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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
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  • 原文地址：https://www.cnblogs.com/jpfss/p/11591806.html
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