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springboot2.0-统一处理返回结果和异常情况

一、统一处理返回结果和异常处理的原因：

1、在springboot项目里我们希望接口返回的数据包含至少三个属性：

a、code：请求接口的返回码，成功或者异常等返回编码，例如定义请求成功，code = "0000",查询结果为null，code = "0001";

b、msg：请求接口的描述，也就是对返回编码的描述，"0000"：就表示请求成功，"0001"：表示结果为null；

c、data：请求接口成功，返回的结果。

  1. {
  2.     "data": {
  3.         "id": 1,
  4.         "studentId": "13240115",
  5.         "name": "Tiger",
  6.         "age": 25,
  7.         "famillyAddress": "北京",
  8.         "createdDate": "2018-10-08T05:45:49.000+0000",
  9.         "updatedDate": "2018-10-09T03:15:33.000+0000"
  10.     },
  11.     "code": "0000",
  12.     "msg": "请求成功"
  13. }

2、在springboot项目里我们希望请求结果失败之后，通过返回码和返回描述来告诉前端接口请求异常。

  1. {
  2.     "code": "0001",
  3.     "msg": "学号不存在"
  4. }

二、案例

1、建一张学生信息表，包含学生的学号、姓名、年龄、家庭住址等

  1. CREATE TABLE student_info (
  2.   id bigint(20) NOT NULL AUTO_INCREMENT COMMENT '自增',
  3.   student_id varchar(20) NOT NULL COMMENT '学号',
  4.   name varchar(64) NOT NULL COMMENT '姓名',
  5.   age int(2) NOT NULL COMMENT '年龄',
  6.   familly_address varchar(256) NOT NULL COMMENT '家庭地址',
  7.   created_date datetime NOT NULL DEFAULT CURRENT_TIMESTAMP COMMENT '创建时间',
  8.   updated_date datetime NOT NULL DEFAULT CURRENT_TIMESTAMP COMMENT '更新时间',
  9.   PRIMARY KEY (student_id),
  10.   KEY id (id)
  11. ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4

2、pom.xml

  1. <dependencies>
  2.       <dependency>
  3.           <groupId>org.springframework.boot</groupId>
  4.             <artifactId>spring-boot-starter-web</artifactId>
  5.        </dependency>
  6.  
  7.      <dependency>
  8.           <groupId>org.springframework.boot</groupId>
  9.             <artifactId>spring-boot-starter-test</artifactId>
  10.          <scope>test</scope>
  11.        </dependency>
  12.  
  13.        <dependency>
  14.          <groupId>org.springframework.boot</groupId>
  15.            <artifactId>spring-boot-starter-data-redis</artifactId>
  16.        </dependency>
  17.  
  18.        <dependency>
  19.          <groupId>org.mybatis.spring.boot</groupId>
  20.             <artifactId>mybatis-spring-boot-starter</artifactId>
  21.           <version>1.3.1</version>
  22.       </dependency>
  23.  
  24.        <dependency>
  25.          <groupId>mysql</groupId>
  26.           <artifactId>mysql-connector-java</artifactId>
  27.          <version>5.1.46</version>
  28.      </dependency>
  29.  
  30.        <dependency>
  31.          <groupId>com.alibaba</groupId>
  32.             <artifactId>druid</artifactId>
  33.             <version>1.1.9</version>
  34.       </dependency>
  35.  
  36.        <dependency>
  37.          <groupId>org.projectlombok</groupId>
  38.           <artifactId>lombok</artifactId>
  39.            <version>1.16.22</version>
  40.         </dependency>
  41.  
  42.        <dependency>
  43.          <groupId>com.alibaba</groupId>
  44.             <artifactId>fastjson</artifactId>
  45.          <version>1.2.43</version>
  46.      </dependency>
  47.  
  48.  
  49.       <dependency>
  50.          <groupId>com.squareup.okhttp3</groupId>
  51.            <artifactId>okhttp</artifactId>
  52.            <version>3.9.1</version>
  53.       </dependency>
  54.  
  55.        <dependency>
  56.          <groupId>org.glassfish</groupId>
  57.           <artifactId>javax.json</artifactId>
  58.            <version>1.0.4</version>
  59.       </dependency>
  60.  
  61.        <dependency>
  62.          <groupId>org.apache.tomcat.embed</groupId>
  63.             <artifactId>tomcat-embed-jasper</artifactId>
  64.       </dependency>
  65.  
  66.    </dependencies>

