Java 如何在Jackson封送期间捕获ApacheCamel路由中的JsonParseException？

我通过HTTP-POST向我的Camel Spark REST组件发送一个无效的JSON正文。在我的驼峰路线上，JSON主体将通过Jackson库从JSON转换（封送）为Java对象。封送处理失败，因为JSON正文无效。使用camel doTry/doCatch元素，我尝试捕获异常并自己处理它们。这看起来像这样：

rest("/v1/users")
    .consumes("application/json")
    .produces("application/json")
.post("/insert")
.to("direct:restInput");

from("direct:restInput")
.doTry()
    .marshal().json(JsonLibrary.Jackson)
    [...]
    .process(new Processor() {
        public void process(Exchange exchange) throws Exception {
            //throw new JsonParseException(null, "");
       }
    })
    [...]
.doCatch(JsonParseException.class)
    .process(new Processor() {
        public void process(Exchange exchange) throws Exception {
            System.out.println("JsonParseException occured");
       }
    })
.doCatch(Exception.class)
    .process(new Processor() {
        public void process(Exchange exchange) throws Exception {
            System.out.println("Exception occured");
       }
    })
.end()
.marshal();

如果存在无效的JSON正文，则Jackson封送处理程序将抛出JsonParseException。正如您在上面所看到的，我尝试捕获JsonParseException异常，它应该在我的控制台上输出

JsonParseException Occursed

但是例外情况是未被捕获，我在控制台上获得完整的堆栈跟踪：

Message History
---------------------------------------------------------------------------------------------------------------------------------------
RouteId              ProcessorId          Processor                                                                        Elapsed (ms)
[route4            ] [route4            ] [spark-rest://post:v1/users/insert?accept=application%2Fjson                   ] [        42]
[route4            ] [restBinding4      ] [                                                                              ] [        39]

