Question

我使用通过注释配置的Spring Boot，我遇到了一个异常处理程序会抛出我无法捕获的错误的问题。我想出了如何阻止错误被抛出，但我不知道它为什么会起作用。

@ControllerAdvice
public class MyExceptionAdvice {
    ...snip...
    @ResponseBody
    @ExceptionHandler(HttpMediaTypeNotAcceptableException.class)
    void mediaTypeExceptionHandler(HttpMediaTypeNotAcceptableException e) {
        logger.info("exception: {}", e.getMessage());
    }
}

使用curl curl -v -H "Accept: application/xhtml xml" 'http://localhost:8080/testEndpoint'触发此异常会导致以下内容被记录：

2017-01-24 11:08:20 [http-nio-8080-exec-1] [INFO] MyExceptionAdvice - exception: Could not parse 'Accept' header [application/xhtml xml]: Invalid mime type "application/xhtml xml": Invalid token character ' ' in token "xhtml xml" - 

2017-01-24 11:08:20 [http-nio-8080-exec-1] [WARN] org.springframework.web.servlet.mvc.method.annotation.ExceptionHandlerExceptionResolver - Failed to invoke @ExceptionHandler method: void MyExceptionAdvice.mediaTypeExceptionHandler(javax.servlet.http.HttpServletRequest,org.springframework.web.HttpMediaTypeNotAcceptableException) - org.springframework.web.HttpMediaTypeNotAcceptableException: Could not parse 'Accept' header [application/xhtml xml]: Invalid mime type "application/xhtml xml": Invalid token character ' ' in token "xhtml xml"
    at org.springframework.web.accept.HeaderContentNegotiationStrategy.resolveMediaTypes(HeaderContentNegotiationStrategy.java:59)
    ...snip...

2017-01-24 11:08:20 [http-nio-8080-exec-1] [WARN] org.springframework.web.servlet.mvc.support.DefaultHandlerExceptionResolver - Handling of [org.springframework.web.HttpMediaTypeNotAcceptableException] resulted in Exception - java.lang.IllegalStateException: Cannot call sendError() after the response has been committed
    at org.apache.catalina.connector.ResponseFacade.sendError(ResponseFacade.java:472)
    ...snip...

2017-01-24 11:08:20 [http-nio-8080-exec-1] [ERROR] org.apache.catalina.core.ContainerBase.[Tomcat].[localhost].[/].[dispatcherServlet] - Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Could not parse 'Accept' header [application/xhtml xml]: Invalid mime type "application/xhtml xml": Invalid token character ' ' in token "xhtml xml"] with root cause - org.springframework.web.HttpMediaTypeNotAcceptableException: Could not parse 'Accept' header [application/xhtml xml]: Invalid mime type "application/xhtml xml": Invalid token character ' ' in token "xhtml xml"
    at org.springframework.web.accept.HeaderContentNegotiationStrategy.resolveMediaTypes(HeaderContentNegotiationStrategy.java:59)
    ...snip...

对客户端的响应是乱七八糟的HTML和堆栈跟踪：

<!DOCTYPE html><html><head><title>Apache Tomcat/8.5.6 - Error report</title><style type="text/css">H1 {font-family:Tahoma,Arial,sans-serif;color:white;background-color:#525D76;font-size:22px;} H2 {font-family:Tahoma,Arial,sans-serif;color:white;background-color:#525D76;font-size:16px;} H3 {font-family:Tahoma,Arial,sans-serif;color:white;background-color:#525D76;font-size:14px;} BODY {font-family:Tahoma,Arial,sans-serif;color:black;background-color:white;} B {font-family:Tahoma,Arial,sans-serif;color:white;background-color:#525D76;} P {font-family:Tahoma,Arial,sans-serif;background:white;color:black;font-size:12px;}A {color : black;}A.name {color : black;}.line {height: 1px; background-color: #525D76; border: none;}</style> </head><body><h1>HTTP Status 500 - Could not parse 'Accept' header [application/xhtml xml]: Invalid mime type &quot;application/xhtml xml&quot;: Invalid token character ' ' in token &quot;xhtml xml&quot;</h1><div class="line"></div><p><b>type</b> Exception report</p><p><b>message</b> <u>Could not parse 'Accept' header [application/xhtml xml]: Invalid mime type &quot;application/xhtml xml&quot;: Invalid token character ' ' in token &quot;xhtml xml&quot;</u></p><p><b>description</b> <u>The server encountered an internal error that prevented it from fulfilling this request.</u></p><p><b>exception</b></p><pre>org.springframework.web.HttpMediaTypeNotAcceptableException: Could not parse 'Accept' header [application/xhtml xml]: Invalid mime type &quot;application/xhtml xml&quot;: Invalid token character ' ' in token &quot;xhtml xml&quot;
org.springframework.web.accept.HeaderContentNegotiationStrategy.resolveMediaTypes(HeaderContentNegotiationStrategy.java:59)
...snip...

在使用记录不同的值时，我修改了我的异常处理程序，将Response作为参数。

@ResponseBody
@ExceptionHandler(HttpMediaTypeNotAcceptableException.class)
void mediaTypeExceptionHandler(HttpServletResponse response, HttpMediaTypeNotAcceptableException e) {
    logger.info("exception: {}", e.getMessage());
}

现在相同的卷曲只会导致我首先想到的日志，并且不会在下游触发更多错误。

2017-01-24 11:30:31 [http-nio-8080-exec-1] [INFO] com.example.MyExceptionAdvice - exception: Could not parse 'Accept' header [application/xhtml xml]: Invalid mime type "application/xhtml xml": Invalid token character ' ' in token "xhtml xml" -

客户得到的回应是正确的。

我的问题是为什么？在将响应对象传递给处理程序之前，将响应对象作为参数对上游做了什么？如果没有发生的事情是为什么后续错误发生在下游？感谢。

Answer 1

当spring尝试返回错误消息时，它会使用请求“Accept”标头的媒体类型来查找如何格式化响应。 Spring解析'Accept'标题失败，因为该值的格式无效，抛出了另一个异常，这就是你所看到的。

解您可以使用控制器类或方法上的@Request映射来限制API接受的媒体类型，例如：

import org.springframework.http.MediaType;
@RequestMapping( MediaType.APPLICATION_JSON_VALUE)

如果您这样做，则不应接受具有与指定的媒体类型不同的请求，并且将返回Http 406“Not Acceptable”。因为没有创建内容，所以不应再发生所描述的问题。

Answer 2

从日志消息中查看：“application / xhtml xml”。正确的格式可以是“application / xhtml + xml”。 SpringMVC将在返回控制器方法后检查org.springframework.util.MimeTypeUtils.checkToken（字符串类型）中的“Accept”标头，它将不接受内容类型中的空格并将引发异常。

Spring Boot ExceptionHandler引发更多错误

2 个答案: