java 创建日志文件并保存应用程序日志

Posted 2021-05-08

class log {  
  
    private static final int READ_PERMISSION_CODE = 24;
    private static final int EXTERNAL_PERMISSION_CODE = 25;
  
        @Override
        protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        
        /*
        * Code for saving log files into external storage of Android device
        */

        if (ActivityCompat.checkSelfPermission(this, Manifest.permission.WRITE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {
            ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE}, EXTERNAL_PERMISSION_CODE);
        }
        if (ActivityCompat.checkSelfPermission(this, Manifest.permission.READ_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {
            ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.READ_EXTERNAL_STORAGE}, READ_PERMISSION_CODE);
        }

        if ( isExternalStorageWritable() ) {

            //File appDirectory = new File( Environment.getExternalStorageDirectory() + "/MyPersonalAppFolder" );
            File appDirectory = new File( Environment.getExternalStorageDirectory() + "/CollectionAutomationLog" );
            File logDirectory = new File( appDirectory + "/log" );
            File logFile = new File( logDirectory, "logcat" + System.currentTimeMillis() + ".txt" );

            // create app folder
            if ( !appDirectory.exists() ) {
                appDirectory.mkdir();
            }

            // create log folder
            if ( !logDirectory.exists() ) {
                logDirectory.mkdir();
            }

            // clear the previous logcat and then write the new one to the file
            try {
                Process process = Runtime.getRuntime().exec("logcat -c");
                process = Runtime.getRuntime().exec("logcat -f " + logFile);
            } catch ( IOException e ) {
                e.printStackTrace();
            }

        } else if ( isExternalStorageReadable() ) {
            // only readable
        } else {
            // not accessible
        }


        /*
        * Code completed for saving log files into external storage of Android device
        */

        setContentView(R.layout.activity_splash);
  .
  .
  .
}

/* Checks if external storage is available for read and write */
    public boolean isExternalStorageWritable() {
        String state = Environment.getExternalStorageState();
        if ( Environment.MEDIA_MOUNTED.equals( state ) ) {
            return true;
        }
        return false;
    }

    /* Checks if external storage is available to at least read */
    public boolean isExternalStorageReadable() {
        String state = Environment.getExternalStorageState();
        if ( Environment.MEDIA_MOUNTED.equals( state ) ||
                Environment.MEDIA_MOUNTED_READ_ONLY.equals( state ) ) {
            return true;
        }
        return false;
    }
    
}