如何在apache駱駝中拆分json數組

我得到一個json數組作爲基於apache-camel-spark的休息界面的輸入。在開始時，我想分割json數組來通過apache駱駝路線處理每個元素個體。我如何做到這一點？如何在apache駱駝中拆分json數組

我的測試輸入JSON：

[ 
    { 
     "document": { 
     "name": "blub1", 
     "type": "pdf" 
     } 
    }, 
    { 
     "document": { 
     "name": "blub2", 
     "type": "pdf" 
     } 
    } 
];

對於這個問題，我發現了計算器的一些問題，其中描述了這種間接：
link 1，link 2，link 3。

基礎上的例子，我嘗試以下的駱駝路線：

restConfiguration().component("spark-rest").port(8080) 
    .bindingMode(RestBindingMode.json) 
    .dataFormatProperty("prettyPrint", "true"); 

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

from("direct:split") 
    .marshal().json(JsonLibrary.Jackson) 
    .split(new JsonPathExpression("$..document.")).process(new Processor() { 
     public void process(Exchange exchange) throws Exception { 
     String s = exchange.getIn().getBody(String.class); 
     System.out.println(s); 
     } 
    }).to("file:outbox");

當我這樣做，我總是得到以下異常：

錯誤DefaultErrorHandler - 無法交付（的MessageId ：在ExchangeId：[...]）。分娩後試圖耗盡：1 抓：org.apache.camel.ExpressionEvaluationException：顯示java.lang.NullPointerException

我沒有找到原因，什麼黃與我的表情？我改變了它，但我總是得到NullPointerException。

我下載了JavaScript jsonPath library並測試了$..document.表達式，它爲這兩個對象提供了一個數組。我也試了一下駱駝，它說，該表達式被發現在測試輸入JSON（返回true）：

from("direct:testExpression") 
     .marshal().json(JsonLibrary.Jackson) 
     .choice() 
      .when().jsonpath("$..document.", true) 
      .process(new Processor() { 
       public void process(Exchange exchange) throws Exception { 
       String payload = exchange.getIn().getBody(String.class); 
       exchange.getIn().setBody("true"); 
       System.out.println(payload); 
       } 
      }) 
      .to("file:outbox") 
     .otherwise() 
      .process(new Processor() { 
       public void process(Exchange exchange) throws Exception { 
       String payload = exchange.getIn().getBody(String.class); 
       exchange.getIn().setBody("false"); 
       System.out.println(payload); 
       } 
      }) 
      .to("file:outbox");

什麼我錯了，爲什麼我得到的NullPointerException異常？如何分割JSON？

這裏完整堆棧跟蹤：

org.apache.camel.ExpressionEvaluationException: java.lang.NullPointerException 
    at org.apache.camel.jsonpath.JsonPathExpression.evaluate(JsonPathExpression.java:95) ~[camel-jsonpath-2.18.0.jar:2.18.0] 
    at org.apache.camel.support.ExpressionAdapter.evaluate(ExpressionAdapter.java:36) ~[camel-core-2.18.0.jar:2.18.0] 
    at org.apache.camel.processor.Splitter.createProcessorExchangePairs(Splitter.java:113) ~[camel-core-2.18.0.jar:2.18.0] 
    at org.apache.camel.processor.MulticastProcessor.process(MulticastProcessor.java:231) ~[camel-core-2.18.0.jar:2.18.0] 
    at org.apache.camel.processor.Splitter.process(Splitter.java:108) ~[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.CamelInternalProcessor.process(CamelInternalProcessor.java:197) [camel-core-2.18.0.jar:2.18.0] 
    at org.apache.camel.component.direct.DirectProducer.process(DirectProducer.java:62) [camel-core-2.18.0.jar:2.18.0] 
    at org.apache.camel.processor.SendProcessor.process(SendProcessor.java:145) [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] 
Caused by: java.lang.NullPointerException 
    at org.apache.camel.jsonpath.JsonPathExpression.evaluateJsonPath(JsonPathExpression.java:118) ~[camel-jsonpath-2.18.0.jar:2.18.0] 
    at org.apache.camel.jsonpath.JsonPathExpression.evaluate(JsonPathExpression.java:88) ~[camel-jsonpath-2.18.0.jar:2.18.0] 
    ... 31 more

來源

2016-11-30 Zeussi

你如何開始/運行駱駝？我懷疑你沒有正確地做到這一點，並且json表達式並沒有用它的引擎初始化，並且你得到了NPE。 –

嗨@ClausIbsen，非常感謝您的回覆。駱駝開始在駱駝火花中嵌入Jetty，其他路線可通過瀏覽器訪問，例如http：// localhost：8080/v1/users/list。對於這個問題，我發送郵遞員的郵件請求，然後上面顯示的路線被稱爲，我得到NPE。我在一個自己的Thread中啓動了Camel的main.run（），如果這可能有副作用，那麼你的意思是什麼？ – Zeussi

在我的pom.xml中，我設置了工件「camel-jsonpath」。文檔說（http://camel.apache.org/jsonpath.html），這就夠了？ – Zeussi

嘗試創建jsonpath表達類似：

ExpressionBuilder.languageExpression("jsonpath","$..document.")

也放到了你的分裂和嘗試。在做各種條件評估時，我通過這種方式獲得了更多的成功。

來源

2016-11-30 11:30:01

不錯，這解決了我的問題。萬分感謝！ – Zeussi

如何在apache駱駝中拆分json數組

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