java 在 Apache Camel 中这种对 null 体的处理能更优雅吗？
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Can this handling of a null body in Apache Camel be more elegant?
提问by Spina
I'm new to Camel and trying to learn idioms and best practices. I am writing web services which need to handle several different error cases. Here is my error handling and routing:
我是 Camel 的新手，正在尝试学习习语和最佳实践。我正在编写需要处理几种不同错误情况的 Web 服务。这是我的错误处理和路由：
onException(JsonParseException.class).inOut("direct:syntaxError").handled(true);
onException(UnrecognizedPropertyException.class).inOut("direct:syntaxError").handled(true);
// Route service through direct to allow testing.
from("servlet:///service?matchOnUriPrefix=true").inOut("direct:service");
from("direct:service")
.choice()
.when(body().isEqualTo(null))
.inOut("direct:syntaxError")
.otherwise()
.unmarshal().json(lJsonLib, AuthorizationParameters.class).inOut("bean:mybean?method=serviceMethod").marshal().json(lJsonLib);
As you can see, I have special handling (content based routing) to deal with a request with a null body. Is there a way to handle this more elegantly? I'm writing several services of this type and it seems like they could be much cleaner.
如您所见，我有特殊处理（基于内容的路由）来处理具有空正文的请求。有没有办法更优雅地处理这个问题？我正在编写几个这种类型的服务，看起来它们可以更干净。
回答by Henryk Konsek
Using body().isNull()expression in content-based routing to redirect nullmessage to Dead Letter Channelis even more than elegant :) . Please note that message redirected to the DLC will still contain headers so you can easily analyze the reason of delivery failure later on.
body().isNull()在基于内容的路由中使用表达式将null消息重定向到死信通道甚至更优雅:)。请注意，重定向到 DLC 的消息仍将包含标题，以便您稍后可以轻松分析传递失败的原因。
choice().
when(body().isNull()).to("jms:deadLetterChannel").
otherwise().to("jms:regularProcessing").
endChoice();
回答by Claus Ibsen
You can use an interceptor, such as interceptFrom with a when, to check for the empty bod, as there is an example of here: http://camel.apache.org/intercept
您可以使用拦截器，例如interceptFrom with a when，来检查空的bod，因为这里有一个例子：http: //camel.apache.org/intercept
And then use stop to indicate no further processing:
然后使用 stop 表示不再进一步处理：
interceptFrom("servlet*").when(body().isNull()).to("direct:syntaxError").stop();
回答by Christian Schneider
You could use a bean that checks for null and throws an exception in case of null. So you could handle this case in your exception handling.
您可以使用检查 null 并在为 null 的情况下抛出异常的 bean。所以你可以在你的异常处理中处理这种情况。
