xml 配置方式实现复杂映射回顾
实现复杂映射我们之前可以在映射文件中通过配置来实现，使用注解开发后，我们可以通过 @Results 注解，@Result 注解，@One 注解和 @Many 注解组合完成复杂关系的配置。
| 注解 | 说明 |
|---|---|
| @Results | 代替的是标签 ，该注解中可以使用单个的 @Result 注解，也可以使用 @Result 集合。 使用方式： @Results({@Result(), @Result()}) 或者 @Results(@Result()) |
| @Result | 代替了 标签和 标签 @Result 中的属性介绍 column：数据库中的列名 property：要装配的属性名 one：需要使用 @One 注解（ @Result(one=@One)() ） many：需要使用 @Many 注解（ @Result(many=@many)() ） |
| @One（一对一） | 代替了 标签，是多表查询的关键，在注解中用来指定子查询返回单一对象。 @One 注解属性介绍 select：指定用来多表查询的 sqlmapper 使用格式： @Result(column="", property="", one=(select="")) |
| @Many（多对一） | 代替了 标签，是多表查询的关键，在注解中用来指定子查询返回对象集合。 使用格式： @Result(property="", column="", many=@many(select="")) |
一对一查询
一对一查询的模型
用户表和订单表的关系为，一个用户有多个订单，一共订单只属于一个用户
一对一查询需求：查询一个订单，与此同时查询该订单对应的用户
@startuml !include https://unpkg.com/plantuml-style-c4@latest/core.puml ' uncomment the following line and comment the first to use locally '!include core.puml left to right direction class orders { ordertime: varchar(255) total: double uid: int(11) id: int(11) } class user { username: varchar(50) password: varchar(50) birthday: varchar(50) id: int(11) } orders -[#595959,plain]-^ user : "uid:id" @enduml
一对一查询的语句
对应的 sql 语句
select * from orders;
select * from user where id=查询出订单的uid;
查询结果如下：
| id | ordertime | total | uid | id | username | password | birthday |
|---|---|---|---|---|---|---|---|
| 1 | 2019-12-12 | 3000 | 1 | 1 | lucy | 123 | 2019-12-12 |
| 2 | 2019-12-12 | 4000 | 1 | 1 | lucy | 123 | 2019-12-12 |
| 3 | 2019-12-12 | 5000 | 2 | 1 | lucy | 123 | 2019-12-12 |
| 1 | 2019-12-12 | 3000 | 1 | 2 | tom | 123 | 2019-12-12 |
创建 User 和 Order 实体
/*** 订单** @name: Order* @author: terwer* @date: 2022-03-17 17:42**/
public class Order {private Integer id;private String orderTime;private Double total;// 代表当前订单属于哪一个用户private User user;public Integer getId() {return id;}public void setId(Integer id) {this.id = id;}public String getOrderTime() {return orderTime;}public void setOrderTime(String orderTime) {this.orderTime = orderTime;}public Double getTotal() {return total;}public void setTotal(Double total) {this.total = total;}public User getUser() {return user;}public void setUser(User user) {this.user = user;}@Overridepublic String toString() {return "Order{" +"id=" + id +", orderTime='" + orderTime + '\'' +", total=" + total +", user=" + user +'}';}
}/*** 用户** @name: User* @author: terwer* @date: 2022-05-25 13:25**/
public class User {private Integer id;private String username;public Integer getId() {return id;}public void setId(Integer id) {this.id = id;}public String getUsername() {return username;}public void setUsername(String username) {this.username = username;}@Overridepublic String toString() {return "User{" +"id=" + id +", username='" + username + '\'' +'}';}
}
创建 IOrderMapper 接口
/*** 订单映射** @name: IUserMapper* @author: terwer* @date: 2022-03-17 17:54**/
public interface IOrderMapper {public List<Order> findOrderAndUser();
}
使用注解配置接口
/*** 订单映射** @name: IUserMapper* @author: terwer* @date: 2022-03-17 17:54**/
public interface IOrderMapper {/*** 查询订单同时查询订单所属用户** @return*/@Results({@Result(property = "id", column = "id"),@Result(property = "orderTime", column = "ordertime"),@Result(property = "total", column = "total"),@Result(property = "user", column = "uid", javaType = User.class, one = @One(select = "com.terwergreen.mapper.IUserMapper.findUserById"))})@Select("select * from orders")public List<Order> findOrderAndUser();
}
/** 用户映射** @name: IUserMapper* @author: terwer* @date: 2022-05-25 13:27**/
public interface IUserMapper {/*** 根据ID查询用户* @param id* @return*/@Select("select * from user where id=#{id}")User findUserById(Integer id);
}
测试结果
/*** 订单测试** @name: IOrderMapperTest* @author: terwer* @date: 2022-08-31 22:52**/
public class IOrderMapperTest {private IOrderMapper orderMapper;private SqlSession sqlSession;@Beforepublic void before() throws Exception {System.out.println("before...");InputStream resourceAsStream = Resources.getResourceAsStream("sqlMapConfig.xml");SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(resourceAsStream);sqlSession = sqlSessionFactory.openSession();// 这样也是可以的，这样的话后面就不用每次都设置了// sqlSession = sqlSessionFactory.openSession(true);orderMapper = sqlSession.getMapper(IOrderMapper.class);}@Testpublic void testFindOrder() throws Exception {List<Order> orderAndUser = orderMapper.findOrderAndUser();orderAndUser.forEach(order -> {System.out.println(order);});}
}
效果
Opening JDBC Connection
Created connection 2024453272.
