Android:AsyncTask，如何更新ProgressDialog增量

我想分析一个网页，并将progressdialog样式水平显示，然后逐字节递增，这是可能的？

试试这样的方法

创建进度对话框。

ProgressDialog mProgressDialog = new ProgressDialog(Your_Activity.this);
mProgressDialog.setMessage("Here you can set a message");
mProgressDialog.setIndeterminate(false);
mProgressDialog.setMax(100);
mProgressDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
mProgressDialog.show();
MyAsyncTask obj = new MyAsyncTask ();
obj.execute("url");

private class MyAsyncTask extends AsyncTask<String, Integer, String>{
    @Override
    protected String doInBackground(String... url) {
        int count;
        try {
            URL url = new URL(url[0]);
            URLConnection connection = url.openConnection();
            connection.connect();
            // this will be useful so that you can show a tipical 0-100% progress bar
            int length = connection.getContentLength();

            // downlod the file
            InputStream input = new BufferedInputStream(url.openStream());
            OutputStream output = new FileOutputStream("/sdcard/file_name.txt");

            byte data[] = new byte[1024];

            long total = 0;

            while ((count = input.read(data)) != -1) {
                total += count;
                // publishing the progress....
                publishProgress((int)(total*100/length));
                output.write(data, 0, count);
            }
            output.flush();
            output.close();
            input.close();
        } catch (Exception e) {}
        return null;
    }
    @Override
    public void onProgressUpdate(String... args){
        mProgressDialog.setProgress(args[0]);
     }
  }
}

<uses-permission android:name="android.permission.INTERNET"></uses-permission>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

您的AsyncTask类。

ProgressDialog mProgressDialog = new ProgressDialog(Your_Activity.this);
mProgressDialog.setMessage("Here you can set a message");
mProgressDialog.setIndeterminate(false);
mProgressDialog.setMax(100);
mProgressDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
mProgressDialog.show();
MyAsyncTask obj = new MyAsyncTask ();
obj.execute("url");

private class MyAsyncTask extends AsyncTask<String, Integer, String>{
    @Override
    protected String doInBackground(String... url) {
        int count;
        try {
            URL url = new URL(url[0]);
            URLConnection connection = url.openConnection();
            connection.connect();
            // this will be useful so that you can show a tipical 0-100% progress bar
            int length = connection.getContentLength();

            // downlod the file
            InputStream input = new BufferedInputStream(url.openStream());
            OutputStream output = new FileOutputStream("/sdcard/file_name.txt");

            byte data[] = new byte[1024];

            long total = 0;

            while ((count = input.read(data)) != -1) {
                total += count;
                // publishing the progress....
                publishProgress((int)(total*100/length));
                output.write(data, 0, count);
            }
            output.flush();
            output.close();
            input.close();
        } catch (Exception e) {}
        return null;
    }
    @Override
    public void onProgressUpdate(String... args){
        mProgressDialog.setProgress(args[0]);
     }
  }
}

<uses-permission android:name="android.permission.INTERNET"></uses-permission>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

私有类MyAsyncTask扩展了AsyncTask{
@凌驾
受保护的字符串doInBackground（字符串…url）{
整数计数；
试一试{
URL=新URL（URL[0]）；
URLConnection=url.openConnection（）；
connection.connect（）；
//这将非常有用，以便您可以显示典型的0-100%进度条
int length=connection.getContentLength（）；
//下载文件
InputStream输入=新的BufferedInputStream（url.openStream（））；
OutputStream output=新文件OutputStream（“/sdcard/file_name.txt”）；
字节数据[]=新字节[1024]；
长总计=0；
而（（计数=输入。读取（数据））！=-1）{
总数+=计数；
//发布进度。。。。
出版进度（整数）（总计*100/长度）；
输出.写入（数据，0，计数）；
}
output.flush（）；
output.close（）；
input.close（）；
}捕获（例外e）{}
返回null；
}
@凌驾
public void onProgressUpdate（字符串…参数）{
mProgressDialog.setProgress（参数[0]）；
}
}
}

您必须在AndroidManifest文件中授予这些权限。

ProgressDialog mProgressDialog = new ProgressDialog(Your_Activity.this);
mProgressDialog.setMessage("Here you can set a message");
mProgressDialog.setIndeterminate(false);
mProgressDialog.setMax(100);
mProgressDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
mProgressDialog.show();
MyAsyncTask obj = new MyAsyncTask ();
obj.execute("url");

private class MyAsyncTask extends AsyncTask<String, Integer, String>{
    @Override
    protected String doInBackground(String... url) {
        int count;
        try {
            URL url = new URL(url[0]);
            URLConnection connection = url.openConnection();
            connection.connect();
            // this will be useful so that you can show a tipical 0-100% progress bar
            int length = connection.getContentLength();

            // downlod the file
            InputStream input = new BufferedInputStream(url.openStream());
            OutputStream output = new FileOutputStream("/sdcard/file_name.txt");

            byte data[] = new byte[1024];

            long total = 0;

            while ((count = input.read(data)) != -1) {
                total += count;
                // publishing the progress....
                publishProgress((int)(total*100/length));
                output.write(data, 0, count);
            }
            output.flush();
            output.close();
            input.close();
        } catch (Exception e) {}
        return null;
    }
    @Override
    public void onProgressUpdate(String... args){
        mProgressDialog.setProgress(args[0]);
     }
  }
}

<uses-permission android:name="android.permission.INTERNET"></uses-permission>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

是的，可以参考此示例链接：谢谢您的回答。如果我想从mysql数据库的url和php页面导入5000条记录，我可以用字节计算JSONArray吗？在这种情况下，如何应用此代码？感谢这个函数：-getJSONArray公共JSONArray getJSONArray（int index）抛出JSONException获取与索引关联的JSONArray。参数：index-索引必须介于0和length（）之间-1。返回：一个JSONArray值。抛出：JSONException-如果索引没有值。或者，如果该值不是JSONArray，并且最后一次使用此代码，但使用此代码我可以知道JSONArray维度（以字节为单位）？在某些URL中，您将始终得到-1，然后使用此代码HttpURLConnection=（HttpURLConnection）URL.openConnection（）；连接。设置请求方法（“HEAD”）；connection.connect（）；int length=connection.getContentLength（）；