多个表的内容提供者

Question

I am new in Android and am implementing a content provider for 5 tables. My Questions Are: Should I have a Content Provider for each table or multiple tables in a single Content provider? Since the Content Provider has a single insert, update, query, delete methods.

How can I include only one Content Provider in my application? I have searched and in Most of the examples, I only find a single table apps.

Where do I have to use switch conditions to support multiple tables with the same Content Provider?

please give me some idea.

Answer 1

You can use the URI parameter:

List<String> android.net.Uri.getPathSegments()

If your URI is, for example:

content://com.mypackage.MyContentProvider/MyTable

MyTable will be in the list returned by getPathSegments(); .

Then you have to specify your table in the URI and in insert, update, query, delete methods in provider build a query depending on the URI parameter.

To avoid testing on URI you can add to you provider an Abstract method called getTableName() witch will return your tableName as String .

Then extend your provider to 5 classes Table1Provider , Table2Provider etc. and implement method

Class abstract  MyProvider extends ContentProvider{

public abstract String getTableName();

 @Override
  public Cursor query(Uri uri, String[] projection, String selection,
      String[] selectionArgs, String sortOrder) {

   ///...
    // Set the table
    queryBuilder.setTables(getTableName());

    //...
    return cursor;
  }
}

class Table1Provider extend MyProvider{

public String getTableName(){
   return "Table1";
}

Then instantiate the Table1Provider instead of the abstract provider.

Answer 2

Make one provider. Use the URIMatcher class provided by Android to match content URIs with different tables.

Read here: http://developer.android.com/guide/topics/providers/content-provider-creating.html#ContentURI