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。
{
"data": {
"id": 1,
"studentId": "13240115",
"name": "Tiger",
"age": 25,
"famillyAddress": "北京",
"createdDate": "2018-10-08T05:45:49.000+0000",
"updatedDate": "2018-10-09T03:15:33.000+0000"
},
"code": "0000",
"msg": "请求成功"
}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。
{
"code": "0001",
"msg": "学号不存在"
}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
CREATE TABLE student_info (
id bigint(20) NOT NULL AUTO_INCREMENT COMMENT '自增',
student_id varchar(20) NOT NULL COMMENT '学号',
name varchar(64) NOT NULL COMMENT '姓名',
age int(2) NOT NULL COMMENT '年龄',
familly_address varchar(256) NOT NULL COMMENT '家庭地址',
created_date datetime NOT NULL DEFAULT CURRENT_TIMESTAMP COMMENT '创建时间',
updated_date datetime NOT NULL DEFAULT CURRENT_TIMESTAMP COMMENT '更新时间',
PRIMARY KEY (student_id),
KEY id (id)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb42、pom.xml
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-redis</artifactId>
</dependency>
<dependency>
<groupId>org.mybatis.spring.boot</groupId>
<artifactId>mybatis-spring-boot-starter</artifactId>
<version>1.3.1</version>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.46</version>
</dependency>
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>druid</artifactId>
<version>1.1.9</version>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<version>1.16.22</version>
</dependency>
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>fastjson</artifactId>
<version>1.2.43</version>
</dependency>
<dependency>
<groupId>com.squareup.okhttp3</groupId>
<artifactId>okhttp</artifactId>
<version>3.9.1</version>
</dependency>
<dependency>
<groupId>org.glassfish</groupId>
<artifactId>javax.json</artifactId>
<version>1.0.4</version>
</dependency>
<dependency>
<groupId>org.apache.tomcat.embed</groupId>
<artifactId>tomcat-embed-jasper</artifactId>
</dependency>
</dependencies>3、案例中使用redis进行缓存，可以不需要
4、创建实体类：StudentInfo
package com.dl.cn.message.bean;
import lombok.AllArgsConstructor;
import lombok.Builder;
import lombok.Data;
import lombok.NoArgsConstructor;
import java.io.Serializable;
import java.util.Date;
/**
* Created by Tiger on 2018/10/8.
*/
@Data
@Builder
@AllArgsConstructor
@NoArgsConstructor
public class StudentInfo implements Serializable{
private static final long serialVersionUID = 2597547944454691103L;
private Long id;
private String studentId;
private String name;
private Integer age;
private String famillyAddress;
private Date createdDate;
private Date updatedDate;
}
5、创建Mapper：StudentInfoMapper
package com.dl.cn.message.mapper;
import com.dl.cn.message.bean.StudentInfo;
import org.apache.ibatis.annotations.*;
/**
* Created by Tiger on 2018/10/8.
*/
@Mapper
public interface StudentInfoMapper {
@Insert("insert into student_info(student_id,name,age,familly_address)" +
" values(#{studentId},#{name},#{age},#{famillyAddress})")
/**
* 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
* */
void saveStudentInfo(StudentInfo studentInfo);
@Select("select * from student_info where student_id = #{studentId}")
StudentInfo findByStudentId(@Param("studentId") String studentId);
@Update("update student_info set familly_address = #{famillyAddress},updated_date = now() ")
void updateFamillyAddress(@Param("studentId") String studentId,@Param("famillyAddress") String famillyAddress);
}
6、创建service：StudentInfoService
package com.dl.cn.message.service;
import com.dl.cn.message.bean.StudentInfo;
import com.dl.cn.message.mapper.StudentInfoMapper;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cache.annotation.CacheConfig;
import org.springframework.cache.annotation.CacheEvict;
import org.springframework.cache.annotation.Cacheable;
import org.springframework.stereotype.Service;
/**
* Created by Tiger on 2018/10/8.
