本文主要是介绍Java异常处理-前端参数优雅返回异常结果，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！
目录
目录
1 引言
2 什么是异常
2.1 Java中的异常体系
3 常见的处理方式
3.1 参数传递结果
3.2 每个方法都返回结果对象，或者状态码
错误码
调用的方法都返回错误码
3.3 自定义异常并捕获处理
异常定义
异常处理
4 spring-boot中处理方式
4.1 controller
4.2 数据传输对象
4.3 自定义校验注解
4.4 解释注解
4.5 全局处理异常
5 效果
5.1 自定义参数异常
5.2 自定义校验注解异常
1 引言
异常处理是程序员开发的必修课。
2 什么是异常
程序运行中的非正常行为，例如给用户的录入不符合规范，或者由于疏忽有的对象没有赋值，或者使用数组时调用的下标超标等等都可以称为程序的异常。异常都会造成程序出错中断，是很严重的行为，所以我们要处理可能出现的各种异常。
2.1 Java中的异常体系
待补充理论知识
3 常见的处理方式
处理异常的方式很多。
3.1 参数传递结果
以下代码模拟登录操作，传入的用户名和密码，先后经过用户名校验、密码校验、查询数据库，并返回结果。这里使用Response透传整个处理流程。
package com.param.validate.main;import com.alibaba.fastjson.JSON;
import com.param.validate.common.constant.UserConstant;
import com.param.validate.common.enums.ResponseCode;
import com.param.validate.dto.UserDTO;
import com.param.validate.vo.Response;
import com.param.validate.vo.UserVO;/*** Description of this file** @author qiu* @version 1.0* @since 2021/12/29*/
public class LoginMain {/*** 登录过程* @param userDTO 用户数据传输对象* @return*/public Response<UserVO> login(UserDTO userDTO){// 事先声明一个最终对象，该对象会伴随后续处理Response<UserVO> response = new Response<>();checkUsername(userDTO.getUsername(),response);if(response.getCode()!=null){return response;}checkPassword(userDTO.getUsername(),response);if(response.getCode()!=null){return response;}UserVO userVO = mockQueryUserInfo(userDTO.getUsername(), userDTO.getPassword());response.setCode(ResponseCode.OK.getCode());response.setMessage(ResponseCode.OK.getMessage());response.setResult(userVO);return response;}/*** 校验用户名* @param username 用户名* @param response 返回结果*/public void checkUsername(String username, Response<UserVO> response){// 不能为空if(null==username||username.length()==0){response.setCode(ResponseCode.USERNAME_EMPTY.getCode());response.setMessage(ResponseCode.USERNAME_EMPTY.getMessage());return;}// 长度不能超过32位if(username.length()> UserConstant.USERNAME_LIMIT){response.setCode(ResponseCode.USERNAME_INVALID.getCode());response.setMessage(ResponseCode.USERNAME_INVALID.getMessage());}}/*** 校验密码* @param password 密码* @param response 返回结果*/public void checkPassword(String password,Response<UserVO> response){// 不能为空if(null==password||password.length()==0){response.setCode(ResponseCode.PASSWORD_EMPTY.getCode());response.setMessage(ResponseCode.PASSWORD_EMPTY.getMessage());return;}// 长度不能超过16位if(password.length()> UserConstant.PASSWORD_LIMIT){response.setCode(ResponseCode.PASSWORD_INVALID.getCode());response.setMessage(ResponseCode.PASSWORD_INVALID.getMessage());}}/*** 模拟登录* @param username 用户名* @param password 密码* @return*/public UserVO mockQueryUserInfo(String username, String password) {return UserVO.builder().username(username).password(password).age(18).sex("男").build();}public static void main(String[] args) {UserDTO userDTO = new UserDTO("","123456");LoginMain loginMain = new LoginMain();Response<UserVO> login = loginMain.login(userDTO);System.out.println(JSON.toJSONString(login));}
}3.2 每个方法都返回结果对象，或者状态码
错误码
package com.param.validate.common.enums;import com.param.validate.vo.Response;
import lombok.Getter;
import org.springframework.http.HttpStatus;/*** Description of this file** @author qiu* @version 1.0* @since 2021/12/29*/
@Getter
public enum ResponseCode {/*** 0,代表成功*/OK(HttpStatus.OK, 0, "成功"),/*** [-100000~0),参数错误*/USERNAME_EMPTY(HttpStatus.BAD_REQUEST, -100001, "用户名为空"),USERNAME_INVALID(HttpStatus.BAD_REQUEST, -100002, "用户名无效"),PASSWORD_EMPTY(HttpStatus.BAD_REQUEST, -100003, "密码为空"),PASSWORD_INVALID(HttpStatus.BAD_REQUEST, -100004, "密码无效"),PARAM_ERROR(HttpStatus.BAD_REQUEST,-100005,"参数错误"),/*** [-200000,-100000)，服务端内部错误*/QUERY_USERNAME_ERROR(HttpStatus.INTERNAL_SERVER_ERROR, -200001, "查询用户名异常"),UNKOWN(HttpStatus.INTERNAL_SERVER_ERROR, -200002, "未知错误");private HttpStatus httpStatus;private Integer code;private String message;ResponseCode(HttpStatus httpStatus, Integer code, String message) {this.httpStatus = httpStatus;this.code = code;this.message = message;}