3、案例中使用redis进行缓存，可以不需要

Windows环境安装redis以及缓存应用

4、创建实体类：StudentInfo

  1. package com.dl.cn.message.bean;
  2.  
  3. import lombok.AllArgsConstructor;
  4. import lombok.Builder;
  5. import lombok.Data;
  6. import lombok.NoArgsConstructor;
  7.  
  8. import java.io.Serializable;
  9. import java.util.Date;
  10.  
  11. /**
  12.  * Created by Tiger on 2018/10/8.
  13.  */
  14. @Data
  15. @Builder
  16. @AllArgsConstructor
  17. @NoArgsConstructor
  18. public class StudentInfo implements Serializable{
  19.  
  20.     private static final long serialVersionUID = 2597547944454691103L;
  21.  
  22.     private Long id;
  23.     private String studentId;
  24.     private String name;
  25.     private Integer age;
  26.     private String famillyAddress;
  27.     private Date createdDate;
  28.     private Date updatedDate;
  29. }

5、创建Mapper：StudentInfoMapper

  1. package com.dl.cn.message.mapper;
  2.  
  3. import com.dl.cn.message.bean.StudentInfo;
  4. import org.apache.ibatis.annotations.*;
  5.  
  6. /**
  7.  * Created by Tiger on 2018/10/8.
  8.  */
  9. @Mapper
  10. public interface StudentInfoMapper {
  11.     @Insert("insert into student_info(student_id,name,age,familly_address)" +
  12.             " values(#{studentId},#{name},#{age},#{famillyAddress})")
  13.     /**
  14.      * 通过bean保存实体类是，建议不要通过@Param注解，负责实体类的属性都在@Param中找
  15.      * */
  16.     void saveStudentInfo(StudentInfo studentInfo);
  17.  
  18.  
  19.     @Select("select * from student_info where student_id = #{studentId}")
  20.     StudentInfo findByStudentId(@Param("studentId") String studentId);
  21.  
  22.  
  23.     @Update("update student_info set familly_address = #{famillyAddress},updated_date = now() ")
  24.     void updateFamillyAddress(@Param("studentId") String studentId,@Param("famillyAddress") String famillyAddress);
  25. }

6、创建service：StudentInfoService

  1. package com.dl.cn.message.service;
  2.  
  3. import com.dl.cn.message.bean.StudentInfo;
  4. import com.dl.cn.message.mapper.StudentInfoMapper;
  5. import lombok.extern.slf4j.Slf4j;
  6. import org.springframework.beans.factory.annotation.Autowired;
  7. import org.springframework.cache.annotation.CacheConfig;
  8. import org.springframework.cache.annotation.CacheEvict;
  9. import org.springframework.cache.annotation.Cacheable;
  10. import org.springframework.stereotype.Service;
  11.  
  12. /**
  13.  * Created by Tiger on 2018/10/8.
  14.  */
  15. @Service
  16. @CacheConfig(cacheNames = "studentInfo")
  17. @Slf4j
  18. public class StudentInfoService {
  19.  
  20.     @Autowired
  21.     StudentInfoMapper studentInfoMapper;
  22.  
  23.     /**
  24.      * 保存学生信息
  25.      * @param studentInfo
  26.      * */
  27.     public void saveStudentInfo(StudentInfo studentInfo){
  28.         studentInfoMapper.saveStudentInfo(studentInfo);
  29.     }
  30.  
  31.     /**
  32.      * 根据学号查学生信息
  33.      * @param studentId
  34.      * @return
  35.      * */
  36.     @Cacheable(key = "#studentId",unless = "#result == null")
  37.     public StudentInfo findByStudentId(String studentId){
  38.         log.info("查找信息:{}",studentId);
  39.         return studentInfoMapper.findByStudentId(studentId);
  40.     }
  41.  
  42.     /**
  43.      * 根据学号更新家庭地址
  44.      * @param studentId
  45.      * @param famillyAddress
  46.      * */
  47.     //删除对应key的缓存
  48.     @CacheEvict(key = "#studentId")
  49.     public void updateFamillyAddress(String studentId,String famillyAddress){
  50.         studentInfoMapper.updateFamillyAddress(studentId,famillyAddress);
  51.     }
  52. }

