Using content providers in Android

In this blog post I'll show you how to get data stored on an Android phone using content providers. We'll write an app that fetches all the bookmarks and history from the phone's browser.

Most Data in Android is exposed through so called "Content Providers". The person who wrote a specific part of Android (i.e. the browser, but surely it wasn't just one person), could decide how to implement the storage. If he used SQLite or just a basic file or json, etc. It didn't matter because Google decided to let their developers implement these content providers so that there would be a standard way for developers like us, to access the data.

In Android all the content providers are stored in the package: android.provider.*

They are queried using their URIs and Cursors.

Specifically the Browser's Bookmark and History content provider URI is in: android.provider.Browser.BOOKMARKS_URI
(The name is a bit misleading, since it is the URI for BOTH Bookmarks and History.)

To retrieve data you need to find the names of the columns you want to retrieve and put them in an Array. You can find the package that contains the column definition for the bookmarks and history here.

So let's get started!

Let's first set up all the variables:

import android.widget.Button;
import android.provider.Browser;
import android.net.Uri;

import java.util.List;

Button getBookmarksButton = (Button)this.findViewById(R.id.getBookmarksButton);
// I have set up a simple button in my layout, for which we will write a onClick listener.

Uri bookmarks =  Browser.BOOKMARKS_URI;
// The URI to query for bookmarks and history

List bookmarksList = new ArrayList();
// Here we'll store the retrieved data.

String[] columns = new String[] {
    BookmarkColumns.URL
};
// Array of all the columns you want to get. If you wanted any more like when it was created,
// just add another entry in the Array.

Now that we have the basic variables we can write the cursor. The function that creates it takes a lot of arguments. As you can see not many of these are important for us:

import android.database.Cursor;

Cursor managedCursor = managedQuery(
    bookmarks, // URI of the resource
    columns,   // Which columns to return
    null,      // Which rows to return (all rows)
    null,      // Selection arguments (none)
    null);     // Order the results (in the order they come)

Next we'll make a new onClick listener for the button. This listener basically loops through all the data rows and does something with them:

import android.view.View.OnClickListener;

getBookmarksButton.setOnClickListener(new OnClickListener() {
    @Override
    public void onClick(View v) {
        if (managedCursor.moveToFirst()) {
            String url;
            // Variable for holding the retrieved URL
            int urlColumn = cur.getColumnIndex(BookmarkColumns.URL);
            // Reference to the the column containing the URL

            do {
                url = cur.getString(urlColumn);
                // Get the field values
                bookmarksList.add(url);
                // Do something with the values.
            } while (managedCursor.moveToNext());

        }
    }
});

Now you have a list containing the bookmarks and history of a phones browser and you could for example send the urls to a server.

You can download the whole Activity here