Setting autocommit to false on JDBC Connection [com.mysql.cj.jdbc.ConnectionImpl@78aab498]
==> Preparing: select * from orders
==> Parameters:
<== Columns: id, ordertime, total, uid
<== Row: 1, 2019-12-12, 3000.0, 1
====> Preparing: select * from user where id=?
====> Parameters: 1(Integer)
<==== Columns: id, username, password, birthday
<==== Row: 1, lucy, 123, 2019-12-12
<==== Total: 1
<== Row: 2, 2019-12-12, 4000.0, 1
<== Row: 3, 2019-12-12, 5000.0, 2
====> Preparing: select * from user where id=?
====> Parameters: 2(Integer)
<==== Columns: id, username, password, birthday
<==== Row: 2, tom, 123, 2019-12-12
<==== Total: 1
<== Total: 3
Order{id=1, orderTime='2019-12-12', total=3000.0, user=User{id=1, username='lucy'}}
Order{id=2, orderTime='2019-12-12', total=4000.0, user=User{id=1, username='lucy'}}
Order{id=3, orderTime='2019-12-12', total=5000.0, user=User{id=2, username='tom'}}Process finished with exit code 0
调用过程分析
image-20220901002006366
一对多查询
一对多查询的模型
用户表和订单表的关系为，一个用户有多个订单，一个订单只从属于一个用户。
一对多查询需求：查询一个用户，与此同时查出该用户具有的订单。
@startuml !include https://unpkg.com/plantuml-style-c4@latest/core.puml ' uncomment the following line and comment the first to use locally '!include core.puml left to right direction class orders { ordertime: varchar(255) total: double uid: int(11) id: int(11) } class user { username: varchar(50) password: varchar(50) birthday: varchar(50) id: int(11) } orders -[#595959,plain]-^ user : "uid:id" @enduml
一对多查询语句
对应查询语句：
对应的 sql 语句
select * from user;
select * from orders where uid=查询出用户的id;
查询结果如下：
| id | ordertime | total | uid | id | username | password | birthday |
|---|---|---|---|---|---|---|---|
| 1 | 2019-12-12 | 3000 | 1 | 1 | lucy | 123 | 2019-12-12 |
| 2 | 2019-12-12 | 4000 | 1 | 1 | lucy | 123 | 2019-12-12 |
| 3 | 2019-12-12 | 5000 | 2 | 1 | lucy | 123 | 2019-12-12 |
| 1 | 2019-12-12 | 3000 | 1 | 2 | tom | 123 | 2019-12-12 |
修改 User 实体
/*** 订单** @name: Order* @author: terwer* @date: 2022-03-17 17:42**/
public class Order {private Integer id;private String orderTime;private Double total;// 代表当前订单属于哪一个用户private User user;public Integer getId() {return id;}public void setId(Integer id) {this.id = id;}public String getOrderTime() {return orderTime;}public void setOrderTime(String orderTime) {this.orderTime = orderTime;}public Double getTotal() {return total;}public void setTotal(Double total) {this.total = total;}public User getUser() {return user;}public void setUser(User user) {this.user = user;}@Overridepublic String toString() {return "Order{" +"id=" + id +", orderTime='" + orderTime + '\'' +", total=" + total +", user=" + user +'}';}
}
/*** 用户** @name: User* @author: terwer* @date: 2022-05-25 13:25**/
public class User {private Integer id;private String username;// 代表当前用户具备那些订单private List<Order> orderList;public Integer getId() {return id;}public void setId(Integer id) {this.id = id;}public String getUsername() {return username;}public void setUsername(String username) {this.username = username;}public List<Order> getOrderList() {return orderList;}public void setOrderList(List<Order> orderList) {this.orderList = orderList;}@Overridepublic String toString() {return "User{" +"id=" + id +", username='" + username + '\'' +", orderList=" + orderList +'}';}
}
创建 IUserMapper 接口
/*** 用户映射** @name: IUserMapper* @author: terwer* @date: 2022-05-25 13:27**/
public interface IUserMapper {/*** 查询用户和订单** @return*/List<User> findUserAndOrder();
}
使用注解配置 Mapper
/*** 用户映射** @name: IUserMapper* @author: terwer* @date: 2022-05-25 13:27**/
