Java DOM setAttribute 不起作用

Question

有人可以告诉我为什么这不起作用吗？这让我发疯。

myFile.xml

<?xml version="1.0" encoding="UTF-8" ?>
<root date="oldValue" />     

Java代码

try {
    Document doc = builder.parse(new File("myFile.xml"));
    Element root = doc.getDocumentElement();
    System.out.println("date: " + root.getAttribute("date") + "\n");
    root.setAttribute("date", "test");
    System.out.println("date: " + root.getAttribute("date"));
}  catch (Exception e)  {
    System.out.println("Something went wrong.");
}

输出

oldValue
oldValue

无论我做什么，我都无法将代码写入 XML 文件...我尝试在根的子节点上执行 setAttribute() 函数。我尝试过删除 root...没有任何作用。我非常沮丧，所以任何帮助将不胜感激。谢谢。

Answer 1

您是否遵循与下面相同的代码？这对我有用(与 myFile.xml 中的内容相同):

public static void main(String... args) throws Exception {
    DocumentBuilder builder = DocumentBuilderFactory.newInstance().newDocumentBuilder();

    try{
        Document doc = builder.parse(new File("myFile.xml"));
        Element root = doc.getDocumentElement();
        System.out.println("date: " + root.getAttribute("date") + "\n");
        root.setAttribute("date", "test");
        System.out.println("date: " + root.getAttribute("date"));
    } catch (Exception e) {
        System.out.println("Something went wrong.");
    }
}