*/
@Service
@CacheConfig(cacheNames = "studentInfo")
@Slf4j
public class StudentInfoService {
@Autowired
StudentInfoMapper studentInfoMapper;
/**
* 保存学生信息
* @param studentInfo
* */
public void saveStudentInfo(StudentInfo studentInfo){
studentInfoMapper.saveStudentInfo(studentInfo);
}
/**
* 根据学号查学生信息
* @param studentId
* @return
* */
@Cacheable(key = "#studentId",unless = "#result == null")
public StudentInfo findByStudentId(String studentId){
log.info("查找信息:{}",studentId);
return studentInfoMapper.findByStudentId(studentId);
}
/**
* 根据学号更新家庭地址
* @param studentId
* @param famillyAddress
* */
//删除对应key的缓存
@CacheEvict(key = "#studentId")
public void updateFamillyAddress(String studentId,String famillyAddress){
studentInfoMapper.updateFamillyAddress(studentId,famillyAddress);
}
}
7、创建统一返回结果类：Response
package com.dl.cn.message.response;
import com.fasterxml.jackson.databind.annotation.JsonSerialize;
import lombok.Getter;
import lombok.Setter;
import java.io.Serializable;
/**
* 请求返回类
* Created by Tiger on 2018/10/9.
*/
@Getter
@Setter
@JsonSerialize(include= JsonSerialize.Inclusion.NON_NULL)
public class Response<T> implements Serializable {
private static final long serialVersionUID = -4505655308965878999L;
//请求成功返回码为：0000
private static final String successCode = "0000";
//返回数据
private T data;
//返回码
private String code;
//返回描述
private String msg;
public Response(){
this.code = successCode;
this.msg = "请求成功";
}
public Response(String code,String msg){
this();
this.code = code;
this.msg = msg;
}
public Response(String code,String msg,T data){
this();
this.code = code;
this.msg = msg;
this.data = data;
}
public Response(T data){
this();
this.data = data;
}
}
8、创建异常编码和描述类：ErrorCodeAndMsg
package com.dl.cn.message.enums;
/**
* Created by Tiger on 2018/10/9.
*/
public enum ErrorCodeAndMsg {
Student_number_does_not_exist("0001","学号不存在"),
Insufficient_student_number("0002","学号长度不足"),
Student_number_is_empty("0003","学号为空"),
Network_error("9999","网络错误，待会重试"),
;
private String code;
private String msg;
ErrorCodeAndMsg(String code, String msg) {
this.code = code;
this.msg = msg;
}
public String getCode() {
return code;
}
public void setCode(String code) {
this.code = code;
}
public String getMsg() {
return msg;
}
public void setMsg(String msg) {
this.msg = msg;
}
}
9、创建统一异常处理类：StudentException
package com.dl.cn.message.exception;
import com.dl.cn.message.enums.ErrorCodeAndMsg;
import java.io.Serializable;
/**
* 统一异常捕获类
* Created by Tiger on 2018/10/9.
*/
public class StudentException extends RuntimeException{
private static final long serialVersionUID = -6370612186038915645L;
private final ErrorCodeAndMsg response;
public StudentException(ErrorCodeAndMsg response) {
this.response = response;
}
public ErrorCodeAndMsg getResponse() {
return response;
}
}
10、创建异常处理的全局配置类：ExceptionHandler
package com.dl.cn.message.exception;
import com.dl.cn.message.enums.ErrorCodeAndMsg;
import com.dl.cn.message.response.Response;
import lombok.extern.slf4j.Slf4j;
import org.springframework.web.bind.annotation.ControllerAdvice;
import org.springframework.web.bind.annotation.ResponseBody;
import javax.servlet.http.HttpServletRequest;
/**
* Created by Tiger on 2018/10/9.
*/
@ControllerAdvice
@Slf4j
public class ExceptionHandler {
@org.springframework.web.bind.annotation.ExceptionHandler(StudentException.class)
@ResponseBody
public Response handleStudentException(HttpServletRequest request, StudentException ex) {
Response response;
log.error("StudentException code:{},msg:{}",ex.getResponse().getCode(),ex.getResponse().getMsg());
response = new Response(ex.getResponse().getCode(),ex.getResponse().getMsg());
return response;
}
@org.springframework.web.bind.annotation.ExceptionHandler(Exception.class)
@ResponseBody
public Response handleException(HttpServletRequest request, Exception ex) {
Response response;
log.error("exception error:{}",ex);
response = new Response(ErrorCodeAndMsg.Network_error.getCode(),
ErrorCodeAndMsg.Network_error.getMsg());
return response;
}
}
11、创建controler类：StudentInofController
package com.dl.cn.message.controller;
import com.dl.cn.message.enums.ErrorCodeAndMsg;
import com.dl.cn.message.exception.StudentException;
import com.dl.cn.message.response.Response;
import com.dl.cn.message.service.StudentInfoService;
import com.dl.cn.message.bean.StudentInfo;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;
/**
* Created by Tiger on 2018/10/8.
