update 8.21

pom.xml

@@ -79,6 +79,12 @@
             <version>4.4.0</version>
         </dependency>
 
+        <!-- mybatis-plus -->
+        <dependency>
+            <groupId>com.baomidou</groupId>
+            <artifactId>mybatis-plus-spring-boot3-starter</artifactId>
+            <version>3.5.5</version>
+        </dependency>
 
     </dependencies>
 

src/main/java/com/example/practice/controller/UserController.java

@@ -2,8 +2,12 @@ package com.example.practice.controller;
 
 
 import com.example.practice.entity.User;
+import com.example.practice.exception.MoneyNotEnoughException;
 import com.example.practice.mapper.UserMapper;
+import com.example.practice.service.UserService;
+import com.example.practice.service.impl.UserServiceImpl;
 import jakarta.annotation.Resource;
+import org.springframework.transaction.annotation.Transactional;
 import org.springframework.web.bind.annotation.*;
 
 import java.util.List;
@@ -13,7 +17,25 @@ import java.util.List;
 public class UserController {
 
     @Resource
-    UserMapper userMapper;
+    private UserMapper userMapper;
+
+
+    @Resource
+    private UserService userService;
+
+
+    /**
+     * A->B转账
+     */
+    @Transactional // 多条DML语句要么同时执行成功，要么同时失败
+    @GetMapping("transfer")
+    public boolean transfer(@RequestParam String fromAccount,
+                            @RequestParam String toAccount,
+                            @RequestParam int money) {
+
+        return userService.transfer(fromAccount, toAccount, money);
+    }
+
 
     @GetMapping("/queryAll")
     public List<User> queryAll() {
@@ -50,6 +72,15 @@ public class UserController {
         return userMapper.selectOne(id);
     }
 
+    @GetMapping("pageQuery")
+    public List<User> pageQuery(@RequestParam int pageNum, @RequestParam int pageSize) {
+        int offset = (pageNum - 1) * pageSize;
+        return userMapper.pageQuery(pageSize, offset);
+    }
+
+
+
+
 
 
 }

src/main/java/com/example/practice/entity/User.java

@@ -1,6 +1,13 @@
 package com.example.practice.entity;
 
 
+import lombok.AllArgsConstructor;
+import lombok.Data;
+import lombok.NoArgsConstructor;
+
+@Data
+@NoArgsConstructor
+@AllArgsConstructor
 public class User {
 
     /**
@@ -38,85 +45,5 @@ public class User {
      */
     private Integer money;
 
-    @Override
-    public String toString() {
-        return "User{" +
-                "id=" + id +
-                ", nickName='" + nickName + '\'' +
-                ", phoneNumber='" + phoneNumber + '\'' +
-                ", userAccount='" + userAccount + '\'' +
-                ", userPassword='" + userPassword + '\'' +
-                ", userRole='" + userRole + '\'' +
-                ", money=" + money +
-                '}';
-    }
 
-    public Long getId() {
-        return id;
-    }
-
-    public void setId(Long id) {
-        this.id = id;
-    }
-
-    public String getNickName() {
-        return nickName;
-    }
-
-    public void setNickName(String nickName) {
-        this.nickName = nickName;
-    }
-
-    public String getPhoneNumber() {
-        return phoneNumber;
-    }
-
-    public void setPhoneNumber(String phoneNumber) {
-        this.phoneNumber = phoneNumber;
-    }
-
-    public String getUserAccount() {
-        return userAccount;
-    }
-
-    public void setUserAccount(String userAccount) {
-        this.userAccount = userAccount;
-    }
-
-    public String getUserPassword() {
-        return userPassword;
-    }
-
-    public void setUserPassword(String userPassword) {
-        this.userPassword = userPassword;
-    }
-
-    public String getUserRole() {
-        return userRole;
-    }
-
-    public void setUserRole(String userRole) {
-        this.userRole = userRole;
-    }
-
-    public Integer getMoney() {
-        return money;
-    }
-
-    public void setMoney(Integer money) {
-        this.money = money;
-    }
-
-    public User(Long id, String nickName, String phoneNumber, String userAccount, String userPassword, String userRole, Integer money) {
-        this.id = id;
-        this.nickName = nickName;
-        this.phoneNumber = phoneNumber;
-        this.userAccount = userAccount;
-        this.userPassword = userPassword;
-        this.userRole = userRole;
-        this.money = money;
-    }
-
-    public User() {
-    }
 }

