我已经构建了一个错误 Controller ,它应该是在我的 Spring REST 服务中捕获异常的“最后一行”。但是,我似乎无法将 POJO 作为响应类型返回。为什么 Jackson 不为这个案子工作?
我的类(class)看起来像:
@RestController
public class CustomErrorController implements ErrorController
{
private static final String PATH = "/error";
@Override
public String getErrorPath()
{
return PATH;
}
@RequestMapping (value = PATH)
public ResponseEntity<WebErrorResponse> handleError(HttpStatus status, HttpServletRequest request)
{
WebErrorResponse response = new WebErrorResponse();
// original requested URI
String uri = String.valueOf(request.getAttribute(RequestDispatcher.FORWARD_REQUEST_URI));
// status code
String code = String.valueOf(request.getAttribute(RequestDispatcher.ERROR_STATUS_CODE));
// status message
String msg = String.valueOf(request.getAttribute(RequestDispatcher.ERROR_MESSAGE));
response.title = "Internal Server Error";
response.type = request.getMethod() + ": " + uri;
response.code = Integer.valueOf(code);
response.message = msg;
// build headers
HttpHeaders headers = new HttpHeaders();
headers.setContentType(MediaType.APPLICATION_JSON_UTF8);
// build the response
return new ResponseEntity<>(response, headers, status);
}
public class WebErrorResponse
{
/**
* The error message.
*/
public String message;
/**
* The status code.
*/
public int code;
/**
* The error title.
*/
public String title;
/**
* The error type.
*/
public String type;
}
这应该有效,但唯一的响应是 Jetty 错误消息 406 - Not Acceptable 。
将响应实体主体类型更改为 String 效果很好。 怎么了?也许这是一个错误?
附言:使用 Spring 4.2.8、Spring Boot 1.3.8。
最佳答案
最终解决方案
在 Google 中多次试错循环和往返之后,我终于找到了满足我要求的解决方案。 Spring 中错误处理的主要问题是由默认行为和小文档引起的。
只用Spring不用Spring Boot是没问题的。但是同时使用两者来构建 Web (REST) 服务就像 hell 。
所以我想分享我的解决方案,以帮助遇到相同问题的每个人...
你需要的是:
- 一个 Spring Java 配置类
- spring 的异常处理程序(使用@ControllerAdvice 并扩展ResponseEntityExceptionHandler)
- 错误 Controller (使用 @Controller 并扩展 AbstractErrorController)
- 通过 Jackson 生成错误响应的简单 POJO(可选)
配置(抠图重要部分)
@Configuration
public class SpringConfig extends WebMvcConfigurerAdapter
{
// ... init stuff if needed
@Override
public void configureContentNegotiation(ContentNegotiationConfigurer configurer)
{
// setup content negotiation (automatic detection of content types)
configurer
// use format parameter and extension to detect mimetype
.favorPathExtension(true).favorParameter(true)
// set default mimetype
.defaultContentType(MediaType.APPLICATION_XML)
.mediaType(...)
// and so on ....
}
/**
* Configuration of the {@link DispatcherServlet} bean.
*
* <p>This is needed because Spring and Spring Boot auto-configuration override each other.</p>
*
* @see <a href="http://stackoverflow.com/questions/28902374/spring-boot-rest-service-exception-handling">
* Stackoverflow - Spring Boot REST service exception handling</a>
*
* @param dispatcher dispatcher servlet instance
*/
@Autowired
@SuppressWarnings ("SpringJavaAutowiringInspection")
public void setupDispatcherServlet(DispatcherServlet dispatcher)
{
// FIX: for global REST error handling
// enable exceptions if endpoint not found (instead of static error page)
dispatcher.setThrowExceptionIfNoHandlerFound(true);
}
/**
* Creates the error properties used to setup the global REST error controller.
*
* <p>Using {@link ErrorProperties} is compliant to base implementation if Spring Boot's
* {@link org.springframework.boot.autoconfigure.web.BasicErrorController}.</p>
*
*
* @return error properties
*/
@Bean
public ErrorProperties errorProperties()
{
ErrorProperties properties = new ErrorProperties();
properties.setIncludeStacktrace(ErrorProperties.IncludeStacktrace.NEVER);
properties.setPath("/error");
return properties;
}
// ...
}
Spring 异常处理程序:
@ControllerAdvice(annotations = RestController.class)
public class WebExceptionHandler extends ResponseEntityExceptionHandler
{
/**
* This function handles the exceptions.
*
* @param e the thrown exception
*
* @return error message as XML-document
*/
@ExceptionHandler (Exception.class)
public ResponseEntity<Object> handleErrorResponse(Exception e)
{
logger.trace("Catching Exception in REST API.", e);
return handleExceptionInternal(e, null, null, null, null);
}
@Override
protected ResponseEntity<Object> handleExceptionInternal(Exception ex,
Object body,
HttpHeaders headers,
HttpStatus status,
WebRequest request)
{
logger.trace("Catching Spring Exception in REST API.");
logger.debug("Using " + getClass().getSimpleName() + " for exception handling.");
// fatal, should not happen
if(ex == null) throw new NullPointerException("empty exception");
// set defaults
String title = "API Error";
String msg = ex.getMessage();
if(status == null) status = HttpStatus.BAD_REQUEST;
// build response body
WebErrorResponse response = new WebErrorResponse();
response.type = ex.getClass().getSimpleName();
response.title = title;
response.message = msg;
response.code = status.value();
// build response headers
if(headers == null) headers = new HttpHeaders();
try {
headers.setContentType(getContentType(request));
}
catch(NullPointerException e)
{
// ignore (empty headers will result in default)
}
catch(IllegalArgumentException e)
{
// return only status code
return new ResponseEntity<>(status);
}
return new ResponseEntity<>(response, headers, status);
}
/**
* Checks the given request and returns the matching response content type
* or throws an exceptions if the requested content type could not be delivered.