7、创建统一返回结果类：Response

  1. package com.dl.cn.message.response;
  2.  
  3. import com.fasterxml.jackson.databind.annotation.JsonSerialize;
  4. import lombok.Getter;
  5. import lombok.Setter;
  6.  
  7. import java.io.Serializable;
  8.  
  9. /**
  10.  * 请求返回类
  11.  * Created by Tiger on 2018/10/9.
  12.  */
  13. @Getter
  14. @Setter
  15. @JsonSerialize(include= JsonSerialize.Inclusion.NON_NULL)
  16. public class Response<T> implements Serializable {
  17.  
  18.     private static final long serialVersionUID = -4505655308965878999L;
  19.  
  20.     //请求成功返回码为：0000
  21.     private static final String successCode = "0000";
  22.     //返回数据
  23.     private T data;
  24.     //返回码
  25.     private String code;
  26.     //返回描述
  27.     private String msg;
  28.  
  29.     public Response(){
  30.         this.code = successCode;
  31.         this.msg = "请求成功";
  32.     }
  33.  
  34.     public Response(String code,String msg){
  35.         this();
  36.         this.code = code;
  37.         this.msg = msg;
  38.     }
  39.     public Response(String code,String msg,T data){
  40.         this();
  41.         this.code = code;
  42.         this.msg = msg;
  43.         this.data = data;
  44.     }
  45.     public Response(T data){
  46.         this();
  47.         this.data = data;
  48.     }
  49. }

8、创建异常编码和描述类：ErrorCodeAndMsg

  1. package com.dl.cn.message.enums;
  2.  
  3. /**
  4.  * Created by Tiger on 2018/10/9.
  5.  */
  6. public enum  ErrorCodeAndMsg {
  7.  
  8.     Student_number_does_not_exist("0001","学号不存在"),
  9.     Insufficient_student_number("0002","学号长度不足"),
  10.     Student_number_is_empty("0003","学号为空"),
  11.     Network_error("9999","网络错误，待会重试"),
  12.     ;
  13.  
  14.     private String code;
  15.     private String msg;
  16.  
  17.     ErrorCodeAndMsg(String code, String msg) {
  18.         this.code = code;
  19.         this.msg = msg;
  20.     }
  21.  
  22.     public String getCode() {
  23.         return code;
  24.     }
  25.     public void setCode(String code) {
  26.         this.code = code;
  27.     }
  28.     public String getMsg() {
  29.         return msg;
  30.     }
  31.     public void setMsg(String msg) {
  32.         this.msg = msg;
  33.     }
  34. }

9、创建统一异常处理类：StudentException

  1. package com.dl.cn.message.exception;
  2.  
  3. import com.dl.cn.message.enums.ErrorCodeAndMsg;
  4.  
  5. import java.io.Serializable;
  6.  
  7. /**
  8.  * 统一异常捕获类
  9.  * Created by Tiger on 2018/10/9.
  10.  */
  11. public class StudentException extends RuntimeException{
  12.  
  13.     private static final long serialVersionUID = -6370612186038915645L;
  14.  
  15.     private final ErrorCodeAndMsg response;
  16.  
  17.     public StudentException(ErrorCodeAndMsg response) {
  18.         this.response = response;
  19.     }
  20.     public ErrorCodeAndMsg getResponse() {
  21.         return response;
  22.     }
  23. }

10、创建异常处理的全局配置类：ExceptionHandler

  1. package com.dl.cn.message.exception;
  2.  
  3. import com.dl.cn.message.enums.ErrorCodeAndMsg;
  4. import com.dl.cn.message.response.Response;
  5. import lombok.extern.slf4j.Slf4j;
  6. import org.springframework.web.bind.annotation.ControllerAdvice;
  7. import org.springframework.web.bind.annotation.ResponseBody;
  8.  
  9. import javax.servlet.http.HttpServletRequest;
  10.  
  11. /**
  12.  * Created by Tiger on 2018/10/9.
  13.  */
  14. @ControllerAdvice
  15. @Slf4j
  16. public class ExceptionHandler {
  17.     @org.springframework.web.bind.annotation.ExceptionHandler(StudentException.class)
  18.     @ResponseBody
  19.     public Response handleStudentException(HttpServletRequest request, StudentException ex) {
  20.         Response response;
  21.         log.error("StudentException code:{},msg:{}",ex.getResponse().getCode(),ex.getResponse().getMsg());
  22.         response = new Response(ex.getResponse().getCode(),ex.getResponse().getMsg());
  23.         return response;
  24.     }
  25.     @org.springframework.web.bind.annotation.ExceptionHandler(Exception.class)
  26.     @ResponseBody
  27.     public Response handleException(HttpServletRequest request, Exception ex) {
  28.         Response response;
  29.         log.error("exception error:{}",ex);
  30.         response = new Response(ErrorCodeAndMsg.Network_error.getCode(),
  31.                 ErrorCodeAndMsg.Network_error.getMsg());
  32.         return response;
  33.     }
  34. }

