java - 如何使用 Java 从 XML 文件获取属性

Question

我为 Oracle Access Manager 开发了一个身份验证插件

简单来说，它包含:

• java.class
• 以下XML

I'm trying to Dynamically get the <Value> tag of an <Attribute> from the XML file.

<Plugin type="Authentication">
    <author>Phill</author>
    <email>phill@example.com</email>
    <creationDate>12:47:00, 2019-07-11</creationDate>
    <description>Phill-Plugin</description>
    <configuration>
        <AttributeValuePair>
            <Attribute type="string" length="60">GenerateUrl</Attribute>
            <mandatory>true</mandatory>
            <instanceOverride>false</instanceOverride>
            <globalUIOverride>true</globalUIOverride>
            <value>This is the value i'm trying to retrieve</value>
        </AttributeValuePair>
    </configuration>
</Plugin>

<小时/>

java.class

            try {

                CredentialParam tem = context.getCredential().getParam("GenerateUrl");
                String temp = (String) tem.getValue();
                System.out.println("TEST: " + temp);
                generateUrl = temp + "The User" + user;
            } catch (Exception e) {
                System.out.println("\n\n\n-------------------\n");
                System.out.println("-      Input Is:         -\n");
                System.out.println("-       "+e+"            -\n");
                System.out.println("-------------------\n");
                generateUrl = "A URL" + "The User" + user;
            }

重要说明:

The context object is an AuthenticationContext instance containing information about the Plug-in

根据 Oracle 的文档，这正是某人检索 Attribute 的方法。但我总是得到 NullPointerException

有没有其他方法可以检索 <Value> ？

Answer 1

我必须尝试另一种方法并对 XML 进行正确的解析

If you can use external libs here is how:

    public static void main(String[] args) throws ParserConfigurationException, SAXException, IOException {
        File stocks = new File("PhillPlugin.xml");
            DocumentBuilderFactory dbFactory = DocumentBuilderFactory.newInstance();
            DocumentBuilder dBuilder = dbFactory.newDocumentBuilder();
            Document doc = dBuilder.parse(stocks);
            doc.getDocumentElement().normalize();

            NodeList nodes = doc.getElementsByTagName("AttributeValuePair");

            for (int i = 0; i < nodes.getLength(); i++) {
              Node node = nodes.item(i);
              if (node.getNodeType() == Node.ELEMENT_NODE) {
                Element element = (Element) node;
                if(i==0)
                 {
                 tempurlGen=getValue("value",element);
                   System.out.println("GenerateUrl: " + getValue("value", element));
                 }
                 else if (i==1)
                 {
                 tempurlVal=getValue("value",element);
                 System.out.println("ValidateUrl: " + getValue("value", element));
                 }

              }
            }
          }
          static String getValue(String tag, Element element) {
            NodeList nodes = element.getElementsByTagName(tag).item(0).getChildNodes();
            Node node = (Node) nodes.item(0);
            return node.getNodeValue();
          }

If you can't include javax libraries here is how to parse the XML using streams

    public void getXMLData() throws Exception {
        File stocks = new File("PhillPlugin.xml");
        BufferedInputStream in = new BufferedInputStream(new FileInputStream(stocks));
        StringBuilder sb = new StringBuilder();
        int cp;
        while ((cp = in.read()) != -1) {
            sb.append((char) cp);
            String t = sb.toString();
            if (t.contains("</AttributeValuePair>")) {
                String test = sb.toString();
                String test1p[] = test.split("<value>|</value>");
                tempurlGen = test1p[1];
                break;
            }
        }

        sb = new StringBuilder();
        while ((cp = in.read()) != -1) {

            sb.append((char) cp);
            String t = sb.toString();
            if (t.contains("</AttributeValuePair>")) {
                String test = sb.toString();
                String test1p[] = test.split("<value>|</value>");
                tempurlVal = test1p[1];
                break;
            }

        }
    }

确保您定义了 tempurlGen 和 tempurlVal