}
调用的方法都返回错误码
package com.param.validate.main;import com.alibaba.fastjson.JSON;
import com.param.validate.common.constant.UserConstant;
import com.param.validate.common.enums.ResponseCode;
import com.param.validate.dto.UserDTO;
import com.param.validate.vo.Response;
import com.param.validate.vo.UserVO;
import org.apache.catalina.User;/*** Description of this file** @author qiu* @version 1.0* @since 2021/12/29*/
public class LoginOtherMain {/*** 登录过程* @param userDTO 用户数据传输对象* @return*/public Response<UserVO> login(UserDTO userDTO){ResponseCode responseCode = checkUsername(userDTO.getUsername());if(responseCode!=null){return Response.error(responseCode);}ResponseCode code = checkPassword(userDTO.getUsername());if(code!=null){return Response.error(code);}Response<UserVO> response = new Response<UserVO>();UserVO userVO = mockQueryUserInfo(userDTO.getUsername(), userDTO.getPassword());response.setCode(ResponseCode.OK.getCode());response.setMessage(ResponseCode.OK.getMessage());response.setResult(userVO);return response;}/*** 校验用户名* @param username 用户名*/public ResponseCode checkUsername(String username){// 不能为空if(null==username||username.length()==0){return ResponseCode.USERNAME_EMPTY;}// 长度不能超过32位if(username.length()> UserConstant.USERNAME_LIMIT){return ResponseCode.USERNAME_INVALID;}return null;}/*** 校验密码* @param password 密码*/public ResponseCode checkPassword(String password){// 不能为空if(null==password||password.length()==0){return ResponseCode.PASSWORD_EMPTY;}// 长度不能超过16位if(password.length()> UserConstant.PASSWORD_LIMIT){return ResponseCode.PASSWORD_INVALID;}return null;}/*** 模拟登录* @param username 用户名* @param password 密码* @return*/public UserVO mockQueryUserInfo(String username, String password) {return UserVO.builder().username(username).password(password).age(18).sex("男").build();}public static void main(String[] args) {UserDTO userDTO = new UserDTO("","123456");LoginOtherMain loginOtherMain = new LoginOtherMain();Response<UserVO> login = loginOtherMain.login(userDTO);System.out.println(JSON.toJSONString(login));}}
3.3 自定义异常并捕获处理
自定义异常并捕获处理。
异常定义
package com.param.validate.common.exception;import com.param.validate.common.enums.ResponseCode;
import lombok.Getter;
import lombok.Setter;/*** Description of this file** @author qiu* @version 1.0* @since 2021/12/29*/
@Setter
@Getter
public class LoginExcetion extends RuntimeException{private ResponseCode code;public LoginExcetion (ResponseCode code) {super(code.getMessage());this.code = code;}/*** 不写入堆栈信息，提高性能*/@Overridepublic Throwable fillInStackTrace() {return this;}}
异常处理
package com.param.validate.main;import com.alibaba.fastjson.JSON;
import com.param.validate.common.constant.UserConstant;
import com.param.validate.common.enums.ResponseCode;
import com.param.validate.common.exception.LoginExcetion;
import com.param.validate.dto.UserDTO;
import com.param.validate.vo.Response;
import com.param.validate.vo.UserVO;
import org.apache.catalina.User;
import org.apache.logging.log4j.LoggingException;/*** Description of this file** @author qiu* @version 1.0* @since 2021/12/29*/
public class LoginOtherMain {/*** 登录过程** @param userDTO 用户数据传输对象* @return*/public Response<UserVO> login(UserDTO userDTO) {checkUsername(userDTO.getUsername());checkPassword(userDTO.getUsername());UserVO userVO = mockQueryUserInfo(userDTO.getUsername(), userDTO.getPassword());Response<UserVO> response = new Response<UserVO>();response.setCode(ResponseCode.OK.getCode());response.setMessage(ResponseCode.OK.getMessage());response.setResult(userVO);return response;}/*** 校验用户名** @param username 用户名*/public void checkUsername(String username) {// 不能为空if (null == username || username.length() == 0) {throw new LoginExcetion(ResponseCode.USERNAME_EMPTY);}// 长度不能超过32位if (username.length() > UserConstant.USERNAME_LIMIT) {throw new LoginExcetion(ResponseCode.USERNAME_INVALID);}}/*** 校验密码** @param password 