*
* @param request current request
*
* @return response content type matching the request
*
* @throws NullPointerException if the request does not an accept header field
* @throws IllegalArgumentException if the requested content type is not supported
*/
private static MediaType getContentType(WebRequest request) throws NullPointerException, IllegalArgumentException
{
String accepts = request.getHeader(HttpHeaders.ACCEPT);
if(accepts==null) throw new NullPointerException();
// XML
if(accepts.contains(MediaType.APPLICATION_XML_VALUE) ||
accepts.contains(MediaType.TEXT_XML_VALUE) ||
accepts.contains(MediaType.APPLICATION_XHTML_XML_VALUE))
return MediaType.APPLICATION_XML;
// JSON
else if(accepts.contains(MediaType.APPLICATION_JSON_VALUE))
return MediaType.APPLICATION_JSON_UTF8;
// other
else throw new IllegalArgumentException();
}
}
以及 Spring Boot 的错误 Controller :
@Controller
@RequestMapping("/error")
public class CustomErrorController extends AbstractErrorController
{
protected final Logger logger = LoggerFactory.getLogger(getClass());
/**
* The global settings for this error controller.
*/
private final ErrorProperties properties;
/**
* Bean constructor.
*
* @param properties global properties
* @param attributes default error attributes
*/
@Autowired
public CustomErrorController(ErrorProperties properties, ErrorAttributes attributes)
{
super(attributes);
this.properties = new ErrorProperties();
}
@Override
public String getErrorPath()
{
return this.properties.getPath();
}
/**
* Returns the configuration properties of this controller.
*
* @return error properties
*/
public ErrorProperties getErrorProperties()
{
return this.properties;
}
/**
* This function handles runtime and application errors.
*
* @param request the incorrect request instance
*
* @return error message as XML-document
*/
@RequestMapping (produces = {MediaType.APPLICATION_JSON_UTF8_VALUE, MediaType.APPLICATION_XML_VALUE})
@ResponseBody
public ResponseEntity<Object> handleError(HttpServletRequest request)
{
logger.trace("Catching Exception in REST API.");
logger.debug("Using {} for exception handling." , getClass().getSimpleName());
// original requested REST endpoint
String endpoint = String.valueOf(request.getAttribute(RequestDispatcher.FORWARD_REQUEST_URI));
// status code
String code = String.valueOf(request.getAttribute(RequestDispatcher.ERROR_STATUS_CODE));
// thrown exception
Exception ex = ((Exception) request.getAttribute(RequestDispatcher.ERROR_EXCEPTION));
if(ex == null) {
ex = new RuntimeException(String.valueOf(request.getAttribute(RequestDispatcher.ERROR_MESSAGE)));
}
// release nested exceptions (we want source exception only)
if(ex instanceof NestedServletException && ex.getCause() instanceof Exception) {
ex = (Exception) ex.getCause();
}
// build response body
WebErrorResponse response = new WebErrorResponse();
response.title = "Internal Server Error";
response.type = ex.getClass().getSimpleName();
response.code = Integer.valueOf(code);
response.message = request.getMethod() + ": " + endpoint+"; "+ex.getMessage();
// build response headers
HttpHeaders headers = new HttpHeaders();
headers.setContentType(getResponseType(request));
// build the response
return new ResponseEntity<>(response, headers, getStatus(request));
}
/*@RequestMapping (produces = {MediaType.APPLICATION_JSON_UTF8_VALUE, MediaType.APPLICATION_XML_VALUE})
public ResponseEntity<Map<String, Object>> handleError(HttpServletRequest request)
{
Boolean stacktrace = properties.getIncludeStacktrace().equals(ErrorProperties.IncludeStacktrace.ALWAYS);
Map<String, Object> r = getErrorAttributes(request, stacktrace);
return new ResponseEntity<Map<String, Object>>(r, getStatus(request));
}*/
/**
* Extracts the response content type from the "Accept" HTTP header field.
*
* @param request request instance
*
* @return response content type
*/
private MediaType getResponseType(HttpServletRequest request)
{
String accepts = request.getHeader(HttpHeaders.ACCEPT);
// only XML or JSON allowed
if(accepts.contains(MediaType.APPLICATION_JSON_VALUE))
return MediaType.APPLICATION_JSON_UTF8;
else return MediaType.APPLICATION_XML;
}
}
就是这样,POJO WebErrorResponse 是一个仅使用公共(public)字符串和 int 字段的普通类。
上述类适用于支持 XML 和 JSON 的 REST API。 工作原理:
- 来自 Controller (自定义和应用程序逻辑)的异常将由 Spring 异常处理程序处理
- 来自 Spring 的异常将由 Spring 异常处理程序处理(例如缺少参数)
- 404(缺少端点)将由 Spring Boot 错误 Controller 处理
- mimetype 问题(例如请求图像/png 但抛出异常)将首先移至 Spring 异常处理程序,然后重定向到 Spring Boot 错误 Controller (由于 mimetype 异常)
我希望这能为像我一样困惑的其他人澄清一些事情。
最好的问候,
压缩包
关于java - Spring Error Controller 响应 Not Acceptable ,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/41616612/