11、创建controler类：StudentInofController

  1. package com.dl.cn.message.controller;
  2.  
  3. import com.dl.cn.message.enums.ErrorCodeAndMsg;
  4. import com.dl.cn.message.exception.StudentException;
  5. import com.dl.cn.message.response.Response;
  6. import com.dl.cn.message.service.StudentInfoService;
  7. import com.dl.cn.message.bean.StudentInfo;
  8. import lombok.extern.slf4j.Slf4j;
  9. import org.springframework.beans.factory.annotation.Autowired;
  10. import org.springframework.web.bind.annotation.PostMapping;
  11. import org.springframework.web.bind.annotation.RequestMapping;
  12. import org.springframework.web.bind.annotation.RequestParam;
  13. import org.springframework.web.bind.annotation.RestController;
  14.  
  15. /**
  16.  * Created by Tiger on 2018/10/8.
  17.  */
  18. @RestController
  19. @RequestMapping("/student")
  20. @Slf4j
  21. public class StudentInofController {
  22.     @Autowired
  23.     StudentInfoService studentInfoService;
  24.  
  25.     /**
  26.      * 保存学生信息
  27.      * @param studentId
  28.      * @param name
  29.      * @param age
  30.      * @param famillyAddress
  31.      * */
  32.     @PostMapping("/save")
  33.     public void saveStudentInfo(@RequestParam("student_id") String studentId,
  34.                                 @RequestParam("name") String name,
  35.                                 @RequestParam("age") Integer age,
  36.                                 @RequestParam("familly_address") String famillyAddress){
  37.         StudentInfo studentInfo = StudentInfo.builder()
  38.                 .studentId(studentId)
  39.                 .name(name)
  40.                 .age(age)
  41.                 .famillyAddress(famillyAddress)
  42.                 .build();
  43.         studentInfoService.saveStudentInfo(studentInfo);
  44.     }
  45.  
  46.     /**
  47.      * 根据学号查学生信息
  48.      * @param studentId
  49.      * @return
  50.      * */
  51.     @PostMapping("/findByStudentId")
  52.     public Response findByStudentId(@RequestParam("student_id") String studentId){
  53.         try{
  54.             log.info("Get student information based on student number:{}",studentId);
  55.             if(studentId == null){
  56.                 throw new StudentException(ErrorCodeAndMsg.Student_number_is_empty);
  57.             }
  58.             //学号固定为8位
  59.             if(studentId.length() != 8){
  60.                 throw new StudentException(ErrorCodeAndMsg.Insufficient_student_number);
  61.             }
  62.             StudentInfo studentInfo = studentInfoService.findByStudentId(studentId);
  63.             if(studentInfo == null){
  64.                 throw new StudentException(ErrorCodeAndMsg.Student_number_does_not_exist);
  65.             }
  66.             return new Response(studentInfo);
  67.         }catch (Exception e){
  68.             if(e instanceof StudentException){
  69.                 throw e;
  70.             }else {
  71.                 log.error("findByStudentId error:",e);
  72.                 throw new StudentException(ErrorCodeAndMsg.Network_error);
  73.             }
  74.         }
  75.     }
  76.  
  77.     @PostMapping("/updateFamillyAddress")
  78.     public Response updateFamillyAddress(@RequestParam("student_id") String studentId,
  79.                                      @RequestParam("familly_address") String famillyAddress){
  80.         studentInfoService.updateFamillyAddress(studentId,famillyAddress);
  81.         Response response = new Response();
  82.         System.out.println(response.toString());
  83.         return response;
  84.     }
  85.  
  86.  
  87. }

