在本文中，我们将向您展示Spring Boot REST应用程序中的错误处理。
使用的技术：
- Spring Boot 2.1.2发布
- Spring 5.1.4。发布
- Maven 3
- Java 8
1. /error
1.1默认情况下，Spring Boot提供了一个BasicErrorController用于/error处理所有错误的映射控制器，并getErrorAttributes生成一个带有错误详细信息，HTTP状态和异常消息的JSON响应。
{
"timestamp":"2019-02-27T04:03:52.398+0000",
"status":500,
"error":"Internal Server Error",
"message":"...",
"path":"/path"
}
BasicErrorController.java
package org.springframework.boot.autoconfigure.web.servlet.error;
//...
@Controller
@RequestMapping("${server.error.path:${error.path:/error}}")
public class BasicErrorController extends AbstractErrorController {
//...
@RequestMapping
public ResponseEntity<Map<String, Object>> error(HttpServletRequest request) {
Map<String, Object> body = getErrorAttributes(request,
isIncludeStackTrace(request, MediaType.ALL));
HttpStatus status = getStatus(request);
return new ResponseEntity<>(body, status);
}
在IDE中，在此方法中放置一个断点，您将了解Spring Boot如何生成默认的JSON错误响应。
2.Custom Exception
在Spring Boot中，我们可以@ControllerAdvice用来处理自定义异常。
2.1Custom Exception
BookNotFoundException.java
package com.zthinker.error;
public class BookNotFoundException extends RuntimeException {
public BookNotFoundException(Long id) {
super("Book id not found : " + id);
}
}
如果未找到图书，则控制器抛出上述错误 BookNotFoundException
BookController.java
package com.zthinker;
//...
@RestController
public class BookController {
@Autowired
private BookRepository repository;
// Find
@GetMapping("/books/{id}")
Book findOne(@PathVariable Long id) {
return repository.findById(id)
.orElseThrow(() -> new BookNotFoundException(id));
}
//...
}
默认情况下，Spring Boot会生成以下JSON错误响应，即http 500错误。
curl localhost:8080/books/5
{
"timestamp":"2019-02-27T04:03:52.398+0000",
"status":500,
"error":"Internal Server Error",
"message":"Book id not found : 5",
"path":"/books/5"
}
2.2如果未找到图书，则应返回404错误而不是500错误，我们可以像这样重写状态代码：
CustomGlobalExceptionHandler.java
package com.zthinker.error;
import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.MethodArgumentNotValidException;
import org.springframework.web.bind.annotation.ControllerAdvice;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.RestControllerAdvice;
import org.springframework.web.context.request.WebRequest;
import org.springframework.web.servlet.mvc.method.annotation.ResponseEntityExceptionHandler;
import javax.servlet.http.HttpServletResponse;
import javax.validation.ConstraintViolationException;
import java.io.IOException;
import java.util.Date;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.stream.Collectors;
@ControllerAdvice
public class CustomGlobalExceptionHandler extends ResponseEntityExceptionHandler {
// Let Spring BasicErrorController handle the exception, we just override the status code
@ExceptionHandler(BookNotFoundException.class)
public void springHandleNotFound(HttpServletResponse response) throws IOException {
response.sendError(HttpStatus.NOT_FOUND.value());
}
//...
}
2.3现在返回404。
curl localhost:8080/books/5
{
"timestamp":"2019-02-27T04:21:17.740+0000",
"status":404,
"error":"Not Found",
"message":"Book id not found : 5",
"path":"/books/5"
}
2.4此外，我们可以自定义整个JSON错误响应：
CustomErrorResponse.java
package com.zthinker.error;
import com.fasterxml.jackson.annotation.JsonFormat;
import java.time.LocalDateTime;
public class CustomErrorResponse {
@JsonFormat(shape = JsonFormat.Shape.STRING, pattern = "yyyy-MM-dd hh:mm:ss")
private LocalDateTime timestamp;
private int status;
private String error;
//...getters setters
}
CustomGlobalExceptionHandler.java
package com.zthinker.error;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.ControllerAdvice;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.context.request.WebRequest;
import org.springframework.web.servlet.mvc.method.annotation.ResponseEntityExceptionHandler;
import java.time.LocalDateTime;
@ControllerAdvice
public class CustomGlobalExceptionHandler extends ResponseEntityExceptionHandler {
@ExceptionHandler(BookNotFoundException.class)
public ResponseEntity<CustomErrorResponse> customHandleNotFound(Exception ex, WebRequest request) {
CustomErrorResponse errors = new CustomErrorResponse();
errors.setTimestamp(LocalDateTime.now());
errors.setError(ex.getMessage());
errors.setStatus(HttpStatus.NOT_FOUND.value());
return new ResponseEntity<>(errors, HttpStatus.NOT_FOUND);
}
//...
