使用 XmlPullParser修改 xml 属性值

Question

我有一个XML（实际上是一个String），我想找到所有包含属性width和height的标签，并修改它们的值。

XML 示例：

<div>
<div class="separator" style="clear: both; text-align: center;">
    <a href="http://1.bp.blogspot.com/-b5iKjQ5ivZQ/VOoBX9NinU3232I/AAAAAAAADZU332/zq3apERWFms/s800/IMG_3426.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;">
        <img border="0" height="426" src="http://1.bp.blogspot.com/-b5iKjQ5ivZQ/VOoBX9NinUI/AAAAAAAADZU/zq32323apERWFms/s800/IMG_3426.JPG" width="640" />
    </a>
</div>
<div class="separator" style="clear: both; text-align: center;">
    <iframe allowfullscreen="" frameborder="0" height="315" src="https://www.youtube.com/embed/sI9Qf7UmXl0" width="420"></iframe>
</div>

在上面的例子中，我想修改：

• 426 和 640 值
• 560 和 315 值

我能够使用 XmlPullParser 识别一些值：下面的代码识别 426 和 640 个值，但不能识别 560 和 315。我也不知道如何在XML中修改它们：

public void parse(String inputString) throws XmlPullParserException, IOException {
    XmlPullParser parser = Xml.newPullParser();
    parser.setFeature(XmlPullParser.FEATURE_PROCESS_NAMESPACES, false);
    parser.setInput(new StringReader(inputString));
    parser.nextTag();
    readXml(parser);
}
private void readXml(XmlPullParser parser) throws XmlPullParserException, IOException {
    int eventType = parser.getEventType();
    while (eventType != XmlPullParser.END_DOCUMENT) {
        switch (eventType) {
            case XmlPullParser.START_TAG:
                break;
            case XmlPullParser.END_TAG:
                String h = parser.getAttributeValue(null, "height");
                String w = parser.getAttributeValue(null, "width");
                if (!TextUtils.isEmpty(h) && !TextUtils.isEmpty(w)) {
                    // TODO: need to change here h and w values in XML
                }
                break;
        }
        eventType = parser.next();
    }
}

Answer 1

XmlPullParser 不能修改值。您需要同时解析和写入。同时使用 DomDocument 或基于流的读取器和编写器。

DomDocument最适合您。

Answer 2

这是所需的解决方案。我用 JAVA 写了这个，但你可以在 android 中使用它，只需稍作更改。由于您没有写出要对文件进行哪些更改，因此我假设乘以 2，但您也可以更改它：

private static Document doc = null;
public static void main(String[] args) {
    try {   
        String s = "<File>n" +
                "<div class="separator" style="clear: both; text-align: center;">n" +
                "    <a href="http://1.bp.blogspot.com/-b5iKjQ5ivZQ/VOoBX9NinU3232I/AAAAAAAADZU332/zq3apERWFms/s800/IMG_3426.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;">n" +
                "        <img border="0" height="426" src="http://1.bp.blogspot.com/-b5iKjQ5ivZQ/VOoBX9NinUI/AAAAAAAADZU/zq32323apERWFms/s800/IMG_3426.JPG" width="640" />n" +
                "    </a>n" +
                "</div>n" +
                "<div class="separator" style="clear: both; text-align: center;">n" +
                "    <iframe allowfullscreen="" frameborder="0" height="315" src="https://www.youtube.com/embed/sI9Qf7UmXl0" width="420"></iframe>n" +
                "</div>n" +
                "</File>";
         InputStream stream = new ByteArrayInputStream(s.getBytes(StandardCharsets.UTF_8));
         DocumentBuilderFactory dbFactory 
            = DocumentBuilderFactory.newInstance();
         DocumentBuilder dBuilder = dbFactory.newDocumentBuilder();
         doc = dBuilder.parse(stream);
         doc.getDocumentElement().normalize();
         Element root = doc.getDocumentElement();
         //First, browse the children and modify the required attributes
         browseChildNodesAndModifyValue(root);
         //Now, write to a file, or do something with it
         writeDomToFile();
      } catch (Exception e) {
         e.printStackTrace();
      }

}
private static void browseChildNodesAndModifyValue(Node parent){
    NodeList nodeList = parent.getChildNodes();
    if(nodeList.getLength() > 0){
        for(int temp = 0; temp< nodeList.getLength(); temp++){
            Node node = nodeList.item(temp);
            browseChildNodesAndModifyValue(node);
        }
    }else{
        NamedNodeMap nodeMap = parent.getAttributes();
        if(nodeMap == null) return;
        for(int temp2=0; temp2< nodeMap.getLength(); temp2++){
            Node n = nodeMap.item(temp2);
            String attributeName = n.getNodeName();
            if(attributeName.equals("height")){
                int height = Integer.parseInt(n.getNodeValue());
                System.out.println("Height = "+height);
                //Modify the height here. e.g. I will multiply by 2
                n.setNodeValue(String.valueOf(height*2));
            }else if(attributeName.equals("width")){
                int width = Integer.parseInt(n.getNodeValue());
                System.out.println("width = "+width);
                //Modify the width here. e.g. I will multiply by 2
                n.setNodeValue(String.valueOf(width*2));
            }
        }
    }
}
private static void writeDomToFile() throws TransformerException{
    TransformerFactory transformerfactory=
            TransformerFactory.newInstance();
    Transformer transformer=
            transformerfactory.newTransformer();
    DOMSource source=new DOMSource(doc);
    StreamResult result=new StreamResult(new File("C:\abc.xml"));
    /*
     * For Android, you can use this :
        FileOutputStream _stream=getApplicationContext().openFileOutput("NewDom.xml", getApplicationContext().MODE_WORLD_WRITEABLE);
        StreamResult result=new StreamResult(_stream);
     */
    transformer.transform(source, result);
}

我收到的输出文件是：

<File>
<div class="separator" style="clear: both; text-align: center;">
    <a href="http://1.bp.blogspot.com/-b5iKjQ5ivZQ/VOoBX9NinU3232I/AAAAAAAADZU332/zq3apERWFms/s800/IMG_3426.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;">
        <img border="0" height="852" src="http://1.bp.blogspot.com/-b5iKjQ5ivZQ/VOoBX9NinUI/AAAAAAAADZU/zq32323apERWFms/s800/IMG_3426.JPG" width="1280"/>
    </a>
</div>
<div class="separator" style="clear: both; text-align: center;">
    <iframe allowfullscreen="" frameborder="0" height="630" src="https://www.youtube.com/embed/sI9Qf7UmXl0" width="840"/>
</div>
</File>