密码*/public void checkPassword(String password) {// 不能为空if (null == password || password.length() == 0) {throw new LoginExcetion(ResponseCode.PASSWORD_EMPTY);}// 长度不能超过16位if (password.length() > UserConstant.PASSWORD_LIMIT) {throw new LoginExcetion(ResponseCode.PASSWORD_INVALID);}}/*** 模拟登录** @param username 用户名* @param password 密码* @return*/public UserVO mockQueryUserInfo(String username, String password) {return UserVO.builder().username(username).password(password).age(18).sex("男").build();}public static void main(String[] args) {UserDTO userDTO = new UserDTO("", "123456");LoginOtherMain loginOtherMain = new LoginOtherMain();Response<UserVO> login = null;try {login = loginOtherMain.login(userDTO);} catch (LoginExcetion e) {login = Response.error(e.getCode());} catch (Exception e) {login =Response.error(ResponseCode.UNKOWN);}System.out.println(JSON.toJSONString(login));}}
4 spring-boot中处理方式
4.1 controller
controller会校验post参数和get参数。
package com.param.validate.controller;import javax.validation.Valid;
import javax.validation.constraints.Size;import com.param.validate.dto.UserDTO;
import com.param.validate.service.LoginService;
import com.param.validate.validator.annotation.ValidPassword;
import com.param.validate.vo.Response;
import com.param.validate.vo.UserVO;
import lombok.Getter;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.ResponseEntity;
import org.springframework.validation.annotation.Validated;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;/*** Description of this file** @author qiu* @version 1.0* @since 2021/12/29*/@Slf4j
@RequestMapping("/v1/user/login")
@RestController
// get校验时需要这个
@Validated
public class LoginController {@Autowiredprivate LoginService loginService;@PostMappingpublic ResponseEntity<Response<UserVO>> login(@Valid @RequestBody UserDTO userDTO){UserVO user = loginService.findUser(userDTO.getUsername(), userDTO.getPassword());return ResponseEntity.ok(Response.ok(user));}@GetMapping("/{password}")public ResponseEntity<Response<UserVO>> getUserVO(@PathVariable("password")@Size(min = 8,max = 32,message = "密码区间限制")String password){UserVO userVO = UserVO.builder().username("zhangsansssssss").password(password).build();return ResponseEntity.ok(Response.ok(userVO));}}
4.2 数据传输对象
传入的登录对象,使用自定义注解校验参数
package com.param.validate.dto;import javax.validation.constraints.NotEmpty;
import javax.validation.constraints.Size;import com.param.validate.validator.annotation.ValidPassword;
import lombok.Getter;
import lombok.Setter;/*** Description of this file** @author qiu* @version 1.0* @since 2021/12/29*/
@Setter
@Getter
public class UserDTO {@NotEmpty(message = "Username is empty.")@Size(min = 8,max = 32,message = "Username length invalid.")private String username;@NotEmpty(message = "Password is empty.")@Size(min = 8,max = 32,message = "Password length invalid.")@ValidPasswordprivate String password;public UserDTO(String username, String password) {this.username = username;this.password = password;}public UserDTO(){}
}
4.3 自定义校验注解
/** Copyright (c) 2021, TP-Link Corporation Limited. All rights reserved.*/package com.param.validate.validator.annotation;import java.lang.annotation.Documented;
import java.lang.annotation.Retention;
import java.lang.annotation.Target;
import javax.validation.Constraint;
import javax.validation.Payload;import com.param.validate.validator.PasswordValidator;import static java.lang.annotation.ElementType.ANNOTATION_TYPE;
import static java.lang.annotation.ElementType.CONSTRUCTOR;
import static java.lang.annotation.ElementType.FIELD;
import static java.lang.annotation.ElementType.METHOD;
import static java.lang.annotation.ElementType.PARAMETER;
import static java.lang.annotation.RetentionPolicy.RUNTIME;/*** Description** @author qiu* @version 1.0*/
@Target({METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER})
@Retention(RUNTIME)
@Documented
@Constraint(validatedBy = PasswordValidator.class)