}
curl localhost:8080/books/5
{
"timestamp":"2019-02-27 12:40:45",
"status":404,
"error":"Book id not found : 5"
}
3. JSR 303 Validation error
3.1对于Spring @valid验证错误，它将抛出handleMethodArgumentNotValid
CustomGlobalExceptionHandler.java
package com.zthinker.error;
import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.MethodArgumentNotValidException;
import org.springframework.web.bind.annotation.ControllerAdvice;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.context.request.WebRequest;
import org.springframework.web.servlet.mvc.method.annotation.ResponseEntityExceptionHandler;
import javax.servlet.http.HttpServletResponse;
import javax.validation.ConstraintViolationException;
import java.io.IOException;
import java.util.Date;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.stream.Collectors;
@ControllerAdvice
public class CustomGlobalExceptionHandler extends ResponseEntityExceptionHandler {
//...
// @Validate For Validating Path Variables and Request Parameters
@ExceptionHandler(ConstraintViolationException.class)
public void constraintViolationException(HttpServletResponse response) throws IOException {
response.sendError(HttpStatus.BAD_REQUEST.value());
}
// error handle for @Valid
@Override
protected ResponseEntity<Object>
handleMethodArgumentNotValid(MethodArgumentNotValidException ex,
HttpHeaders headers,
HttpStatus status, WebRequest request) {
Map<String, Object> body = new LinkedHashMap<>();
body.put("timestamp", new Date());
body.put("status", status.value());
//Get all fields errors
List<String> errors = ex.getBindingResult()
.getFieldErrors()
.stream()
.map(x -> x.getDefaultMessage())
.collect(Collectors.toList());
body.put("errors", errors);
return new ResponseEntity<>(body, headers, status);
}
}
4. ResponseEntityExceptionHandler
4.1如果不确定，Spring Boot会抛出什么异常，则在此方法中放置一个断点以进行调试。
ResponseEntityExceptionHandler.java
package org.springframework.web.servlet.mvc.method.annotation;
//...
public abstract class ResponseEntityExceptionHandler {
@ExceptionHandler({
HttpRequestMethodNotSupportedException.class,
HttpMediaTypeNotSupportedException.class,
HttpMediaTypeNotAcceptableException.class,
MissingPathVariableException.class,
MissingServletRequestParameterException.class,
ServletRequestBindingException.class,
ConversionNotSupportedException.class,
TypeMismatchException.class,
HttpMessageNotReadableException.class,
HttpMessageNotWritableException.class,
MethodArgumentNotValidException.class,
MissingServletRequestPartException.class,
BindException.class,
NoHandlerFoundException.class,
AsyncRequestTimeoutException.class
})
@Nullable
public final ResponseEntity<Object> handleException(Exception ex, WebRequest request) throws Exception {
HttpHeaders headers = new HttpHeaders();
if (ex instanceof HttpRequestMethodNotSupportedException) {
HttpStatus status = HttpStatus.METHOD_NOT_ALLOWED;
return handleHttpRequestMethodNotSupported((HttpRequestMethodNotSupportedException) ex, headers, status, request);
}
else if (ex instanceof HttpMediaTypeNotSupportedException) {
HttpStatus status = HttpStatus.UNSUPPORTED_MEDIA_TYPE;
return handleHttpMediaTypeNotSupported((HttpMediaTypeNotSupportedException) ex, headers, status, request);
}
//...
}
//...
}
5. DefaultErrorAttributes
5.1要覆盖所有异常的默认JSON错误响应，请创建一个bean并扩展 DefaultErrorAttributes
CustomErrorAttributes.java
package com.zthinker.error;
import org.springframework.boot.web.servlet.error.DefaultErrorAttributes;
import org.springframework.stereotype.Component;
import org.springframework.web.context.request.WebRequest;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Map;
@Component
public class CustomErrorAttributes extends DefaultErrorAttributes {
private static final DateFormat dateFormat = new SimpleDateFormat("yyyy/MM/dd HH:mm:ss");
@Override
public Map<String, Object> getErrorAttributes(WebRequest webRequest, boolean includeStackTrace) {
// Let Spring handle the error first, we will modify later :)
Map<String, Object> errorAttributes = super.getErrorAttributes(webRequest, includeStackTrace);
// format & update timestamp
Object timestamp = errorAttributes.get("timestamp");
if (timestamp == null) {
errorAttributes.put("timestamp", dateFormat.format(new Date()));
} else {
errorAttributes.put("timestamp", dateFormat.format((Date) timestamp));
}
// insert a new key
errorAttributes.put("version", "1.2");
return errorAttributes;
}
}
现在，日期时间已格式化，并且将新字段– version添加到JSON错误响应中。
curl localhost:8080/books/5
{
"timestamp":"2019/02/27 13:34:24",
"status":404,
"error":"Not Found",
"message":"Book id not found : 5",
"path":"/books/5",
"version":"1.2"
}
curl localhost:8080/abc
{
"timestamp":"2019/02/27 13:35:10",
"status":404,
"error":"Not Found",
"message":"No message available",
"path":"/abc",
"version":"1.2"
}