Stacktrace
    ---------------------------------------------------------------------------------------------------------------------------------------
    com.fasterxml.jackson.core.JsonParseException: Unexpected character (':' (code 58)): was expecting comma to separate Array entries
     at [Source: java.io.ByteArrayInputStream@1aa6eb2; line: 23, column: 17]
        at com.fasterxml.jackson.core.JsonParser._constructError(JsonParser.java:1702) ~[jackson-core-2.8.3.jar:2.8.3]
        at com.fasterxml.jackson.core.base.ParserMinimalBase._reportError(ParserMinimalBase.java:558) ~[jackson-core-2.8.3.jar:2.8.3]
        at com.fasterxml.jackson.core.base.ParserMinimalBase._reportUnexpectedChar(ParserMinimalBase.java:456) ~[jackson-core-2.8.3.jar:2.8.3]
        at com.fasterxml.jackson.core.json.UTF8StreamJsonParser.nextToken(UTF8StreamJsonParser.java:761) ~[jackson-core-2.8.3.jar:2.8.3]
        at com.fasterxml.jackson.databind.deser.std.UntypedObjectDeserializer$Vanilla.mapArray(UntypedObjectDeserializer.java:594) ~[jackson-databind-2.8.3.jar:2.8.3]
        at com.fasterxml.jackson.databind.deser.std.UntypedObjectDeserializer$Vanilla.deserialize(UntypedObjectDeserializer.java:510) ~[jackson-databind-2.8.3.jar:2.8.3]
        at com.fasterxml.jackson.databind.ObjectMapper._readMapAndClose(ObjectMapper.java:3789) ~[jackson-databind-2.8.3.jar:2.8.3]
        at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:2899) ~[jackson-databind-2.8.3.jar:2.8.3]
        at org.apache.camel.component.jackson.JacksonDataFormat.unmarshal(JacksonDataFormat.java:172) ~[camel-jackson-2.18.0.jar:2.18.0]
        at org.apache.camel.processor.UnmarshalProcessor.process(UnmarshalProcessor.java:69) ~[camel-core-2.18.0.jar:2.18.0]
        at org.apache.camel.component.rest.RestConsumerBindingProcessor.process(RestConsumerBindingProcessor.java:189) ~[camel-core-2.18.0.jar:2.18.0]
        at org.apache.camel.management.InstrumentationProcessor.process(InstrumentationProcessor.java:77) ~[camel-core-2.18.0.jar:2.18.0]
        at org.apache.camel.processor.RedeliveryErrorHandler.process(RedeliveryErrorHandler.java:542) [camel-core-2.18.0.jar:2.18.0]
        at org.apache.camel.processor.CamelInternalProcessor.process(CamelInternalProcessor.java:197) [camel-core-2.18.0.jar:2.18.0]
        at org.apache.camel.processor.Pipeline.process(Pipeline.java:120) [camel-core-2.18.0.jar:2.18.0]
        at org.apache.camel.processor.Pipeline.process(Pipeline.java:83) [camel-core-2.18.0.jar:2.18.0]
        at org.apache.camel.processor.CamelInternalProcessor.process(CamelInternalProcessor.java:197) [camel-core-2.18.0.jar:2.18.0]
        at org.apache.camel.processor.DelegateAsyncProcessor.process(DelegateAsyncProcessor.java:97) [camel-core-2.18.0.jar:2.18.0]
        at org.apache.camel.component.sparkrest.CamelSparkRoute.handle(CamelSparkRoute.java:46) [camel-spark-rest-2.18.0.jar:2.18.0]
        at spark.RouteImpl$1.handle(RouteImpl.java:58) [spark-core-2.3.jar:?]
        at spark.webserver.MatcherFilter.doFilter(MatcherFilter.java:162) [spark-core-2.3.jar:?]
        at spark.webserver.JettyHandler.doHandle(JettyHandler.java:61) [spark-core-2.3.jar:?]
        at org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:189) [jetty-server-9.2.19.v20160908.jar:9.2.19.v20160908]
        at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:141) [jetty-server-9.2.19.v20160908.jar:9.2.19.v20160908]
        at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:97) [jetty-server-9.2.19.v20160908.jar:9.2.19.v20160908]
        at org.eclipse.jetty.server.Server.handle(Server.java:499) [jetty-server-9.2.19.v20160908.jar:9.2.19.v20160908]
        at org.eclipse.jetty.server.HttpChannel.handle(HttpChannel.java:311) [jetty-server-9.2.19.v20160908.jar:9.2.19.v20160908]
        at org.eclipse.jetty.server.HttpConnection.onFillable(HttpConnection.java:257) [jetty-server-9.2.19.v20160908.jar:9.2.19.v20160908]
        at org.eclipse.jetty.io.AbstractConnection$2.run(AbstractConnection.java:544) [jetty-io-9.2.19.v20160908.jar:9.2.19.v20160908]
        at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:635) [jetty-util-9.2.19.v20160908.jar:9.2.19.v20160908]
        at org.eclipse.jetty.util.thread.QueuedThreadPool$3.run(QueuedThreadPool.java:555) [jetty-util-9.2.19.v20160908.jar:9.2.19.v20160908]
        at java.lang.Thread.run(Thread.java:745) [?:1.8.0_101]

---

根据我的测试，这种情况发生在

.marshall（）.json（JsonLibrary.Jackson）

部分。如果我发送一个有效的JSON正文，并在第一个处理器中手动抛出JsonParseException（请参见注释行），那么将捕获异常。

Exception.class

catch块也永远不会被调用，因此它可能被排除，我试图捕获“错误”的异常。是否有机会捕获Jackson封送处理程序中的异常，或者是否有检查JSON正文（如果格式正确）的Camel组件，我可以将其放在封送处理程序前面？

异常可能会在端点中抛出，而不是在封送处理步骤中抛出。我不知道spart rest端点，但是对于Jetty端点和rest DSL，编组错误会在Jetty端点本身中抛出。除了堆栈跟踪之外，Camel还应该记录消息历史记录。您可以在历史记录中验证是否执行了编组步骤

2017-01-19 09:11:28,040 | ERROR | qtp762554626-172 | DefaultErrorHandler              | 75 - org.apache.camel.camel-core - 2.16.3 |  | Failed delivery for (MessageId: ID-Ralfs-MacBook-Pro-local-60691-1484813099793-0-2 on ExchangeId: ID-Ralfs-MacBook-Pro-local-60691-1484813099793-0-1). Exhausted after delivery attempt: 1 caught: com.fasterxml.jackson.core.JsonParseException: Unexpected character ('n' (code 110)): was expecting double-quote to start field name
 at [Source: java.io.ByteArrayInputStream@49828827; line: 33, column: 6]

Message History
---------------------------------------------------------------------------------------------------------------------------------------
RouteId              ProcessorId          Processor                                                                        Elapsed (ms)
[route1            ] [route1            ] [jetty:http://0.0.0.0:8282/some/path?httpMethodRestrict=PUT   ] [        15]
[route1            ] [restBinding1      ] [                                                                              ] [        12]

Exchange
---------------------------------------------------------------------------------------------------------------------------------------
Exchange[
    Id                  ID-Ralfs-MacBook-Pro-local-60691-1484813099793-0-1
    ExchangePattern     InOut

[..]