public interface IUserMapper {/*** 查询用户和订单** @return*/@Results({@Result(property = "id", column = "id"),@Result(property = "username", column = "username"),@Result(property = "orderList", column = "id", many = @Many(select = "com.terwergreen.mapper.IOrderMapper.findOrderByUid"), javaType = List.class)})@Select("select * from user")List<User> findUserAndOrder();
}
/*** 订单映射** @name: IUserMapper* @author: terwer* @date: 2022-03-17 17:54**/
public interface IOrderMapper {@Select("select * from orders where uid=#{uid}")public List<Order> findOrderByUid(Integer uid);
}
测试结果
public class IUserMapperTest {private IUserMapper userMapper;private SqlSession sqlSession;@Beforepublic void before() throws Exception {System.out.println("before...");InputStream resourceAsStream = Resources.getResourceAsStream("sqlMapConfig.xml");SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(resourceAsStream);sqlSession = sqlSessionFactory.openSession();// 这样也是可以的，这样的话后面就不用每次都设置了// sqlSession = sqlSessionFactory.openSession(true);userMapper = sqlSession.getMapper(IUserMapper.class);}@Testpublic void testGetUserOrders() {List<User> userAndOrder = userMapper.findUserAndOrder();userAndOrder.forEach(user -> {System.out.println(user);});}
}
结果如下：
Opening JDBC Connection
Created connection 98394724.
Setting autocommit to false on JDBC Connection [com.mysql.cj.jdbc.ConnectionImpl@5dd6264]
==> Preparing: select * from user
==> Parameters:
<== Columns: id, username, password, birthday
<== Row: 1, lucy, 123, 2019-12-12
====> Preparing: select * from orders where uid=?
====> Parameters: 1(Integer)
<==== Columns: id, ordertime, total, uid
<==== Row: 1, 2019-12-12, 3000.0, 1
<==== Row: 2, 2019-12-12, 4000.0, 1
<==== Total: 2
<== Row: 2, tom, 123, 2019-12-12
====> Preparing: select * from orders where uid=?
====> Parameters: 2(Integer)
<==== Columns: id, ordertime, total, uid
<==== Row: 3, 2019-12-12, 5000.0, 2
<==== Total: 1
<== Row: 8, 测试2, null, null
====> Preparing: select * from orders where uid=?
====> Parameters: 8(Integer)
<==== Total: 0
<== Row: 9, 测试3, null, null
====> Preparing: select * from orders where uid=?
====> Parameters: 9(Integer)
<==== Total: 0
<== Total: 4
User{id=1, username='lucy', orderList=[Order{id=1, orderTime='2019-12-12', total=3000.0, user=null}, Order{id=2, orderTime='2019-12-12', total=4000.0, user=null}]}
User{id=2, username='tom', orderList=[Order{id=3, orderTime='2019-12-12', total=5000.0, user=null}]}
User{id=8, username='测试2', orderList=[]}
User{id=9, username='测试3', orderList=[]}Process finished with exit code 0
多对多查询
多对多查询的模型
用户表和角色表的关系为，一个用户有多个角色，一个角色被多个用户使用。
@startuml !include https://unpkg.com/plantuml-style-c4@latest/core.puml ' uncomment the following line and comment the first to use locally '!include core.puml left to right direction class sys_role { rolename: varchar(255) roleDesc: varchar(255) id: int(11) } class sys_user_role { userid: int(11) roleid: int(11) } class user { username: varchar(50) password: varchar(50) birthday: varchar(50) id: int(11) } sys_user_role -[#595959,plain]-^ sys_role : "roleid:id" sys_user_role -[#595959,plain]-^ user : "userid:id" @enduml
多对多查询需求
查询用户的同时查询该用户对应的角色。
多对多查询的语句
select * from user;
select * from sys_role r,sys_user_role ur where r.id=ur.roleid and ur.userid=用户的id
查询结果如下：
| id | rolename | roleDesc | userid | roleid |
|---|---|---|---|---|
| 1 | CTO | CTO | 1 | 1 |
| 2 | CEO | CEO | 1 | 2 |
代码实现
-
创建 User 实体和 Role 实体
