将soapMessage XML 解析为String 并在Java 中使用XPath 进行搜索

编程问答 2022-04-28

问题描述

我有一个我无法解决的问题。 我有从 Web 服务获得的 SOAP 响应，然后将其解析为 String，然后将其传递给我想通过 id 查找汽车的方法。 如果我使用 Node，我经常得到 NPE，如果我使用 NodeList，我总是得到 0 列表长度。 作为测试，我想得到第一辆车。

SoapResponse：

<?xml version="1.0" encoding="UTF-8"?>
<soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
   <soap:Body>
      <ShowAllCarsResponse xmlns="http://tempuri.org/">
         <ShowAllCarsResult>
            <Car>
               <Id>1</Id>
               <Make>Mercedes-Benz</Make>
               <Model>C63 AMG</Model>
               <YearOfMake>2007</YearOfMake>
               <Horsepower>450</Horsepower>
               <displacement>6300</displacement>
            </Car>
            <Car>
               <Id>2</Id>
               <Make>Lexus</Make>
               <Model>LC 500</Model>
               <YearOfMake>2020</YearOfMake>
               <Horsepower>471</Horsepower>
               <displacement>5000</displacement>
            </Car>
            <Car>
               <Id>3</Id>
               <Make>Ferrari</Make>
               <Model>488 GTB</Model>
               <YearOfMake>2018</YearOfMake>
               <Horsepower>661</Horsepower>
               <displacement>3900</displacement>
            </Car>
            <Car>
               <Id>4</Id>
               <Make>Rimac</Make>
               <Model>Concept Two</Model>
               <YearOfMake>2021</YearOfMake>
               <Horsepower>1914</Horsepower>
               <displacement>0</displacement>
            </Car>
         </ShowAllCarsResult>
      </ShowAllCarsResponse>
   </soap:Body>
</soap:Envelope>

这里我收到了soapMessage：

private static SOAPMessage createSOAPRequest() throws Exception {
    MessageFactory messageFactory = MessageFactory.newInstance();
    SOAPMessage soapMessage = messageFactory.createMessage();
    SOAPPart soapPart = soapMessage.getSOAPPart();

    String serverURI = "http://www.w3.org/2001/XMLSchema";

    SOAPEnvelope envelope = soapPart.getEnvelope();
    envelope.addNamespaceDeclaration("xsd",serverURI);

    SOAPBody body = soapMessage.getSOAPBody();
    QName bodyName = new QName("http://tempuri.org/","ShowAllCars" );
    MimeHeaders headers = soapMessage.getMimeHeaders();
    headers.addHeader("SOAPAction","http://tempuri.org/" + "ShowAllCars");
    soapMessage.saveChanges();

    return soapMessage;
}

这里我将其解析为字符串：

private static String parseXmlToString(SOAPMessage soapMessage) {
    final StringWriter sw = new StringWriter();
    try {
        TransformerFactory.newInstance().newTransformer().transform(
                new DOMSource(soapMessage.getSOAPPart()),new StreamResult(sw));
    } catch (TransformerException e) {
        throw new RuntimeException(e);
    }
    return sw.toString();
}

这里我尝试使用 XPath 搜索该字符串：

private static void findCarById(String xml) {
    XPath xpath = XPathFactory.newInstance().newXPath();
    System.out.println(xml);
    Document document;
    try {
        DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
        DocumentBuilder db = dbf.newDocumentBuilder();
        document = db.parse(new ByteArrayInputStream(xml.getBytes()));
    } catch (ParserConfigurationException | SAXException | IOException e) {
        e.printstacktrace();
        return;
    }
    String expression = "soap:Envelope/soap:Body/ShowAllCarsResponse/ShowAllCarsResult/Car[1]";
    try {
        NodeList result = (NodeList) xpath.compile(expression).evaluate(document,XPathConstants.NODESET);
        System.out.println("RESULT");
        System.out.println(result.item(0).getTextContent());
    } catch (XPathExpressionException e) {
        e.printstacktrace();
    }
}

作为最后一步，我在一个方法中调用所有方法：

private static void createSoapEnvelope() throws Exception {
    SOAPConnectionFactory soapConnectionFactory = SOAPConnectionFactory.newInstance();
    SOAPConnection soapConnection = soapConnectionFactory.createConnection();

    String url = "http://localhost:49883/CaRSService.asmx";
    SOAPMessage soapResponse = soapConnection.call(createSOAPRequest(),url);

    String xml = parseXmlToString(soapResponse);
    findCarById(xml);

