how to read from a zipfile in a folder which was selected by the ACTION_OPEN_DOCUMENT_TREE Intent?

问题

how to read from a zipfile in a folder which was selected by the ACTION_OPEN_DOCUMENT_TREE Intent ?

My app let the user choose a folder through the ACTION_OPEN_DOCUMENT_TREE Intent. In that folder i will have a Zipfile with a specific name. Goal is to read that Zipfile with java.util.zip.ZipFile.

How do I instantiate a ZipFile with this specific Zipfilename from the provided URI (Folderinfo) in onActivityResult ?

protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    Uri treeUri = data.getData();
    String sPath=treeUri.getPath();

    java.util.zip.ZipFile myzip=new java.util.zip.ZipFile("mypath"); <-- Constructor expects File or Path as String. Howto handle this with the Uri ?

回答1:

How do I instantiate a ZipFile with this specific Zipfilename from the provided URI (Folderinfo) in onActivityResult ?

You can't, as there is no file, and ZipFile needs a file. You can only get an InputStream, using openInputStream() on a ContentResolver, and that only if you get a Uri to that specific file that you are looking for.

Your options appear to be:

• Use ZipInputStream, which can wrap an InputStream

• Find some third-party library that accepts an InputStream as input and gives you a better API

• Copy the ZIP flie to your app's portion of internal storage and read its contents using ZipFile

回答2:

I was working on this problem and ended up going with a strategy @CommonsWare mentioned as the third option, which is copying a file to non-sdcard place and load as a ZipFile. It works well so I share my snippet for everybody.

 public static ZipFile loadCachedZipFromUri(Context context, Uri uri, String filename){
    File file = new File(context.getCacheDir(), filename);
    String fileName = context.getCacheDir().getAbsolutePath() + '/' + filename;
    ZipFile zip = null;

    if (file.exists()){
        Log.d(TAG, "file exists");
        try {
            if(Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) { // N for Nougat
                zip = new ZipFile(fileName, Charset.forName("ISO-8859-1"));

            }else{
                zip = new ZipFile(fileName);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
        return zip;
    }

    DocumentFile dest = DocumentFile.fromFile(file);

    InputStream in = null;
    OutputStream out = null;

    Log.d(TAG, "Copy started");
    try {
        in = context.getContentResolver().openInputStream(uri);
        out = context.getContentResolver().openOutputStream(dest.getUri());
        byte[] buf = new byte[2048];
        int len = 0;
        while((len = in.read(buf)) >= 0){
            out.write(buf, 0, len);
        }

    } catch (FileNotFoundException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }finally {
        try {
            in.close();
            out.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    Log.d(TAG, "Load copied file");
    try {
        if(Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) { // N for Nougat
            zip = new ZipFile(fileName, Charset.forName("ISO-8859-1"));

        }else{
            zip = new ZipFile(fileName);
        }
    } catch (IOException e) {
        e.printStackTrace();
    }
    return zip;
}

来源：https://stackoverflow.com/questions/29746924/how-to-read-from-a-zipfile-in-a-folder-which-was-selected-by-the-action-open-doc