在 GZIP 解压过程中设置 ProgressBar maxValue 和 publishProgress 值
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【中文标题】在 GZIP 解压过程中设置 ProgressBar maxValue 和 publishProgress 值【英文标题】:Set ProgressBar maxValue and publishProgress values during GZIP decompressing 【发布时间】:2017-04-01 17:18:27 【问题描述】:我有一个 AsyncTask 正在执行解压缩 GZIP 文件的工作。我刚刚了解到我可以发布 AsyncTasks 的进度,并且成功地设法让它与我之前创建的其他 AsyncTasks 一起工作。我知道要做到这一点,需要 2 个重要值,最大值和当前进度值。
我的问题是我不确定如何从输入流中检索这些值。我当前的 AsyncTask 如下所示:
package com.wizzkidd.myapp.asynctasks;
import android.content.Context;
import android.os.AsyncTask;
import android.util.Log;
import android.view.View;
import android.widget.ProgressBar;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.zip.GZIPInputStream;
public class DecompressGzipAsync extends AsyncTask<String, Integer, Boolean>
ProgressBar progressBar;
private Context _context;
private View _view;
private String _compressedFilePath;
private String _uncompressedFilePath;
public DecompressGzipAsync(Context context, View view, String compressedFilePath)
this._context = context;
this._view = view;
this._compressedFilePath = compressedFilePath;
this._uncompressedFilePath = compressedFilePath.substring(0, compressedFilePath.lastIndexOf(".")); //path + filename without gz extension
@Override
protected void onPreExecute()
super.onPreExecute();
@Override
protected Boolean doInBackground(String... strings)
Boolean isSuccess = false;
byte[] buffer = new byte[1024];
try
GZIPInputStream gzis = new GZIPInputStream(new FileInputStream(_compressedFilePath));
FileOutputStream out = new FileOutputStream(_uncompressedFilePath);
//FIXME: I think I need the file size here?
//progressBar.setMax(???);
int len;
while ((len = gzis.read(buffer)) > 0)
out.write(buffer, 0, len);
//FIXME: I'm not sure what incrementing value can I put in here?
//publishProgress(???);
gzis.close();
out.close();
isSuccess = true;
catch (IOException ex)
ex.printStackTrace();
return isSuccess;
@Override
protected void onProgressUpdate(Integer... values)
super.onProgressUpdate(values);
int currentValue = values[0];
int maxValue = progressBar.getMax();
Log.v("TAG", "Decompressing Progress... currentValue: " + currentValue + " | maxValue: " + maxValue);
@Override
protected void onPostExecute(Boolean result)
super.onPostExecute(result);
if (result)
Log.v("TAG", "Decompressing - Completed");
else
Log.v("TAG", "Decompressing - Failed");
我在我的代码中评论了我认为我需要找到值的地方,但在这里需要一些帮助。任何帮助表示赞赏。
【问题讨论】:
【参考方案1】:根据this post,文件的最后四个字节包含未压缩的文件大小(这意味着限制为 4GB)。
所以这应该有效:
@Override
protected Boolean doInBackground(String... strings)
Boolean isSuccess = false;
byte[] buffer = new byte[1024];
try
RandomAccessFile raf = new RandomAccessFile(new File(_compressedFilePath), "r");
raf.seek(raf.length() - 4);
int b4 = raf.read();
int b3 = raf.read();
int b2 = raf.read();
int b1 = raf.read();
int uncompressedSize = ((0xFF & b1) << 24) | ((0xFF & b2) << 16) |
((0xFF & b3) << 8) | (0xFF & b4);
raf.close();
GZIPInputStream gzis = new GZIPInputStream(new FileInputStream(_compressedFilePath));
FileOutputStream out = new FileOutputStream(_uncompressedFilePath);
int count = 0;
int len;
while ((len = gzis.read(buffer)) > 0)
out.write(buffer, 0, len);
count += len;
publishProgress(count, uncompressedSize);
gzis.close();
out.close();
isSuccess = true;
catch (IOException ex)
Log.e("DecompressGzipAsync", "error unzipping file", ex);
return isSuccess;
@Override
protected void onProgressUpdate(Integer... values)
super.onProgressUpdate(values);
int count = values[0];
int uncompressedSize = values[1];
int maxValue = progressBar.getMax();
int progress = (int) ((float) count / (float) uncompressedSize * maxValue);
if (progress > maxValue) progress = maxValue; // sanity check
progressBar.setProgress(progress);
Log.v("DecompressGzipAsync", "Decompressing Progress... currentValue: " + progress + " | maxValue: " + maxValue);
【讨论】:
谢谢@kris,您不仅提供了答案,而且还进一步将答案实现到我现有的代码中。现在,如果那不是勺子喂食,我不知道是什么。非常感谢! 当它复制/粘贴一堆代码并更改几行时,我很乐意这样做。 :)以上是关于在 GZIP 解压过程中设置 ProgressBar maxValue 和 publishProgress 值的主要内容,如果未能解决你的问题,请参考以下文章