Throwing SAXException

Question

与Java一起学习XML解析，并正在测试程序中尝试尝试一下。所有测试系统。分支名称"分别为"。

为了纠正我开始调整，当然会进一步打破该程序。现在，我正在扔一个saxexception（我已经标记了我用评论缩小的行，尽管我不清楚saxexception的含义等）'似乎让她回到以前的状态。

这是现在的代码：

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); }
            }
        }   
    }
}

对saxexception的任何帮助都非常感谢，之后我仍然需要弄清楚为什么"名称"元素返回" null"，但首先是第一件事：）。

更新在评论中显示的是导致Saxexception的原因。但是，控制台仍在显示：

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()

或

childElement.getTextContent()

Answer 1

问题在这里

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

您刚刚创建了StringBuilder（XMLStringBuilder）的空对象，并希望解析该编译器，因此编译器会抛出SAXParseException

但是您确实需要做这个

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

当您appendage字符串包含实际XML信息

或执行此

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); 

希望这会有所帮助！

祝你好运！