JAVA 修改 XML 文件

Question

我正在尝试从 JAVA 程序修改我的 Config.xml 文件，文件包含有关 MySql 连接的数据。

点击按钮后的代码如下：

        DocumentBuilderFactory domFactory = DocumentBuilderFactory.newInstance();
        File f = new File("Config.xml");
        Document doc = domFactory.newDocumentBuilder().parse(f.getAbsolutePath());

        String url = server_field.getText();
        String user = db_login_field.getText();
        String pass = db_pass_field.getText();
        String baze = db_name_field.getText();

        klases.update_xml(doc, "jdbc/url", url);
        klases.update_xml(doc, "jdbc/username", user);
        klases.update_xml(doc, "jdbc/password", pass);
        klases.update_xml(doc, "jdbc/name", baze);

        TransformerFactory transformerFactory = TransformerFactory.newInstance();
        Transformer tf = transformerFactory.newTransformer();
        DOMSource domSource = new DOMSource(doc);
        try (FileOutputStream fos = new FileOutputStream(f)) {
             StreamResult sr = new StreamResult(fos);
             tf.transform(domSource, sr);
        }

update_xml函数：

public static void update_xml(Document doc, String path, String def) {
    String p[] = path.split("/");
    //search nodes or create them if they do not exist
    Node n = doc;
    for (int i = 0; i < p.length; i++) {
        NodeList kids = n.getChildNodes();
        Node nfound = null;
        for (int j = 0; j < kids.getLength(); j++) {
            if (kids.item(j).getNodeName().equals(p[i])) {
                nfound = kids.item(j);
                break;
            }
        }
        if (nfound == null) {
            nfound = doc.createElement(p[i]);  // LINE 300
            n.appendChild(nfound);
            n.appendChild(doc.createTextNode("\n")); //add whitespace, so the result looks nicer. Not really needed
        }
        n = nfound;
    }
    NodeList kids = n.getChildNodes();
    for (int i = 0; i < kids.getLength(); i++) {
        if (kids.item(i).getNodeType() == Node.TEXT_NODE) {
            //text node exists
            kids.item(i).setNodeValue(def); //override
            return;
        }
    }

    n.appendChild(doc.createTextNode(def));

}

这里是 XML 文件：

<?xml version="1.0" encoding="UTF-8"?>
<jdbc>
    <url>localhost:3306</url>
    <driver>com.mysql.jdbc.Driver</driver>
    <username>username</username>
    <password>password</password>
    <name>database</name>
</jdbc>

这是错误：

Exception in thread "AWT-EventQueue-0" org.w3c.dom.DOMException: INVALID_CHARACTER_ERR: An invalid or illegal XML character is specified. 
at com.sun.org.apache.xerces.internal.dom.CoreDocumentImpl.createElement(CoreDocumentImpl.java:622)
at programa.klases.update_xml(klases.java:300)

第 300 行已评论。等待解决方案，谢谢！

Answer 1

由于路径中的前导 / 字符，p 数组中生成了一个 [space] 字符

您可以从原始路径中删除 /...

update_xml(doc, "jdbc/url", url);
update_xml(doc, "jdbc/username", user);
update_xml(doc, "jdbc/password", pass);
update_xml(doc, "jdbc/name", baze);

这将消除即时错误

Now I didn't get any error, but didn't get any changes in file too.

None 你的示例代码显示你实际上将 Document 保存回文件，一旦加载，DOM 与其来源之间没有关联，您需要自己保存内容，例如...

DOMSource domSource = new DOMSource(doc);
try (FileOutputStream fos = new FileOutputStream(f)) {
    StreamResult sr = new StreamResult(fos);
    tf.transform(domSource, sr);
}

JAVA 修改 XML 文件

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