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如何为下载提供进度条？

发布于 2024-10-21 16:27:32 字数 92 浏览 3 评论 0原文

在我的应用程序中，我正在下载一个视频文件。我想显示下载的进度条。

通过 AsyncTask 概念怎么可能呢？

谢谢，

尼基

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℡寂寞咖啡 2024-10-28 16:27:32

使用AsyncTask的onProgressUpdate方法。

如果您知道文件的大小，您可以在 onPreExecute 中设置最大值：

protected void onPreExecute() {
  ProgressDialog myDialog = new ProgressDialog(context);
  myDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
  myDialog.setMax(maxValue);
  myDialog.show();
}

编辑：添加 myDialog.show();

有几种方法可以更新进度，可以通过增加一定量或将进度设置为特定值：

@Override
protected void onProgressUpdate(Integer... progress) {
  myDialog.incrementProgressBy(progress[0]);

  // or
  // myDialog.setProgress(progress[0]);

}

然后在 onDoInBackground():

@Override
protected void doInBackGround() {
  // your code
  publishProgress(1);
}

编辑布局中带有进度条的示例：

在布局文件中，添加一个像这样的进度条

<ProgressBar
    android:id="@+id/progressbar"
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    style="?android:attr/progressBarStyleHorizontal"
    android:visibility="gone"
    />

并且在你的异步任务中：

protected void onPreExecute() {
  ProgressBar myProgress = findViewById(R.id.progressbar);
  myProgress.setMax(maxValue);
  myProgress.setVisibility(View.VISIBLE);
}

protected void onProgressUpdate(Integer... progress) {
  myProgress.setProgress(progress[0]);
}

Use the onProgressUpdate method of AsyncTask.

If you know the size of the file you can set the max value in onPreExecute:

protected void onPreExecute() {
  ProgressDialog myDialog = new ProgressDialog(context);
  myDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
  myDialog.setMax(maxValue);
  myDialog.show();
}

EDIT: added myDialog.show();

There are several methods to update the progress, either by incrementing by an amount or by setting the progress to a specific value:

@Override
protected void onProgressUpdate(Integer... progress) {
  myDialog.incrementProgressBy(progress[0]);

  // or
  // myDialog.setProgress(progress[0]);

}

Then in the onDoInBackground():

@Override
protected void doInBackGround() {
  // your code
  publishProgress(1);
}

EDIT example with progressbar in layout:

In your layout file, add a progressbar like this

<ProgressBar
    android:id="@+id/progressbar"
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    style="?android:attr/progressBarStyleHorizontal"
    android:visibility="gone"
    />

And in your asynctask:

protected void onPreExecute() {
  ProgressBar myProgress = findViewById(R.id.progressbar);
  myProgress.setMax(maxValue);
  myProgress.setVisibility(View.VISIBLE);
}

protected void onProgressUpdate(Integer... progress) {
  myProgress.setProgress(progress[0]);
}

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月竹挽风 2024-10-28 16:27:32

首先你必须计算下载时间，然后根据时间限制实现进度条。这里我附上了进度条的示例程序

new Thread(new Runnable() {
         public void run() {
             while (mProgressStatus < 100) {
                 mProgressStatus = doWork();

                 // Update the progress bar
                 mHandler.post(new Runnable() {
                     public void run() {
                         mProgress.setProgress(mProgressStatus);
                     }
                 });

这是用于计算下载文件的时间长度的代码

//once the connection has been opened

List value = urlConnection.getHeaderFields().get("content-Length") if (values != null && !values.isEmpty()) {

// getHeaderFields() returns a Map with key=(String) header 
// name, value = List of String values for that header field. 
// just use the first value here.
String sLength = (String) values.get(0);

if (sLength != null) {
   //parse the length into an integer...
   }

First you have to calculate downloading timi, and then implement progress bar as per time limit. here i enclosed the sample program of progress bar

new Thread(new Runnable() {
         public void run() {
             while (mProgressStatus < 100) {
                 mProgressStatus = doWork();

                 // Update the progress bar
                 mHandler.post(new Runnable() {
                     public void run() {
                         mProgress.setProgress(mProgressStatus);
                     }
                 });

And this is the code for calculating the Time length for downloading file

//once the connection has been opened

List values = urlConnection.getHeaderFields().get("content-Length") if (values != null && !values.isEmpty()) {

// getHeaderFields() returns a Map with key=(String) header 
// name, value = List of String values for that header field. 
// just use the first value here.
String sLength = (String) values.get(0);

if (sLength != null) {
   //parse the length into an integer...
   }

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