抛出SAXException

学习使用Java进行xml解析,并且正在测试程序中工作,以便随时进行尝试。 除了childElement返回[name:null]和childElement.getNodeValue()返回null而不是[name:“Branch Name”]和“返回值”之外,所有测试System.out.println()分支名称“。

为了纠正这种情况,我开始进行调整,当然还要进一步破坏程序。 现在,我抛出了一个SAXException(我已经标出了我已经缩小到注释的范围,尽管我没有完全清楚SAXException意味着什么等),当我尝试运行时,我可以似乎没有让她回到她以前的地方。

以下是现在的代码:

package uploaders;

import javax.swing.*;
import javax.xml.parsers.*;
import org.w3c.dom.*;
import org.xml.sax.SAXException;
import java.awt.EventQueue;
import java.io.*;

public class Test {
    public static void main(String[] args) throws ParserConfigurationException, SAXException, IOException { 
        JFileChooser chooser = new JFileChooser();
        DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
        DocumentBuilder builder = factory.newDocumentBuilder();
        StringBuilder xmlStringBuilder = new StringBuilder();
        String appendage = "<?xml version="1.0"?><branch0><name>Branch Name</name></branch0>";
        ByteArrayInputStream input = new ByteArrayInputStream(xmlStringBuilder.toString().getBytes("UTF-8"));

        chooser.setCurrentDirectory(new File("."));
        chooser.setMultiSelectionEnabled(false);
        chooser.setFileSelectionMode(JFileChooser.FILES_AND_DIRECTORIES);

        int result = chooser.showOpenDialog(null);

        if (result == JFileChooser.APPROVE_OPTION) { 
            System.out.println("Test Results:");
            System.out.println();
            System.out.println(chooser.getSelectedFile().getPath()); 

            Document doc = builder.parse(input); //originally org.w3c.dom.Document...this line is where SAXException is thrown.
            Element root = doc.getDocumentElement(); 
            NodeList children = root.getChildNodes();

            System.out.println(root.getTagName());
            xmlStringBuilder.append(appendage); //forgot to move this up too (thanks @Vihar)

            for (int i = 0; i < children.getLength(); i++) {
                Node child = children.item(i);
                if (child instanceof Element) { 
                    Element childElement = (Element) child; 
                    System.out.println(childElement.getTagName());
                    System.out.println(childElement.getNodeValue());
                    System.out.println(childElement); }
            }
        }   
    }
}

任何有关SAXException的帮助都非常感谢,之后我仍然可能需要弄清楚为什么“name”元素返回“null”,但首先要做的事情是:)。

更新在注释中显示什么导致了SAXException。 控制台仍然显示这个:

Test Results:

/Users/.../Documents/java/Test/./bin
branch0
name
null           //I'm expecting "Branch Name"
[name: null]   //and "[name: Branch Name]"

最后

childElement.getNodeValue() //needed + .toString() to work or:
childElement.getNodeValue().toString()

要么

childElement.getTextContent()

问题在于此

ByteArrayInputStream input = new ByteArrayInputStream(xmlStringBuilder.toString().getBytes("UTF-8"));

你刚刚创建了一个StringBuilder(xmlStringBuilder)的空对象,并期望解析它,所以编译器会抛出一个SAXParseException

但你真的需要这样做

ByteArrayInputStream input = new ByteArrayInputStream(appendage.toString().getBytes("UTF-8"));

因为你的appendage字符串包含了实际的xml信息

或者这样做

xmlStringBuilder.append(appendage);   //I have just changed the sequence of these lines in your code
ByteArrayInputStream input = new ByteArrayInputStream(xmlStringBuilder.toString().getBytes("UTF-8"));
Document doc = builder.parse(input); 

希望这可以帮助!

祝你好运!

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