12、application.properties配置

  1. #redis
  2. spring.redis.host=127.0.0.1
  3. spring.redis.port=6379
  4. spring.redis.password=tiger
  5.  
  6. #mybatis
  7. #开启mybatis驼峰命名，这样可以将mysql中带有下划线的映射成驼峰命名的字段
  8. mybatis.configuration.map-underscore-to-camel-case=true
  9.  
  10. #datasource
  11. spring.datasource.url=jdbc:mysql://127.0.0.1:3306/tiger?useUnicode=true&characterEncoding=UTF-8&zeroDateTimeBehavior=convertToNull&autoReconnect=true&generateSimpleParameterMetadata=true
  12. spring.datasource.username=tiger
  13. spring.datasource.password=tiger
  14. spring.datasource.driver-class-name=com.mysql.jdbc.Driver
  15. spring.datasource.type=com.alibaba.druid.pool.DruidDataSource
  16. spring.datasource.max-idle=10
  17. spring.datasource.max-wait=60000
  18. spring.datasource.min-idle=5
  19. spring.datasource.initial-size=5
  20. spring.datasource.validationQuery=select 'x'

三、说明

1、controller层使用注解@RestController，这样返回结果就是json格式，而@Controller返回结果是字符串

2、throw 异常

如果exception类型是自定义的异常StudentException，直接抛出，如果是其它异常统一抛出网络错误

  1. try{
  2.  
  3. }catch (Exception e){
  4.             if(e instanceof StudentException){
  5.                 throw e;
  6.             }else {
  7.                 log.error("findByStudentId error:",e);
  8.                 throw new StudentException(ErrorCodeAndMsg.Network_error);
  9.        }
  10. }

3、在返回结果类添加了注解@JsonSerialize(include= JsonSerialize.Inclusion.NON_NULL)

是因为更新或者删除操作，一般没有返回值，我只需要知道是否更新成功或者删除成功就OK了，如果不加这个注解

我们返回的结果中data为null！！！

  1. {
  2.     "data": null,
  3.     "code": "0000",
  4.     "msg": "请求成功"
  5. }

加上注解再更新数据，返回结果：

  1. {
  2.     "code": "0000",
  3.     "msg": "请求成功"
  4. }

因此这个注解的作用就是：返回结果中有null值，干掉它！

四、测试结果

mysql数据库中有一条学号为13240115的数据：

1、student_id = "13240115"时

  1. {
  2.     "data": {
  3.         "id": 1,
  4.         "studentId": "13240115",
  5.         "name": "Tiger",
  6.         "age": 25,
  7.         "famillyAddress": "北京",
  8.         "createdDate": "2018-10-08T05:45:49.000+0000",
  9.         "updatedDate": "2018-10-09T05:36:36.000+0000"
  10.     },
  11.     "code": "0000",
  12.     "msg": "请求成功"
  13. }

2、student_id = "13240114"时

  1. {
  2.     "code": "0001",
  3.     "msg": "学号不存在"
  4. }

3、student_id = "1324011"，不足8位时

  1. {
  2.     "code": "0002",
  3.     "msg": "学号长度不足"
  4. }

4、student_id = "13240115"，然后在接口中加上一行代码，System.out.println(1/0);

返回结果：

  1. {
  2.     "code": "9999",
  3.     "msg": "网络错误，待会重试"
  4. }

控制台日志：

  1. java.lang.ArithmeticException: / by zero
  2.  at com.dl.cn.message.controller.StudentInofController.findByStudentId(StudentInofController.java:54) ~[classes/:na]
  3.    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_161]
  4.  at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_161]
  5.  at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_161]
  6.  at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_161]
  7.   at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:209) [spring-web-5.0.8.RELEASE.jar:5.0.8.RELEASE]
  8.  at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:136) [spring-web-5.0.8.RELEASE.jar:5.0.8.RELEASE]

通过测试，发现这个小案例满足刚开始我们提出的需求，一定还有很多其它问题，暂时没有发现，我会及时修改，不知道有人是否看我的博客？我只是想把自己的学习成果总结记录下来。人可以成长为芳草，也可以长成杂莠！！！

原文地址：https://blog.csdn.net/qq_31289187/article/details/82980714

02-12 17:27
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