spring-boot - 为 Spring Boot 代码添加自定义异常的最佳方法
问题描述
发生异常时如何显示相应的错误消息。
假设在 GET 方法期间如果找不到数据,它应该显示自定义异常消息。
同样,如果我们试图删除不可用的数据。
汽车.java
package com.car_rental_project.car_project;
import javax.persistence.Entity;
import javax.persistence.Id;
@Entity
public class Car {
@Id
private String id;
private String modelname;
private String type;
private String year_of_registration;
private String seating_capacity;
private String cost_per_day;
private String milleage;
private String pincode;
private String contact_number;
private String email;
public Car() {
}
public Car(String id, String modelname, String type, String year_of_registration, String seating_capacity,String cost_per_day, String milleage, String pincode, String contact_number, String email) {
super();
this.id = id;
this.modelname = modelname;
this.type = type;
this.year_of_registration = year_of_registration;
this.seating_capacity = seating_capacity;
this.cost_per_day = cost_per_day;
this.milleage = milleage;
this.pincode = pincode;
this.contact_number = contact_number;
this.email = email;
}
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getModelname() {
return modelname;
}
public void setModelname(String modelname) {
this.modelname = modelname;
}
public String getType() {
return type;
}
public void setType(String type) {
this.type = type;
}
public String getYear_of_registration() {
return year_of_registration;
}
public void setYear_of_registration(String year_of_registration) {
this.year_of_registration = year_of_registration;
}
public String getSeating_capacity() {
return seating_capacity;
}
public void setSeating_capacity(String seating_capacity) {
this.seating_capacity = seating_capacity;
}
public String getCost_per_day() {
return cost_per_day;
}
public void setCost_per_day(String cost_per_day) {
this.cost_per_day = cost_per_day;
}
public String getMilleage() {
return milleage;
}
public void setMilleage(String milleage) {
this.milleage = milleage;
}
public String getPincode() {
return pincode;
}
public void setPincode(String pincode) {
this.pincode = pincode;
}
public String getContact_number() {
return contact_number;
}
public void setContact_number(String contact_number) {
this.contact_number = contact_number;
}
public String getEmail() {
return email;
}
public void setEmail(String email) {
this.email = email;
}
}
汽车服务.java
package com.car_rental_project.car_project;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
@Service
public class CarService {
@Autowired
private CarRepository CarRepository;
public List<Car> getAllCars() {
return (List<Car>) CarRepository.findAll();
}
public Car getCar(String id) {
return (Car) CarRepository.findOne(id);
}
public void addCar(Car car) {
this.CarRepository.save(car);
}
public void updateCar(String id, Car car) {
this.CarRepository.save(car);
}
public void deleteCar(String id) {
this.CarRepository.delete(id);;
}
}
汽车控制器.java
package com.car_rental_project.car_project;
import java.util.List;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.DeleteMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.PutMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;
@RestController
public class CarController {
@Autowired
private CarService carService;
@RequestMapping("/car")
public List<Car> getAllCars() {
return carService.getAllCars();
}
@RequestMapping("/car/{id}")
public Car getCar(@PathVariable String id) {
return carService.getCar(id);
}
//@PostMapping("/car")
@RequestMapping(method=RequestMethod.POST, value="/car")
public String addCar(@RequestBody Car car) {
carService.addCar(car);
String response = "{\"success\": true, \"message\": Car has been added successfully.}";
return response;
}
//@RequestMapping(method=RequestMethod.PUT, value="/car/{id}")
@PutMapping("/car/{id}")
public String updateCar(@RequestBody Car car, @PathVariable String id) {
carService.updateCar(id, car);
String response = "{\"success\": true, \"message\": Car has been updated successfully.}";
return response;
}
//@RequestMapping(method=RequestMethod.DELETE, value="/topics/{id}")
@DeleteMapping("/car/{id}")
public String deleteCar(@PathVariable String id) {
carService.deleteCar(id);
String response = "{\"success\": true, \"message\": Car has been deleted successfully.}";
return response;
}
}
解决方案
以下是您可以遵循的一些方法来处理您的自定义异常。
创建一个 POJO 来处理您的自定义错误消息并放置您想要返回的属性。
public class ErrorResponse {
private String message;
public String getMessage() {
return message;
}
public void setMessage(String message) {
this.message = message;
}
}
方法 1. 在您的 Controller 方法中。
@RequestMapping("/car/{id}")
public ResponseEntity<?> getCar(@PathVariable String id) {
Car car = carService.getCar(id);
if (car == null) {
ErrorResponse errorResponse = new ErrorResponse();
errorResponse.setMessage("Record not found");
return new ResponseEntity<>(errorResponse, HttpStatus.NOT_FOUND)
}
return new ResponseEntity<>(car, HttpStatus.OK);
}
方法 2:全局处理异常。
步骤 1:创建 NotFound 异常类并扩展为 RunTime Exception。
public class NoRecordFoundException extends RuntimeException {
public NoRecordFoundException() {
super();
}
}
第 2 步:创建全局异常处理程序
@RestControllerAdvice
public class GlobalExceptionHandler {
@ExceptionHandler(NoRecordFoundException.class)
@ResponseStatus(HttpStatus.NOT_FOUND)
@ResponseBody
public ErrorResponse handleNoRecordFoundException(NoRecordFoundException ex)
{
ErrorResponse errorResponse = new ErrorResponse();
errorResponse.setMessage("No Record Found");
return errorResponse;
}
//同样你可以处理内部异常错误
@ExceptionHandler(Exception.class)
@ResponseStatus(HttpStatus.INTERNAL_SERVER_ERROR)
@ResponseBody
public ErrorResponse handleDefaultException(Exception ex) {
ErrorResponse response = new ErrorResponse();
response.setMessage(ex.getMessage());
return response;
}
}
第 3 步:从您的控制器或服务中抛出 Not found 异常:
@RequestMapping("/car/{id}")
public ResponseEntity<?> getCar(@PathVariable String id) {
Car car = carService.getCar(id);
if (car == null) {
throw new NoRecordFoundException();
}
return new ResponseEntity<>(car, HttpStatus.OK);
}
方法3:@ExceptionHandler
在控制器内创建并抛出
@ExceptionHandler(NoRecordFoundException.class)
@ResponseStatus(HttpStatus.NOT_FOUND)
@ResponseBody
public ErrorResponse handleNoRecordFoundException(NoRecordFoundException ex) {
ErrorResponse errorResponse = new ErrorResponse();
errorResponse.setMessage("No Record Found");
return errorResponse;
}
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