如何使用android在日誌文件中編寫異常？

Question

我想寫文本文件中的SD卡時，我得到一個 例外，從我的應用程序

如何實現我的 應用這個概念？

Answer 1

一般的方式去了解這一點，但在實踐中，你應該使用緩衝流時可能。

在你onCreate(Bundle savedInstanceState)回調或其他任何地方，你想這樣做記錄：

try 
{ 
//normal application code 

} 
//called whenever an Exception is thrown 
catch(Exception e) 
{ 
//stream for writing text 
FileWriter writer=null; 
try 
{ 
    writer = new FileWriter(this.getExternalFilesDir()); 
    //write to the SD card 
} catch(Throwable t) {} 
finally 
{ 
    if(writer != null) writer.close(); 
} 

} 

注意，我省略了檢查SD卡，但你應該總是這樣做。請參閱http://developer.android.com/guide/topics/data/data-storage.html#filesExternal

對不起，代碼格式糟糕。這個小文本框與Eclipse沒什麼兩樣。

Answer 2

我會創建我自己的記錄器類並使用它。其實這裏基本上是我做的，但你可以修改這個所以只寫了異常：

public class Logger { 
private static Logger instance = null; 
private static final int MAX_LOGS = 10; 

public enum Level { DEBUG, INFO, WARN, ERROR } 

private Level level = Level.ERROR; 
private String tag; 
private SimpleDateFormat format = new SimpleDateFormat("MM/dd/yy hh:mm:ss z"); 
private File log; 
private PrintWriter writer; 
private String supportEmail; 

public void LoggerSetup(String tag, String logFilename, Level level) { 
    //close previous 
    if(writer != null) { 
     writer.flush(); 
     writer.close(); 
     writer = null; 
    } 
    //open new 
    this.tag = tag; 
    this.log = createWriter(logFilename); 
    this.level = level; 
} 

public Logger(Context context) { 
    LoggerSetup(context.getPackageName(), "application.log", Level.INFO); 
} 

public static Logger getInstance(Context context) { 
    if(instance == null) { 
     instance = new Logger(context); 
    } 
    return instance; 
} 

public Logger() { 
    LoggerSetup("", "application.log", Level.INFO); 
} 

private File createWriter(String logFilename) { 
    try { 
     String state = Environment.getExternalStorageState(); 
     if(state.equals(Environment.MEDIA_MOUNTED)) { 
      File dir = new File(Environment.getExternalStorageDirectory(), "com.yourpackage"); 
      if(!dir.mkdirs()) { 
       Log.w(tag, "Could not create log directory: " + dir.getAbsolutePath()); 
      } 
      File log = new File(dir, logFilename); 
      if(log.exists()) { 
       rotate(log); 
      } 
      Log.i(tag, "Opening " + log.getAbsolutePath()); 
      writer = new PrintWriter(new FileWriter(log), true); 
      return log; 
     } else { 
      Log.w(tag, "Could not create log file because external storage state was " + state); 
     } 
    } catch(IOException ioe) { 
     Log.e(tag, "Failed while opening the log file.", ioe); 
    } 

    return null; 
} 

private void rotate(File log) { 
    int index = log.getName().lastIndexOf('.'); 
    if(index < 0) index = log.getName().length(); 
    String prefix = log.getName().substring(0, index); 
    String extension = log.getName().substring(index); 

    int lastLog = MAX_LOGS - 1; 
    File lastLogFile = new File(log.getParentFile(), prefix + "-" + lastLog + extension); 
    if(lastLogFile.exists()) lastLogFile.delete(); 

    for(int i = lastLog; i >= 1; --i) { 
     String filename = prefix + "-" + i + extension; 
     File l = new File(log.getParentFile(), filename); 
     if(l.exists()) { 
      File newLog = new File(log.getParentFile(), prefix + "-" + (i+1) + extension); 
      l.renameTo(newLog); 
     } 
    } 

