如何使用AsyncTask和PublishProgress获取XML
How to get XML using AsyncTask and PublishProgress
我解析 XML 数据并将其放入一个对象中。这需要相当长的时间，我决定使用 AsyncTask 在后台运行它。我的代码几乎和这个例子一模一样：
如何使用 AsyncTask 和 Timer 获取 XML？
不同之处在于我想在我走多远的时候发布Progress。我要发布进度的代码的相关部分：
@Override
public void endElement(String namespaceURI, String localName, String qName) throws SAXException {
if (localName.equalsIgnoreCase("client")) {
clients.addClient(mClient);
// Publish Progress
RotationAwareTask.publishProgress();
mClient = null;
}
}static class RotationAwareTask extends AsyncTask<Void, Void, Void> {
RotationAsync activity = null;
int progress = 0;
private SaxClientsHandler saxClientsHandler;
RotationAwareTask(RotationAsync activity) {
attach(activity);
}
@Override
protected Void doInBackground(Void... unused) {
try {
SAXParserFactory spf = SAXParserFactory.newInstance();
SAXParser sp = spf.newSAXParser();
XMLReader xr = sp.getXMLReader();
saxClientsHandler = new SaxClientsHandler();
xr.setContentHandler(saxClientsHandler);
InputSource mSource = new InputSource( new StringReader( Whmcs.getClientsXml() ) );
xr.parse(mSource);
} catch (Exception e) {
Log.e(TAG, e.getMessage(), e);
}
return(null);
}
@Override
protected void onProgressUpdate(Void... unused) {
if (activity==null) {
Log.w("RotationAsync","onProgressUpdate() skipped – no activity");
}
else {
progress += 5;
activity.updateProgress(progress);
}
}
@Override
protected void onPostExecute(Void unused) {
if (activity == null) {
Log.w("RotationAsync","onPostExecute() skipped – no activity");
}
else {
activity.markAsDone();
}
}
void detach() {
activity = null;
}
void attach(RotationAsync activity) {
this.activity = activity;
}
int getProgress() {
return(progress);
}
}到现在为止，您已经推断出我是新手。与我想做的最接近的研究表明：
http://www.mail-archive.com/android-developers@googlegroups.com/msg79275.html
Yes, that is a bit more complex... Two
approaches:
1) Make AsyncTask implement
org.sax.ContentHandler. That way the
SAX callbacks have direct access to
AsyncTask.publishProgress().
2) Create a delegate so that the
parser has a handle back to AsyncTask
for posting progress updates.
当我尝试上述方法时，我得到：
The method
publishProgress(Progress...) from the
type AsyncTask is
not visible
唉，我怎样才能从 endElement 调用 publicProgress？或者有人可以给我一些如何正确地做到这一点？回顾一下：
我有 XML 数据。
读取数据是一个漫长的操作。
我使用 SAXParser 来获取数据。
在 endElement 方法中，数据被添加到最终将在其他地方使用的对象中。
大多数研究表明我必须使用 AsyncTask 并且我现在正在使用它，因为我有一个来自 Commonsware 的很好的屏幕旋转示例。
问题是我如何更新进度。
编辑：
@Cristian 这里是异步任务：
@Override
public void endElement(String namespaceURI, String localName, String qName) throws SAXException {
if (localName.equalsIgnoreCase("client")) {
clients.addClient(mClient);
// Publish Progress
RotationAwareTask.publishProgress();
mClient = null;
}
}static class RotationAwareTask extends AsyncTask<Void, Void, Void> {
RotationAsync activity = null;
int progress = 0;
private SaxClientsHandler saxClientsHandler;
RotationAwareTask(RotationAsync activity) {
attach(activity);
}
@Override
protected Void doInBackground(Void... unused) {
try {
SAXParserFactory spf = SAXParserFactory.newInstance();
SAXParser sp = spf.newSAXParser();
XMLReader xr = sp.getXMLReader();
saxClientsHandler = new SaxClientsHandler();
xr.setContentHandler(saxClientsHandler);
InputSource mSource = new InputSource( new StringReader( Whmcs.getClientsXml() ) );
xr.parse(mSource);
} catch (Exception e) {
Log.e(TAG, e.getMessage(), e);
}
return(null);
}
@Override
protected void onProgressUpdate(Void... unused) {
if (activity==null) {
Log.w("RotationAsync","onProgressUpdate() skipped – no activity");
}
else {
progress += 5;
activity.updateProgress(progress);
}
}
@Override
protected void onPostExecute(Void unused) {
if (activity == null) {
Log.w("RotationAsync","onPostExecute() skipped – no activity");
}
else {
activity.markAsDone();
}
}
void detach() {
activity = null;
}
void attach(RotationAsync activity) {
this.activity = activity;
}
int getProgress() {
return(progress);
}
}这几乎是这个 Commonsware 示例的完全相同的副本：
https://github.com/commonsguy/cw-android/blob/master/Rotation/RotationAsync/src/com/commonsware/android/rotation/async/RotationAsync.java
如你所见：
saxClientsHandler = new
SaxClientsHandler();
调用存在 endElement 方法的 SaxClientHandler()。我正在尝试从那里发布进度。
@Mayra，您是否建议我将所有 saxClientHandler 代码迁移到 AsyncTask 中？
你在做 RotationAwareTask.publishProgress();publishProgress 不是静态方法，你需要在 RotationAwareTask 的实例上调用它。