.domain;
2
3 import java.util.Date;
4
5 public class Items {
6 private Integer id;
7
8 private String name;
9
10 private Float price;
11
12 private String pic;
13
14 private Date createtime;
15
16 private String detail;
17
18 public Integer getId() {
19 return id;
20 }
21
22 public void setId(Integer id) {
23 this.id = id;
24 }
25
26 public String getName() {
27 return name;
28 }
29
30 public void setName(String name) {
31 this.name = name == null ? null : name.trim();
32 }
33
34 public Float getPrice() {
35 return price;
36 }
37
38 public void setPrice(Float price) {
39 this.price = price;
40 }
41
42 public String getPic() {
43 return pic;
44 }
45
46 public void setPic(String pic) {
47 this.pic = pic == null ? null : pic.trim();
48 }
49
50 public Date getCreatetime() {
51 return createtime;
52 }
53
54 public void setCreatetime(Date createtime) {
55 this.createtime = createtime;
56 }
57
58 public String getDetail() {
59 return detail;
60 }
61
62 public void setDetail(String detail) {
63 this.detail = detail == null ? null : detail.trim();
64 }
65
66 @Override
67 public String toString() {
68 return "Items [id=" + id + ", name=" + name + ", price=" + price
69 + ", pic=" + pic + ", createtime=" + createtime + ", detail="
70 + detail + "]";
71 }
72
73 }
orderdetail类
1 package com.zhang.domain;
2
3 public class Orderdetail {
4 private Integer id;
5
6 private Integer ordersId;
7
8 private Integer itemsId;
9
10 private Integer itemsNum;
11
12 //明细对应的商品信息
13 private Items items;
14
15
16 public Integer getId() {
17 return id;
18 }
19
20 public void setId(Integer id) {
21 this.id = id;
22 }
23
24 public Integer getOrdersId() {
25 return ordersId;
26 }
27
28 public void setOrdersId(Integer ordersId) {
29 this.ordersId = ordersId;
30 }
31
32 public Integer getItemsId() {
33 return itemsId;
34 }
35
36 public void setItemsId(Integer itemsId) {
37 this.itemsId = itemsId;
38 }
39
40 public Integer getItemsNum() {
41 return itemsNum;
42 }
43
44 public void setItemsNum(Integer itemsNum) {
45 this.itemsNum = itemsNum;
46 }
47
48 public Items getItems() {
49 return items;
50 }
51
52 public void setItems(Items items) {
53 this.items = items;
54 }
55
56 @Override
57 public String toString() {
58 return "Orderdetail [id=" + id + ", ordersId=" + ordersId
59 + ", itemsId=" + itemsId + ", itemsNum=" + itemsNum + "]";
60 }
61
62 }
8、创建测试类TestMy.java
1 package com.zhang.test;
2
3 import java.io.InputStream;
4 import java.util.List;
5
6 import org.apache.ibatis.io.Resources;
7 import org.apache.ibatis.session.SqlSession;
8 import org.apache.ibatis.session.SqlSessionFactory;
9 import org.apache.ibatis.session.SqlSessionFactoryBuilder;
10 import org.junit.Before;
11 import org.junit.Test;
12
13 import com.zhang.dao.OrdersDao;
14 import com.zhang.domain.Orders;
15 import com.zhang.domain.OrdersCustom;
16 import com.zhang.domain.User;
17
18 public class TestMy {
19 private SqlSessionFactory sqlSessionFactory;
20
21 // 此方法是在执行testFindUserById之前执行
22 @Before
23 public void setUp() throws Exception {
24 // 创建sqlSessionFactory
25 // mybatis配置文件
26 String resource = "SqlMapConfig.xml";
27 // 得到配置文件流
28 InputStream inputStream = Resources.getResourceAsStream(resource);