    log.renameTo(new File(log.getParentFile(), prefix + "-1" + extension)); 
} 

public Level getLevel() { 
    return level; 
} 

public void setLevel(Level level) { 
    this.level = level; 
} 

public boolean isLoggable(Level level) { 
    return level.ordinal() >= this.level.ordinal(); 
} 

public void debug(String message, Object... parameters) { 
    if(parameters.length > 0) { 
     Log.d(tag, MessageFormat.format(message, parameters)); 
    } else { 
     Log.d(tag, message); 
    } 
    log(Level.DEBUG, message, parameters); 
} 

public void info(String message, Object... parameters) { 
    if(parameters.length > 0) { 
     Log.i(tag, MessageFormat.format(message, parameters)); 
    } else { 
     Log.i(tag, message); 
    } 
    log(Level.INFO, message, parameters); 
} 

public void warn(String message, Object... parameters) { 
    if(parameters.length > 0) { 
     Log.w(tag, MessageFormat.format(message, parameters)); 
    } else { 
     Log.w(tag, message); 
    } 
    log(Level.WARN, message, parameters); 
} 

public void error(String message, Object... parameters) { 
    if(parameters.length > 0) { 
     Log.e(tag, MessageFormat.format(message, parameters)); 
    } else { 
     Log.e(tag, message); 
    } 
    log(Level.ERROR, message, parameters); 
} 

public void error(Throwable throwable) { 
    String message = Log.getStackTraceString(throwable); 
    Log.e(tag, message, throwable); 
    log(Level.ERROR, message); 
} 

public void close() { 
    if(writer != null) { 
     writer.flush(); 
     writer.close(); 
     writer = null; 
    } 
} 

private void log(Level level, String message, Object... parameters) { 
    if(writer != null && isLoggable(level)) { 
     Date date = new Date(); 
     writer.print(format.format(date)); 
     writer.print(" "); 
     writer.print(level.toString()); 
     writer.print(" "); 
     writer.print(tag); 
     writer.print(" "); 
     writer.print(Thread.currentThread().getName()); 
     writer.print(" - "); 
     if(parameters.length > 0) { 
      writer.println(MessageFormat.format(message, parameters)); 
     } else { 
      writer.println(message); 
     } 
    } 
} 

protected void sendEmail(Context context) throws IOException { 
    File[] logs = log.getParentFile().listFiles(new FileFilter() { 
     @Override 
     public boolean accept(File pathname) { 
      return pathname.getName().endsWith(".log"); 
     } 
    }); 

    File temp = zipLogFiles(logs); 
    String[] mailto = { supportEmail }; 
    Intent sendIntent = new Intent(Intent.ACTION_SEND); 
    sendIntent.setType("application/zip"); 
    sendIntent.putExtra(Intent.EXTRA_EMAIL, mailto); 
    sendIntent.putExtra(Intent.EXTRA_SUBJECT, tag + ": Log File Attached"); 
    sendIntent.putExtra(Intent.EXTRA_TEXT, "A user has requested you look at some logs."); 
    sendIntent.putExtra(Intent.EXTRA_STREAM, Uri.fromFile(temp)); 
    sendIntent.setType("text/plain"); 
    context.startActivity(Intent.createChooser(sendIntent, "Send Logs To Support")); 
} 

private File zipLogFiles(File[] logs) throws IOException { 
    File zipfile = File.createTempFile("brewster", ".zip"); 
    ZipOutputStream stream = new ZipOutputStream(new FileOutputStream(zipfile)); 
    try { 
     for(File log : logs) { 
      ZipEntry entry = new ZipEntry(log.getName()); 
      stream.putNextEntry(entry); 
      copy(stream, log); 
      stream.closeEntry(); 
     } 
     stream.finish(); 
     return zipfile; 
    } finally { 
     stream.close(); 
    } 
} 

private void copy(OutputStream stream, File file) throws IOException { 
    InputStream istream = new FileInputStream(file); 
    try { 
     byte[] buffer = new byte[8096]; 
     int length = 0; 
     while((length = istream.read(buffer)) >= 0) { 
      stream.write(buffer, 0, length); 
     } 
    } finally { 
     istream.close(); 
    } 
} 

}