java - Open a file from archive without temporary extraction

Question

Right now I'm working on an archive browsing application that lets users navigate through archive contents, extract the archives and preview the files inside the archive. I'm using java.util.zip API. To preview a file I'm extracting it temporarily and opening it as a usual existing file. As you may understand, that's not a good approach since it won't preview files if there's not enough space to make a temporary extraction. Is there a working solution for passing ZipInputStream to an Activity to open it as a file? Is there another workaround for this problem? Thanks in advance.

Answer 1

In principle, you could create a ContentProvider that serves up the ZipInputStream.

In this sample project I demonstrate how to create a ContentProvider supporting openFile() that uses a pipe created by ParcelFileDescriptor.createPipe() to serve up a file. createPipe() returns a pair (two-element array) of ParcelFileDescriptors representing the ends of the pipe. You use the second element out of the array to write to via an OutputStream; openFile() returns the first element out of the array to be passed by Android to the calling process. The caller would use openInputStream() to read in what you transfer via the pipe.

In my case, I am sending an asset on which I get an InputStream via AssetManager. In your case, you would use your ZipInputStream.

Note that my sample project assumes it is being run on a device that has a PDF viewer, since it is serving a PDF out of assets and trying to open it via startActivity().