Android local file path cache method to get a summary of each

introduction
Several methods of obtaining path

Look at the test code and print the log
Print log
analysis

Several common conversion method

File 转 Uri
Uri 转 File
Turn Bitmap file path
Bitmap file transfer

introduction

Daily development always encounter need to cache files locally, has always been a little confused on several ways to get the path of the corresponding cache path, the path of several methods available summary of what the corresponding

Several methods of obtaining path

Look at the test code and print the log

String CacheFilePath =getCacheDir().getAbsolutePath();
String ExternalCacheFilePath = getExternalCacheDir().getAbsolutePath();
String ExternalStorageFilePath =Environment.getExternalStorageDirectory().getAbsolutePath();

File CacheFile = new File(CacheFilePath,"CacheDir.txt");
File ExternalCacheFile = new File(ExternalCacheFilePath,"ExternalCacheDir.txt");
File ExternalStorageFile = new File(ExternalStorageFilePath,"ExternalStorage.txt");


  try {

        if (CacheFile.createNewFile()){
           Log.e("FileTest","CacheFile is created ：" + CacheFile.getAbsolutePath());
        }else if (CacheFile.exists()){
           Log.e("FileTest","CacheFile is created ：" + CacheFile.getAbsolutePath());
        }

        if (ExternalCacheFile.createNewFile()){
          Log.e("FileTest","ExternalCacheFile is created " + ExternalCacheFile.getAbsolutePath())
        }else if (ExternalCacheFile.exists()){
          Log.e("FileTest","ExternalCacheFile is created " + ExternalCacheFile.getAbsolutePath());
        }

        if (ExternalStorageFile.createNewFile()){ //NEED PERMISSION
          Log.e("FileTest","ExternalStorageFile is created :" + ExternalStorageFile.getAbsolutePath());
        }else if (ExternalStorageFile.exists()){
          Log.e("FileTest","ExternalStorageFile is created :" + ExternalStorageFile.getAbsolutePath());
        }
  } catch (IOException e) {
         e.printStackTrace();
  }

Print log

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analysis

Corresponding to the three methods:

        getCacheDir()
        getExternalCacheDir()
        Environment.getExternalStorageDirectory()

Belong to the internal memory: a first method
Belonging to the external storage: After two methods

The difference between the three directories

method	category	Competence	path	Remark
context.getCacheDir()	Internal memory	You do not need permission	data / data / package name / cache	Automatically deleted after uninstalling applications
context.getExternalCacheDir ()	External storage	You do not need permission	Android / data / package name / cache	Automatically deleted after uninstalling applications
getExternalFilesDir(String type)	External storage	You do not need permission	Android/data/包名/files	If the incoming non-empty String will create the appropriate folder, such as incoming "test" is the Android / data / package name / files / test in its directory; automatically deleted after uninstalling applications
Environment.getExternalStorageDirectory ()	External storage	Need permission	SD card or an external storage root path	After uninstalling the application still exists

And in the path of internal storage data / data we have on file manager on the phone can not see, in the lower right corner to pull over on the AS file management can be seen here
Here Insert Picture Description

Several common conversion method

File 转 Uri

private static Uri getUriForFile(Context context, File file) {
        if (context == null || file == null) {//简单地拦截一下
            throw new NullPointerException();
        }
        Uri uri;
        if (Build.VERSION.SDK_INT >= 24) {
            uri = FileProvider.getUriForFile(context, "com.hjl.android7.fileprovider", file);
        } else {
            uri = Uri.fromFile(file);
        }
        return uri;
}

Uri 转 File

public File uri2File(Uri uri) { return new File(uri.getPath()); }

Turn Bitmap file path

public Bitmap File2Bitmap(String filePath){
    File file = new File(filePath);
    Uri uri = Uri.fromFile(file);
    Bitmap bitmap = MediaStore.Images.Media.getBitmap(mContext.getContentResolver(), uri);
}

Bitmap file transfer

public static boolean writeBitmapToFile(Bitmap bitmap, File file, int quality){
    	boolean flag = false;
		try {
			FileOutputStream fos = new FileOutputStream(file);
			flag = bitmap.compress(Bitmap.CompressFormat.JPEG, quality, fos);  
			fos.flush();
			fos.close();
		} catch (Exception e) {
			e.printStackTrace();
		}
		return flag;
    }