29 // 创建会话工厂，传入mybatis的配置文件信息
30 sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
31 }
32
33
34 //一对一查询利用resultType
35 @Test
36 public void findOrdersUser() throws Exception {
37 SqlSession sqlSession = sqlSessionFactory.openSession();
38 OrdersDao ordersDao = sqlSession.getMapper(OrdersDao.class);
39 List<OrdersCustom> list=ordersDao.findOrdersUser();
40 System.out.println(list.size());
41 }
42
43 //一对一查询利用resultMap
44 @Test
45 public void findOrdersUserResultMap() throws Exception {
46 SqlSession sqlSession = sqlSessionFactory.openSession();
47 OrdersDao ordersDao = sqlSession.getMapper(OrdersDao.class);
48 List<Orders> list=ordersDao.findOrdersUserResultMap();
49 System.out.println(list.size());
50 }
51
52 //一对多查询
53 @Test
54 public void findOrdersAndOrderDetailResultMap() throws Exception {
55 SqlSession sqlSession = sqlSessionFactory.openSession();
56 OrdersDao ordersDao = sqlSession.getMapper(OrdersDao.class);
57 List<Orders> list=ordersDao.findOrdersAndOrderDetailResultMap();
58 System.out.println(list.size());
59 }
60
61 //多对多查询
62 @Test
63 public void findUserAndItemsResultMap() throws Exception {
64 SqlSession sqlSession = sqlSessionFactory.openSession();
65 OrdersDao ordersDao = sqlSession.getMapper(OrdersDao.class);
66 List<User> list=ordersDao.findUserAndItemsResultMap();
67 System.out.println(list.size());
68 }
69
70 }
二、一对一高级查询
1.需求:查询订单信息，关联查询创建订单的用户信息
2. 利用 resultType映射查询，创建pojo类继承Orders类
1 package com.zhang.domain;
2
3 //通过此类映射订单和用户查询的结果，让此类继承包括 字段较多的pojo类
4 public class OrdersCustom extends Orders{
5
6 //添加用户属性
7 private String username;
8 private String sex;
9 private String address;
10
11
12 public String getUsername() {
13 return username;
14 }
15 public void setUsername(String username) {
16 this.username = username;
17 }
18 public String getSex() {
19 return sex;
20 }
21 public void setSex(String sex) {
22 this.sex = sex;
23 }
24 public String getAddress() {
25 return address;
26 }
27 public void setAddress(String address) {
28 this.address = address;
29 }
30
31
32
33 }
3、编写findOrdersUser接口
4、在Orders.xml文件定义SQL映射关系
5、测试方法：
6、利用resultMap映射查询，在Orders类中添加User属性：
7、编写接口方法
8、在Orders.xml中添加ResultMap信息：
9、测试方法：
三、一对多查询
1.需求：查询订单及订单明细的信息。
2.在Orders类中新增属性。
3、编写接口方法
4、在order.xml编写resultMap，继承上面的resultMap
5、测试方法
四、多对多查询
1.需求:查询用户及用户购买商品信息。
2.实现思路：
将用户信息映射到user中。
在user类中添加订单列表属性List<Orders> orderslist，将用户创建的订单映射到orderslist
3、在Orders中添加订单明细列表属性List<OrderDetail>orderdetials，将订单的明细映射到orderdetials
4、在OrderDetail中添加Items属性，将订单明细所对应的商品映射到Items
5、编写接口方法
6、测试方法
五、知识点总结
1、resultMap与resultType：
resultType： 将查询结果按照sql列名pojo属性名一致性映射到pojo中。
场合：常见一些明细记录的展示，比如用户购买商品明细，将关联查询信息全部展示在页面时，此时可直接使用resultType将每一条记录映射到pojo中，在前端页面遍历list（list中是pojo）即可。
resultMap：使用association和collection完成一对一和一对多高级映射（对结果有特殊的映射要求）。
2、association
作用： 将关联查询信息映射到一个pojo对象中。（一个对象）
场合：为了方便查询关联信息可以使用association将关联订单信息映射为用户对象的pojo属性中，比如：查询订单及关联用户信息。使用resultType无法将查询结果映射到pojo对象的pojo属性中，根据对结果集查询遍历的需要选择使用resultType还是resultMap。
3、collection
作用：将关联查询信息映射到一个list集合中。
场合：为了方便查询遍历关联信息可以使用collection将关联信息映射到list集合中，比如：查询用户权限范围模块及模块下的菜单，可使用collection将模块映射到模块list中，将菜单列表映射到模块对象的菜单list属性中，这样的作的目的也是方便对查询结果集进行遍历查询。
时间： 2024-10-05 03:10:03