Stacktrace
---------------------------------------------------------------------------------------------------------------------------------------
com.fasterxml.jackson.core.JsonParseException: Unexpected character ('n' (code 110)): was expecting double-quote to start field name
 at [Source: java.io.ByteArrayInputStream@49828827; line: 33, column: 6]
    at com.fasterxml.jackson.core.JsonParser._constructError(JsonParser.java:1581)[55:com.fasterxml.jackson.core.jackson-core:2.6.3]
    at com.fasterxml.jackson.core.base.ParserMinimalBase._reportError(ParserMinimalBase.java:533)[55:com.fasterxml.jackson.core.jackson-core:2.6.3]
    at com.fasterxml.jackson.core.base.ParserMinimalBase._reportUnexpectedChar(ParserMinimalBase.java:462)[55:com.fasterxml.jackson.core.jackson-core:2.6.3]
[..]

如果在端点上确实抛出了异常，那么自定义错误处理的选项取决于您希望执行的错误处理类型

正如您自己所建议的，您可以使用全局

onException

处理程序来使用处理器来处理错误。 如果您只想控制客户端接收的错误消息和http响应代码的类型，那么提供自己的http绑定或请求/响应处理策略可能会更容易。我也不知道spark rest端点，但使用Jetty，您可以提供自己的http绑定实现，如下所示：

public class JettyNoStacktraceHttpBinding extends JettyRestHttpBinding {

    private static final int BAD_REQUEST = 400;

    @Override
    public void doWriteExceptionResponse(Throwable exception, javax.servlet.http.HttpServletResponse response) throws java.io.IOException {
        if (exception instanceof JsonParseException) {
            response.setStatus(BAD_REQUEST);

            response.setContentType("text/plain");
            PrintWriter pw = response.getWriter();
            pw.print(exception.getMessage());
            pw.flush();
        }
    }

}


<restConfiguration contextPath="/some/path" component="jetty" scheme="http" host="0.0.0.0" port="8282" bindingMode="json">
    <endpointProperty key="httpBindingRef" value="jettyNoStackTraceHTTPBinding" />
<!-- ... -->
</restConfiguration>

公共类JettyNoStacktraceHttpBinding扩展了JettyRestHttpBinding{
私有静态最终int BAD_请求=400；
@凌驾
public void doWriteExceptionResponse（Throwable exception，javax.servlet.http.HttpServletResponse）抛出java.io.IOException{
if（JsonParseException的异常实例）{
响应。设置状态（错误的请求）；
response.setContentType（“文本/普通”）；
PrintWriter pw=response.getWriter（）；
print（exception.getMessage（））；
pw.flush（）；
}
}
}

您确定在

.marshall（）.json（JsonLibrary.Jackson）

行上引发了异常吗？我不知道spark rest端点，但是当将jetty端点与rest DSL一起使用时，

com.fasterxml.jackson.core.JsonParseException

在端点本身中引发。不在后续编组步骤中。在stacktrace旁边，您还应该看到日志中的消息历史记录。你能不能也发布这个消息和/或检查历史记录是否包含编组步骤？你说得对@Ralf，我检查了历史记录，它发生在restBinding中。对不起，我完全忽略了那部分。但是不可能将“doTry/doCatch”部分放在.post（“…”）部分之前。所以，我不能使用doTry/doCatch，或者你是如何解决这个问题的？您使用了OneException吗？谢谢@Ralf，还有OneException（JsonParseException.class）.handled（true.to）（“…”）；在全球范围内，它起作用。如果你想以anwser的身份发表你的评论，我会接受它作为“最佳答案”。谢谢你的回答。OneException部分工作正常。我还尝试了您的请求/响应处理程序。我搜索了一个抽象类而不是Jetty，结果发现，org.apache.camel.component.http4 DefaultHttpBinding或HttpBinding中应该有。但在Camel 2.17.3/2.18.0中，它丢失了。我在2.15.0中找到了它。他们是否删除了它并忘记更新文档？如果是的话，现在有什么选择？如果你不知道，我可以问另一个问题。@Zeussi，最好问一个新问题。