Android - 閱讀巨大（30MB）文本文件並壓縮它們

Question

我想讀取兩個文件，加入它們的內容，然後GZIP它，以便我可以將它發送到服務器。

當文件是幾個MB，但其中一個重達〜30MB（生產預期大小）時，一切正常，但試圖讀取它時出現Out of memory on a 43628012-byte allocation錯誤。我不知道我做錯了什麼，因爲它在小文件上效果很好。

接下來是我用來讀取文本文件的代碼：

private String getTextFromFile(File fileName) { 
     StringBuilder logsHolder = new StringBuilder(); 
     BufferedReader input; 
     try { 
      input = new BufferedReader(new FileReader(fileName)); 
      String line = null; 
      String lineSeparator = System.getProperty("line.separator"); 
      while ((line = input.readLine()) != null){ 
       logsHolder.append(line); 
       logsHolder.append(lineSeparator); 
      } 
      input.close(); 
     } catch (IOException e) { 
      e.printStackTrace(); 
     } 
     return logsHolder.toString(); 
    } 

的錯誤讀線的幾千後的行logsHolder.append(line);啓動。接下來是logcat的輸出：

  01-04 09:54:25.852: D/dalvikvm(888): GC_FOR_ALLOC freed 1223K, 29% free 6002K/8364K, paused 21ms, total 21ms 
      01-04 09:54:25.892: D/dalvikvm(888): GC_FOR_ALLOC freed 1022K, 30% free 6235K/8860K, paused 16ms, total 17ms 
      01-04 09:54:25.932: D/dalvikvm(888): GC_FOR_ALLOC freed 884K, 27% free 6481K/8860K, paused 18ms, total 19ms 
      01-04 09:54:25.932: I/dalvikvm-heap(888): Grow heap (frag case) to 8.521MB for 1134874-byte allocation 
      01-04 09:54:25.952: D/dalvikvm(888): GC_FOR_ALLOC freed 738K, 32% free 6851K/9972K, paused 18ms, total 18ms 
      01-04 09:54:26.012: D/dalvikvm(888): GC_FOR_ALLOC freed 586K, 32% free 6851K/9972K, paused 18ms, total 18ms 
      01-04 09:54:26.012: I/dalvikvm-heap(888): Grow heap (frag case) to 9.422MB for 1702306-byte allocation 
      01-04 09:54:26.042: D/dalvikvm(888): GC_FOR_ALLOC freed 1108K, 37% free 7405K/11636K, paused 20ms, total 20ms 
      01-04 09:54:26.122: D/dalvikvm(888): GC_FOR_ALLOC freed 878K, 37% free 7405K/11636K, paused 21ms, total 21ms 
      01-04 09:54:26.122: I/dalvikvm-heap(888): Grow heap (frag case) to 10.776MB for 2553454-byte allocation 
      01-04 09:54:26.152: D/dalvikvm(888): GC_CONCURRENT freed 0K, 30% free 9899K/14132K, paused 10ms+2ms, total 27ms 
      01-04 09:54:26.152: D/dalvikvm(888): WAIT_FOR_CONCURRENT_GC blocked 17ms 
      01-04 09:54:26.242: D/dalvikvm(888): GC_FOR_ALLOC freed 2980K, 42% free 8236K/14132K, paused 16ms, total 16ms 
      01-04 09:54:26.252: I/dalvikvm-heap(888): Grow heap (frag case) to 12.805MB for 3830176-byte allocation 
      01-04 09:54:26.282: D/dalvikvm(888): GC_CONCURRENT freed 0K, 33% free 11977K/17876K, paused 10ms+3ms, total 27ms 
      01-04 09:54:26.282: D/dalvikvm(888): WAIT_FOR_CONCURRENT_GC blocked 8ms 
      01-04 09:54:26.432: D/dalvikvm(888): GC_FOR_ALLOC freed 4470K, 47% free 9483K/17876K, paused 17ms, total 17ms 
      01-04 09:54:26.442: I/dalvikvm-heap(888): Grow heap (frag case) to 15.849MB for 5745260-byte allocation 
      01-04 09:54:26.472: D/dalvikvm(888): GC_CONCURRENT freed 0K, 36% free 15094K/23488K, paused 17ms+2ms, total 33ms 
      01-04 09:54:26.472: D/dalvikvm(888): WAIT_FOR_CONCURRENT_GC blocked 15ms 
      01-04 09:54:26.663: D/dalvikvm(888): GC_FOR_ALLOC freed 6704K, 52% free 11353K/23488K, paused 20ms, total 20ms 
      01-04 09:54:26.683: I/dalvikvm-heap(888): Grow heap (frag case) to 20.415MB for 8617886-byte allocation 
      01-04 09:54:26.713: D/dalvikvm(888): GC_CONCURRENT freed 0K, 39% free 19769K/31904K, paused 17ms+2ms, total 32ms 
      01-04 09:54:26.713: D/dalvikvm(888): WAIT_FOR_CONCURRENT_GC blocked 14ms 
      01-04 09:54:27.033: D/dalvikvm(888): GC_FOR_ALLOC freed 10057K, 56% free 14158K/31904K, paused 31ms, total 31ms 
      01-04 09:54:27.053: I/dalvikvm-heap(888): Grow heap (frag case) to 27.264MB for 12926824-byte allocation 
      01-04 09:54:27.093: D/dalvikvm(888): GC_CONCURRENT freed 8415K, 59% free 18366K/44528K, paused 17ms+2ms, total 32ms 
      01-04 09:54:27.093: D/dalvikvm(888): WAIT_FOR_CONCURRENT_GC blocked 15ms 
      01-04 09:54:27.333: D/dalvikvm(888): GC_CONCURRENT freed 4324K, 59% free 18367K/44528K, paused 1ms+3ms, total 29ms 
      01-04 09:54:27.333: D/dalvikvm(888): WAIT_FOR_CONCURRENT_GC blocked 22ms 
      01-04 09:54:27.493: D/dalvikvm(888): GC_FOR_ALLOC freed 2345K, 59% free 18366K/44528K, paused 19ms, total 19ms 
      01-04 09:54:27.513: I/dalvikvm-heap(888): Grow heap (frag case) to 37.537MB for 19390232-byte allocation 
      01-04 09:54:27.563: D/dalvikvm(888): GC_CONCURRENT freed 0K, 42% free 37302K/63464K, paused 34ms+4ms, total 51ms 
      01-04 09:54:27.563: D/dalvikvm(888): WAIT_FOR_CONCURRENT_GC blocked 15ms 
      01-04 09:54:28.094: D/dalvikvm(888): GC_FOR_ALLOC freed 20815K, 62% free 24678K/63464K, paused 40ms, total 40ms 
      01-04 09:54:28.234: D/dalvikvm(888): GC_FOR_ALLOC freed 1814K, 62% free 24678K/63464K, paused 22ms, total 23ms 
      01-04 09:54:28.284: I/dalvikvm-heap(888): Grow heap (frag case) to 52.947MB for 29085344-byte allocation 
      01-04 09:54:28.344: D/dalvikvm(888): GC_FOR_ALLOC freed 18935K, 63% free 34146K/91868K, paused 21ms, total 21ms 
      01-04 09:54:29.245: D/dalvikvm(888): GC_FOR_ALLOC freed 8191K, 63% free 34146K/91868K, paused 50ms, total 51ms 
      01-04 09:54:29.846: D/dalvikvm(888): GC_FOR_ALLOC freed 6821K, 63% free 34138K/91868K, paused 33ms, total 33ms 
      01-04 09:54:29.846: I/dalvikvm-heap(888): Forcing collection of SoftReferences for 43628012-byte allocation 
      01-04 09:54:29.866: D/dalvikvm(888): GC_BEFORE_OOM freed 76K, 63% free 34061K/91868K, paused 27ms, total 27ms 
      01-04 09:54:29.866: E/dalvikvm-heap(888): Out of memory on a 43628012-byte allocation. 

