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java - 将 soapMessage XML 解析为字符串并在 Java 中使用 XPath 进行搜索

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，然后我将其解析为字符串，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，我会不断获得 NPE，如果我使用 NodeList，我会不断获得 0 列表长度。作为测试，我想得到第一辆车。

肥皂反应：

<?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>

在这里我得到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;
}

在这里，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();
}

在这里，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，我将所有方法合二为一：

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();
}

当我打电话时，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)

进程以退出代码 0 结束

标签： javaxpathsoapasmx

解决方案

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

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();

如果你坚持使用 XPath，那么你可以这样做：

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);

我发现第二种方法过大了，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Car了 XML 序列中的第一个，就像您在问题中尝试做的那样。要进行搜索，Id您可以在第一个示例中循环，break;当您找到您的汽车时，或者分别更新第二个示例中的 XPath 表达式。

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