public @interface ValidPassword {String message() default "密码只能是数字";Class<?>[] groups() default {};Class<? extends Payload>[] payload() default {};}
4.4 解释注解
/** Copyright (c) 2021, TP-Link Corporation Limited. All rights reserved.*/
package com.param.validate.validator;import java.util.regex.Matcher;
import java.util.regex.Pattern;
import javax.validation.ConstraintValidator;
import javax.validation.ConstraintValidatorContext;import com.param.validate.validator.annotation.ValidPassword;
import lombok.extern.slf4j.Slf4j;/*** Description** @author qiu* @version 1.0*/
@Slf4j
public class PasswordValidator implements ConstraintValidator<ValidPassword, String> {@Overridepublic void initialize(ValidPassword constraintAnnotation) {}@Overridepublic boolean isValid(String value, ConstraintValidatorContext context) {if (value == null) {return true;}boolean matches = value.matches("[0-9]+");if(matches){return true;}return false;}
}
4.5 全局处理异常
package com.param.validate.handler;import java.util.List;
import java.util.Set;
import javax.servlet.http.HttpServletRequest;
import javax.validation.ConstraintViolation;
import javax.validation.ConstraintViolationException;import com.param.validate.common.enums.ResponseCode;
import com.param.validate.common.exception.LoginExcetion;
import com.param.validate.common.exception.QueryException;
import com.param.validate.vo.Response;
import lombok.extern.slf4j.Slf4j;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.validation.ObjectError;
import org.springframework.web.bind.MethodArgumentNotValidException;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.bind.annotation.RestControllerAdvice;/*** Description of this file** @author qiu* @version 1.0* @since 2021/12/30*/
@Slf4j
@RestControllerAdvice
public class GlobalExceptionHandler {/*** 处理get方法的参数异常情况* @param request 请求体，如果需要获取请求体的信息时，可以用到* @param ex 抛出的异常* @return*/@ExceptionHandler(ConstraintViolationException.class)@ResponseBodypublic ResponseEntity handlerConstraintViolationException(HttpServletRequest request,ConstraintViolationException ex) {Set<ConstraintViolation<?>> errors = ex.getConstraintViolations();StringBuilder messageBuilder = new StringBuilder();errors.forEach(constraintViolation -> messageBuilder.append(constraintViolation.getMessage()));return ResponseEntity.status(HttpStatus.BAD_REQUEST).body(Response.error(ResponseCode.PARAM_ERROR.getCode(), messageBuilder.toString()));}/*** 使用@RequestBody @Valid 对JSON参数进行获取和校验，抛出异常会走该路径* @param request 请求体，如果要用到的话* @param ex 抛出的异常* @return*/@ExceptionHandler(value = MethodArgumentNotValidException.class)@ResponseBodypublic ResponseEntity handlerBeanValidationException(HttpServletRequest request,MethodArgumentNotValidException ex) {System.out.println("222");List<ObjectError> errors = ex.getBindingResult().getAllErrors();StringBuilder messageBuilder = new StringBuilder();errors.forEach(error -> messageBuilder.append(error.getDefaultMessage()).append(";"));return ResponseEntity.status(HttpStatus.BAD_REQUEST).body(Response.error(ResponseCode.PARAM_ERROR.getCode(), messageBuilder.toString()));}/**** @param e 抛出的自定义异常* @return*/@ExceptionHandler(LoginExcetion.class)public ResponseEntity handleLoginExcetion(LoginExcetion e) {ResponseCode code = e.getCode();return ResponseEntity.status(code.getHttpStatus()).body(Response.error(code));}/**** @param e 抛出的自定义异常* @return*/@ExceptionHandler(QueryException.class)public ResponseEntity handleCombinedException(QueryException e) {ResponseCode code = e.getCode();return ResponseEntity.status(code.getHttpStatus()).body(Response.error(code));}/**** @param e 程序没有处理的未知异常* @return*/@ExceptionHandler(Exception.class)public ResponseEntity handleException(Exception e) {return ResponseEntity.status(HttpStatus.INTERNAL_SERVER_ERROR).body(Response.error(ResponseCode.UNKOWN));}
}
5 效果
5.1 自定义参数异常
5.2 自定义校验注解异常
5.3 get方法校验
这篇关于Java异常处理-前端参数优雅返回异常结果的文章就介绍到这儿，希望我们推荐的文章对编程师们有所帮助！