我不知道，如果壓縮部分將在這樣一個大的緩衝工作，但暫時，我唯一的問題是與閱讀的巨大文本文件。

我希望你能幫我找到爲什麼這個失敗，我應該改變什麼才能使它工作。

編輯

下，如果我用這兩個文件的加入量壓縮代碼：

 File previousLog = SystemEventsReceiver.getPreviousLog(); 
     if (previousLog.exists()) { 
      logsHolder.append(getTextFromFile(previousLog)); 
     } 

     File currentLog = SystemEventsReceiver.getCurrentLog(); 
     if (currentLog.exists()) { 
      logsHolder.append(getTextFromFile(currentLog)); 
     } 

     Log.v("MyApp", "uncompressed logs: " + logsHolder.toString().getBytes().length); 
     // Compress logs. 
     byte[] compressedLogs = null; 
     try { 
      ByteArrayOutputStream os = new ByteArrayOutputStream(logsHolder.length()); 
      GZIPOutputStream gos = new GZIPOutputStream(os); 
      gos.write(logsHolder.toString().getBytes()); 
      gos.close(); 
      compressedLogs = os.toByteArray(); 
      os.close(); 
     } catch (IOException e) { 
      e.printStackTrace(); 
     } 
     Log.v("MyApp", "compressed logs: " + compressedLogs.length); 

Answer 1

感謝@ PhilW的意見，我想出了以下解決方案：

Log.v("MyApp", "reading logs"); 
    // Get logs. 
    File previousLog = SystemEventsReceiver.getPreviousLog(); 
    File currentLog = SystemEventsReceiver.getCurrentLog(); 

    int completeLogSize = (int) (currentLog.length() + previousLog.length()); 
    Log.v("MyApp", "uncompressed logs: " + completeLogSize); 
    // Compress logs. 
    byte[] compressedLogs = null; 
    try { 
     ByteArrayOutputStream os = new ByteArrayOutputStream(completeLogSize); 
     GZIPOutputStream gzipOS = new GZIPOutputStream(os); 

     if (previousLog.exists()) { 
      addLogToGZIP(previousLog, gzipOS); 
     } 
     if (currentLog.exists()) { 
      addLogToGZIP(currentLog, gzipOS); 
     } 

     gzipOS.close(); 
     compressedLogs = os.toByteArray(); 
     os.close(); 
    } catch (IOException e) { 
     e.printStackTrace(); 
    } 
    Log.v("MyApp", "compressed logs: " + compressedLogs.length); 



    private void addLogToGZIP(File logFile, GZIPOutputStream gzipOS) { 
     byte[] bytes = new byte[1024]; 

     try { 
      BufferedInputStream buffer = new BufferedInputStream(new FileInputStream(logFile)); 
      while (buffer.read(bytes, 0, bytes.length) != -1) { 
       gzipOS.write(bytes); 
      } 
      buffer.close(); 
     } catch (FileNotFoundException e) { 
      e.printStackTrace(); 
     } catch (IOException e) { 
      e.printStackTrace(); 
     } 
    } 

我從每個日誌文件中讀取字節並將其直接添加到GZIPOutputStream。 它對55MB文件（約1.100.000行）甚至100MB（〜2.200.000行）的文件效果很好。