CachedFileContentProvider.java

package com.realtrackandroid.providers;

import java.io.File;
import java.io.FileNotFoundException;

import android.content.ContentProvider;
import android.content.ContentValues;
import android.content.UriMatcher;
import android.database.Cursor;
import android.net.Uri;
import android.os.ParcelFileDescriptor;

// Source: http://stephendnicholas.com/archives/974
public class CachedFileContentProvider extends ContentProvider {

  // The authority is the symbolic name for the provider class
  public static final String AUTHORITY = CachedFileContentProvider.class.getCanonicalName();

  // UriMatcher used to match against incoming requests
  private UriMatcher uriMatcher;

  @Override
  public boolean onCreate() {
    uriMatcher = new UriMatcher(UriMatcher.NO_MATCH);

    // Add a URI to the matcher which will match against the form
    // 'content://com.stephendnicholas.gmailattach.provider/*'
    // and return 1 in the case that the incoming Uri matches this pattern
    uriMatcher.addURI(AUTHORITY, "*", 1);

    return true;
  }

  @Override
  public ParcelFileDescriptor openFile(Uri uri, String mode) throws FileNotFoundException {

    // Check incoming Uri against the matcher
    switch (uriMatcher.match(uri)) {

    // If it returns 1 - then it matches the Uri defined in onCreate
      case 1:

        // The desired file name is specified by the last segment of the
        // path
        // E.g.
        // 'content://com.hackforchange.providers/Data_Report.csv'
        // Take this and build the path to the file
        String fileLocation = getContext().getCacheDir() + File.separator
                + uri.getLastPathSegment();

        // Create & return a ParcelFileDescriptor pointing to the file
        // Note: I don't care what mode they ask for - they're only getting
        // read only
        ParcelFileDescriptor pfd = ParcelFileDescriptor.open(new File(fileLocation),
                ParcelFileDescriptor.MODE_READ_ONLY);
        return pfd;

        // Otherwise unrecognised Uri
      default:
        throw new FileNotFoundException("Unsupported uri: " + uri.toString());
    }
  }

  // Not supported / used / required for this example
  @Override
  public int update(Uri uri, ContentValues contentvalues, String s, String[] as) {
    return 0;
  }

  @Override
  public int delete(Uri uri, String s, String[] as) {
    return 0;
  }

  @Override
  public Uri insert(Uri uri, ContentValues contentvalues) {
    return null;
  }

  @Override
  public String getType(Uri uri) {
    return null;
  }

  @Override
  public Cursor query(Uri uri, String[] projection, String s, String[] as1, String s1) {
    return null;
  }
}