    soapConnection.close();
}

当我打电话给System.out.println(result.item(0).getTextContent()); 我得到：

java.lang.NullPointerException
at hr.algebra.controllers.soAPController.findCarById(SOAPController.java:117)
at hr.algebra.controllers.soAPController.createSoapEnvelope(SOAPController.java:39)
at hr.algebra.controllers.soAPController.btnSearchpressed(SOAPController.java:125)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at sun.reflect.misc.Trampoline.invoke(MethodUtil.java:72)
at sun.reflect.GeneratedMethodAccessor1.invoke(UnkNown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at sun.reflect.misc.MethodUtil.invoke(MethodUtil.java:276)
at javafx.fxml.FXMLLoader$MethodHandler.invoke(FXMLLoader.java:1771)
at javafx.fxml.FXMLLoader$ControllerMethodEventHandler.handle(FXMLLoader.java:1657)
at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:86)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:238)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:191)
at com.sun.javafx.event.CompositeEventdispatcher.dispatchBubblingEvent(CompositeEventdispatcher.java:59)
at com.sun.javafx.event.BasicEventdispatcher.dispatchEvent(BasicEventdispatcher.java:58)
at com.sun.javafx.event.EventdispatchChainImpl.dispatchEvent(EventdispatchChainImpl.java:114)
at com.sun.javafx.event.BasicEventdispatcher.dispatchEvent(BasicEventdispatcher.java:56)
at com.sun.javafx.event.EventdispatchChainImpl.dispatchEvent(EventdispatchChainImpl.java:114)
at com.sun.javafx.event.BasicEventdispatcher.dispatchEvent(BasicEventdispatcher.java:56)
at com.sun.javafx.event.EventdispatchChainImpl.dispatchEvent(EventdispatchChainImpl.java:114)
at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74)
at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:49)
at javafx.event.Event.fireEvent(Event.java:198)
at javafx.scene.Node.fireEvent(Node.java:8411)
at javafx.scene.control.Button.fire(Button.java:185)
at com.sun.javafx.scene.control.behavior.ButtonBehavior.mouseReleased(ButtonBehavior.java:182)
at com.sun.javafx.scene.control.skin.BehaviorSkinBase$1.handle(BehaviorSkinBase.java:96)
at com.sun.javafx.scene.control.skin.BehaviorSkinBase$1.handle(BehaviorSkinBase.java:89)
at com.sun.javafx.event.CompositeEventHandler$normalEventHandlerRecord.handleBubblingEvent(CompositeEventHandler.java:218)
at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:80)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:238)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:191)
at com.sun.javafx.event.CompositeEventdispatcher.dispatchBubblingEvent(CompositeEventdispatcher.java:59)
at com.sun.javafx.event.BasicEventdispatcher.dispatchEvent(BasicEventdispatcher.java:58)
at com.sun.javafx.event.EventdispatchChainImpl.dispatchEvent(EventdispatchChainImpl.java:114)
at com.sun.javafx.event.BasicEventdispatcher.dispatchEvent(BasicEventdispatcher.java:56)
at com.sun.javafx.event.EventdispatchChainImpl.dispatchEvent(EventdispatchChainImpl.java:114)
at com.sun.javafx.event.BasicEventdispatcher.dispatchEvent(BasicEventdispatcher.java:56)
at com.sun.javafx.event.EventdispatchChainImpl.dispatchEvent(EventdispatchChainImpl.java:114)
at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74)
at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:54)
at javafx.event.Event.fireEvent(Event.java:198)
at javafx.scene.Scene$MouseHandler.process(Scene.java:3757)
at javafx.scene.Scene$MouseHandler.access$1500(Scene.java:3485)
at javafx.scene.Scene.impl_processMouseEvent(Scene.java:1762)
at javafx.scene.Scene$ScenePeerListener.mouseEvent(Scene.java:2494)
at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:394)
at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:295)
at java.security.AccessController.doPrivileged(Native Method)
at com.sun.javafx.tk.quantum.GlassViewEventHandler.lambda$handleMouseEvent$2(GlassViewEventHandler.java:432)
at com.sun.javafx.tk.quantum.QuantumToolkit.runWithoutRenderLock(QuantumToolkit.java:389)
at com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(GlassViewEventHandler.java:431)
at com.sun.glass.ui.View.handleMouseEvent(View.java:555)
at com.sun.glass.ui.View.notifyMouse(View.java:937)
at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
at com.sun.glass.ui.win.WinApplication.lambda$null$3(WinApplication.java:177)
at java.lang.Thread.run(Thread.java:748)

进程结束，退出代码 0

解决方法

既然您已经在使用 SAAJ 进行调用，为什么不使用相同的 API 来读取响应？

 df = df.groupby("some_id").apply(lambda x:  x.sample(n = 100) if (x.shape[0]>99) else x)

如果你坚持使用 XPath，那么你可以这样做：

SOAPMessage soapResponse = soapConnection.call(createSOAPRequest(),url);

String ns = "http://tempuri.org/";
SOAPBody responseBody = soapResponse.getSOAPBody();

SOAPElement allCarsResponse = (SOAPElement) responseBody.getElementsByTagNameNS(ns,"ShowAllCarsResponse").item(0);
SOAPElement allCarsResult = (SOAPElement) allCarsResponse.getElementsByTagNameNS(ns,"ShowAllCarsResult").item(0);
NodeList allCars = allCarsResult.getElementsByTagNameNS(ns,"Car");

SOAPElement firstCar = (SOAPElement) allCars.item(0);
String id = firstCar.getElementsByTagNameNS(ns,"Id").item(0).getTextContent();

我觉得第二种方法太过分了，因为您可以通过从一个元素到另一个元素来遍历 API。

我刚刚采用了 XML 序列中的第一个 SOAPMessage soapResponse = soapConnection.call(createSOAPRequest(),url); NamespaceContext nsContext = new NamespaceContext() { @Override public Iterator getPrefixes(String namespaceURI) { return null; } @Override public String getPrefix(String namespaceURI) { return "http://tempuri.org/".equals(namespaceURI) ? "tmp" : null; } @Override public String getNamespaceURI(String prefix) { return "tmp".equals(prefix) ? "http://tempuri.org/" : null; } }; SOAPBody responseBody = soapResponse.getSOAPBody(); Document document = responseBody.extractContentAsDocument(); XPath xpath = XPathFactory.newInstance().newXPath(); xpath.setNamespaceContext(nsContext); XPathExpression expr = xpath .compile("/tmp:ShowAllCarsResponse/tmp:ShowAllCarsResult/tmp:Car[1]/tmp:Id"); String id = expr.evaluate(document); ，就像您在问题中尝试做的那样。要按 Car 进行搜索，您可以在第一个示例中循环，当您找到汽车时可以在 Id 中循环，或者分别更新第二个示例中的 XPath 表达式。

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