*/
@RestController
@RequestMapping("/student")
@Slf4j
public class StudentInofController {
@Autowired
StudentInfoService studentInfoService;
/**
* 保存学生信息
* @param studentId
* @param name
* @param age
* @param famillyAddress
* */
@PostMapping("/save")
public void saveStudentInfo(@RequestParam("student_id") String studentId,
@RequestParam("name") String name,
@RequestParam("age") Integer age,
@RequestParam("familly_address") String famillyAddress){
StudentInfo studentInfo = StudentInfo.builder()
.studentId(studentId)
.name(name)
.age(age)
.famillyAddress(famillyAddress)
.build();
studentInfoService.saveStudentInfo(studentInfo);
}
/**
* 根据学号查学生信息
* @param studentId
* @return
* */
@PostMapping("/findByStudentId")
public Response findByStudentId(@RequestParam("student_id") String studentId){
try{
log.info("Get student information based on student number:{}",studentId);
if(studentId == null){
throw new StudentException(ErrorCodeAndMsg.Student_number_is_empty);
}
//学号固定为8位
if(studentId.length() != 8){
throw new StudentException(ErrorCodeAndMsg.Insufficient_student_number);
}
StudentInfo studentInfo = studentInfoService.findByStudentId(studentId);
if(studentInfo == null){
throw new StudentException(ErrorCodeAndMsg.Student_number_does_not_exist);
}
return new Response(studentInfo);
}catch (Exception e){
if(e instanceof StudentException){
throw e;
}else {
log.error("findByStudentId error:",e);
throw new StudentException(ErrorCodeAndMsg.Network_error);
}
}
}
@PostMapping("/updateFamillyAddress")
public Response updateFamillyAddress(@RequestParam("student_id") String studentId,
@RequestParam("familly_address") String famillyAddress){
studentInfoService.updateFamillyAddress(studentId,famillyAddress);
Response response = new Response();
System.out.println(response.toString());
return response;
}
}
12、application.properties配置
#redis
spring.redis.host=127.0.0.1
spring.redis.port=6379
spring.redis.password=tiger
#mybatis
#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
mybatis.configuration.map-underscore-to-camel-case=true
#datasource
spring.datasource.url=jdbc:mysql://127.0.0.1:3306/tiger?useUnicode=true&characterEncoding=UTF-8&zeroDateTimeBehavior=convertToNull&autoReconnect=true&generateSimpleParameterMetadata=true
spring.datasource.username=tiger
spring.datasource.password=tiger
spring.datasource.driver-class-name=com.mysql.jdbc.Driver
spring.datasource.type=com.alibaba.druid.pool.DruidDataSource
spring.datasource.max-idle=10
spring.datasource.max-wait=60000
spring.datasource.min-idle=5
spring.datasource.initial-size=5
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
try{
}catch (Exception e){
if(e instanceof StudentException){
throw e;
}else {
log.error("findByStudentId error:",e);
throw new StudentException(ErrorCodeAndMsg.Network_error);
}
}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！！！
{
"data": null,
"code": "0000",
"msg": "请求成功"
}加上注解再更新数据，返回结果：
{
"code": "0000",
"msg": "请求成功"
}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
{
"data": {
"id": 1,
"studentId": "13240115",
"name": "Tiger",
"age": 25,
"famillyAddress": "北京",
"createdDate": "2018-10-08T05:45:49.000+0000",
"updatedDate": "2018-10-09T05:36:36.000+0000"
},
"code": "0000",
"msg": "请求成功"
}2、student_id = "13240114"时
{
"code": "0001",
"msg": "学号不存在"
}3、student_id = "1324011"，不足8位时
{
"code": "0002",
"msg": "学号长度不足"
}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：
{
"code": "9999",
"msg": "网络错误，待会重试"
}控制台日志：
java.lang.ArithmeticException: / by zero
at com.dl.cn.message.controller.StudentInofController.findByStudentId(StudentInofController.java:54) ~[classes/:na]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_161]
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_161]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_161]
at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_161]
at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:209) [spring-web-5.0.8.RELEASE.jar:5.0.8.RELEASE]
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！！！