问如何从/proc/pid/stat获得应用程序的CPU总使用量？

EN

public void myWonderfulApp()
{
   // Some wonderfully written code here
   Integer lMyProcessID = android.os.Process.myPid();
   int lMyCPUUsage = getAppCPUUsage( lMyProcessID );
   // More magic
}


// Alternate way that I switched to.  I found the first version was slower
// this version only returns a single line for the app, so far less parsing
// and processing.
public static float getTotalCPUUsage2()
{
    try
    {
        // read global stats file for total CPU
        BufferedReader reader = new BufferedReader(new FileReader("/proc/stat"));
        String[] sa = reader.readLine().split("[ ]+", 9);
        long work = Long.parseLong(sa[1]) + Long.parseLong(sa[2]) + Long.parseLong(sa[3]);
        long total = work + Long.parseLong(sa[4]) + Long.parseLong(sa[5]) + Long.parseLong(sa[6]) + Long.parseLong(sa[7]);
        reader.close();

        // calculate and convert to percentage
        return restrictPercentage(work * 100 / (float) total);
    }
    catch (Exception ex)
    {
        Logger.e(Constants.TAG, "Unable to get Total CPU usage");
    }

    // if there was an issue, just return 0
    return 0;
}

// This is an alternate way, but it takes the entire output of 
// top, so there is a fair bit of parsing.
public static int getAppCPUUsage( Integer aAppPID)
{
    int lReturn = 0;
    // make sure a valid pid was passed
    if ( null == aAppPID && aAppPID > 0)
    {
        return lReturn;
    }

    try
    {
        // Make a call to top so we have all the processes CPU
        Process lTopProcess = Runtime.getRuntime().exec("top");
        BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(lTopProcess.getInputStream()));

        String lLine;

        // While we have stuff to read and we have not found our PID, process the lines
        while ( (lLine = bufferedReader.readLine()) != null )
        {
            // Split on 4, the CPU % is the 3rd field .
            // NOTE: We trim because sometimes we had the first field in the split be a "".
            String[] lSplit = lLine.trim().split("[ ]+", 4);

            // Don't even bother if we don't have at least the 4
            if ( lSplit.length > 3 )
            {
                // Make sure we can handle if we can't parse the int
                try
                {
                    // On the line that is our process, field 0 is a PID
                    Integer lCurrentPID = Integer.parseInt(lSplit[0]);

                    // Did we find our process?
                    if (aAppPID.equals(lCurrentPID))
                    {
                        // This is us, strip off the % and return it
                        String lCPU = lSplit[2].replace("%", "");

                        lReturn = Integer.parseInt(lCPU);
                        break;
                    }
                }
                catch( NumberFormatException e )
                {
                    // No op.  We expect this when it's not a PID line
                }
            }
        }

        bufferedReader.close();
        lTopProcess.destroy();      // Cleanup the process, otherwise you make a nice hand warmer out of your device

    }
    catch( IOException ex )
    {
        // Log bad stuff happened
    }
    catch (Exception ex)
    {
        // Log bad stuff happened
    }

    // if there was an issue, just return 0
    return lReturn;
}