//内部路径 Environment.getDataDirectory()=/data Environment.getDownloadCacheDirectory()=/cache Environment.getRootDirectory()=/system context.getCacheDir()=/data/data/com.penngo.test/cache context.getFilesDir()=/data/data/com.penngo.test/files  // 存储卡路径 Environment.getExternalStorageDirectory()=/storage/sdcard0  // 可选值DIRECTORY_MUSIC, DIRECTORY_PODCASTS, DIRECTORY_RINGTONES,  // DIRECTORY_ALARMS, DIRECTORY_NOTIFICATIONS, DIRECTORY_PICTURES,  // DIRECTORY_MOVIES, DIRECTORY_DOWNLOADS, or DIRECTORY_DCIM. 不能为null Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_MUSIC)=/storage/sdcard0/Music  // 与context.getFilesDir(相似，删除应用时会同时删除 context.getExternalFilesDir()=/storage/sdcard0/Android/data/com.penngo.test/files // 与context.getCacheDir()相似，删除应用时会同时删除 context.getExternalCacheDir()=/storage/sdcard0/Android/data/com.penngo.test/cache  System.getProperty("user.home")= System.getProperty("java.io.tmpdir")=/data/data/com.penngo.test/cache new File().getAbsolutePath()=/.   //判断存储卡是否存在 public static boolean isSdCardExist() {   if (Environment.getExternalStorageState().equals(     Environment.MEDIA_MOUNTED)) {
    //判断是否已经挂载    return true;   }   return false;  }