/*** 用户** @name: User* @author: terwer* @date: 2022-05-25 13:25**/ public class User {private Integer id;private String username;// 代表当前用户具备那些订单private List<Order> orderList;// 代表当前用户具备的那些角色private List<Role> roleList;public Integer getId() {return id;}public void setId(Integer id) {this.id = id;}public String getUsername() {return username;}public void setUsername(String username) {this.username = username;}public List<Order> getOrderList() {return orderList;}public void setOrderList(List<Order> orderList) {this.orderList = orderList;}public List<Role> getRoleList() {return roleList;}public void setRoleList(List<Role> roleList) {this.roleList = roleList;}@Overridepublic String toString() {return "User{" +"id=" + id +", username='" + username + '\'' +", orderList=" + orderList +", roleList=" + roleList +'}';} } -
创建 IRoleMapper
/*** 角色映射** @name: IRoleMapper* @author: terwer* @date: 2022-09-06 00:04**/ public interface IRoleMapper {@Select("select * from sys_role r,sys_user_role ur where r.id=ur.roleid and ur.userid=#{userId}")List<Role> findRolesByUserId(Integer userId); }/*** 角色** @name: Role* @author: terwer* @date: 2022-05-12 14:14**/ public class Role {private Integer id;private String rolename;@Overridepublic String toString() {return "Role{" +"id=" + id +", rolename='" + rolename + '\'' +'}';} } -
修改 IUserMapper
/*** 用户映射** @name: IUserMapper* @author: terwer* @date: 2022-05-25 13:27**/ public interface IUserMapper {@Results({@Result(property = "id", column = "id"),@Result(property = "username", column = "username"),@Result(property = "roleList", column = "id", javaType = List.class,many = @Many(select = "com.terwergreen.mapper.IRoleMapper.findRolesByUserId"))})@Select("select * from user")List<User> findUserAndRole(); } -
添加测试方法
public class IUserMapperTest {private IUserMapper userMapper;private SqlSession sqlSession;@Beforepublic void before() throws Exception {System.out.println("before...");InputStream resourceAsStream = Resources.getResourceAsStream("sqlMapConfig.xml");SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(resourceAsStream);sqlSession = sqlSessionFactory.openSession();// 这样也是可以的，这样的话后面就不用每次都设置了// sqlSession = sqlSessionFactory.openSession(true);userMapper = sqlSession.getMapper(IUserMapper.class);}@Testpublic void testFindUserAndRole() {userMapper.findUserAndRole().forEach(user -> {System.out.println(user);});} } -
效果如下
Setting autocommit to false on JDBC Connection [com.mysql.cj.jdbc.ConnectionImpl@51e5fc98] ==> Preparing: select * from user ==> Parameters: <== Columns: id, username, password, birthday <== Row: 1, lucy, 123, 2019-12-12 ====> Preparing: select * from sys_role r,sys_user_role ur where r.id=ur.roleid and ur.userid=? ====> Parameters: 1(Integer) <==== Columns: id, rolename, roleDesc, userid, roleid <==== Row: 1, CTO, CTO, 1, 1 <==== Row: 2, CEO, CEO, 1, 2 <==== Total: 2 <== Row: 2, tom, 123, 2019-12-12 ====> Preparing: select * from sys_role r,sys_user_role ur where r.id=ur.roleid and ur.userid=? ====> Parameters: 2(Integer) <==== Columns: id, rolename, roleDesc, userid, roleid <==== Row: 1, CTO, CTO, 2, 1 <==== Row: 2, CEO, CEO, 2, 2 <==== Total: 2 <== Row: 8, 测试2, null, null ====> Preparing: select * from sys_role r,sys_user_role ur where r.id=ur.roleid and ur.userid=? ====> Parameters: 8(Integer) <==== Total: 0 <== Row: 9, 测试3, null, null ====> Preparing: select * from sys_role r,sys_user_role ur where r.id=ur.roleid and ur.userid=? ====> Parameters: 9(Integer) <==== Total: 0 <== Total: 4 User{id=1, username='lucy', orderList=null, roleList=[Role{id=1, rolename='CTO'}, Role{id=2, rolename='CEO'}]} User{id=2, username='tom', orderList=null, roleList=[Role{id=1, rolename='CTO'}, Role{id=2, rolename='CEO'}]} User{id=8, username='测试2', orderList=null, roleList=[]} User{id=9, username='测试3', orderList=null, roleList=[]}Process finished with exit code 0
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2022-08-30 feat:初稿