src/main/java/com/example/practice/exception/MoneyNotEnoughException.java

@@ -0,0 +1,9 @@
+package com.example.practice.exception;
+
+public class MoneyNotEnoughException extends RuntimeException {
+
+    public MoneyNotEnoughException() {
+        super("余额不足");
+    }
+
+}

src/main/java/com/example/practice/mapper/UserMapper.java

@@ -1,12 +1,13 @@
 package com.example.practice.mapper;
 
+import com.baomidou.mybatisplus.core.mapper.BaseMapper;
 import com.example.practice.entity.User;
 import org.apache.ibatis.annotations.Mapper;
 
 import java.util.List;
 
 @Mapper // 生成当前UserMapper接口的实现类对象，并且把这个对象放到SpringIOC 容器中
-public interface UserMapper {
+public interface UserMapper extends BaseMapper<User> {
 
     List<User> selectAll();
 
@@ -18,5 +19,8 @@ public interface UserMapper {
 
     int delete(Long id);
 
+    List<User> pageQuery(int pageSize, int offset);
+
+    User selectByAccount(String userAccount);
 }
 

src/main/java/com/example/practice/service/UserService.java

@@ -0,0 +1,10 @@
+package com.example.practice.service;
+
+public interface UserService {
+
+    /**
+     * 转账功能
+     */
+    boolean transfer(String fromAccount, String toAccount, int money);
+
+}

src/main/java/com/example/practice/service/impl/UserServiceImpl.java

@@ -0,0 +1,34 @@
+package com.example.practice.service.impl;
+
+import com.example.practice.entity.User;
+import com.example.practice.exception.MoneyNotEnoughException;
+import com.example.practice.mapper.UserMapper;
+import com.example.practice.service.UserService;
+import jakarta.annotation.Resource;
+import org.springframework.stereotype.Service;
+
+@Service
+public class UserServiceImpl implements UserService {
+
+    @Resource
+    private UserMapper userMapper;
+
+    @Override
+    public boolean transfer(String fromAccount, String toAccount, int money) {
+        User fromUser = userMapper.selectByAccount(fromAccount);
+        Integer fromAccountMoney = fromUser.getMoney();
+        if (money > fromAccountMoney) throw new MoneyNotEnoughException();
+
+        // 更新转出账户的余额
+        fromUser.setMoney(fromAccountMoney - money);
+        userMapper.update(fromUser);
+
+        User toUser = userMapper.selectByAccount(toAccount);
+        Integer toUserMoney = toUser.getMoney();
+
+        // 跟新转入账户的余额
+        toUser.setMoney(toUserMoney + money);
+        userMapper.update(toUser);
+        return true;
+    }
+}

src/main/resources/application.yml

@@ -8,3 +8,7 @@ spring:
 
 mybatis:
   mapper-locations: classpath:mapper/*.xml
+
+
+server:
+  port: 9090

src/main/resources/mapper/UserMapper.xml

@@ -23,7 +23,13 @@
         update user set nickName = #{nickName}, phoneNumber = #{phoneNumber}, userAccount = #{userAccount}, userPassword = #{userPassword}, userRole = #{userRole}, money = #{money} where id = #{id}
     </update>
 
+    <select id="pageQuery" resultType="com.example.practice.entity.User">
+        select * from user limit #{pageSize} offset #{offset}
+    </select>
 
+    <select id="selectByAccount" resultType="com.example.practice.entity.User">
+        select * from user where userAccount = #{userAccount}
+    </select>
 </mapper>
 
         <!--SQL映射文件-->