【AndroidDevelopersTraining】101.显示快

<


RelativeLayout


xmlns:android


="http://schemas.android.com/apk/res/android"



android:layout_width


="match_parent"



android:layout_height


="match_parent"


>



...

<


QuickContactBadge



android:id


=@+id/quickbadge



android:layout_height


="wrap_content"



android:layout_width


="wrap_content"



android:scaleType


="centerCrop"


/>



...




RelativeLayout


>

//


The Cursor that contains contact rows


Cursor mCursor;

//


The index of the _ID column in the Cursor


int


mIdColumn;

//


The index of the LOOKUP_KEY column in the Cursor


int


mLookupKeyColumn;

//


A content URI for the desired contact


Uri mContactUri;

//


A handle to the QuickContactBadge view


QuickContactBadge mBadge;
...
mBadge

=

(QuickContactBadge) findViewById(R.id.quickbadge);

/*



* Insert code here to move to the desired cursor row



*/


//


Gets the _ID column index

mIdColumn =

mCursor.getColumnIndex(Contacts._ID);

//


Gets the LOOKUP_KEY index

mLookupKeyColumn =

mCursor.getColumnIndex(Contacts.LOOKUP_KEY);

//


Gets a content URI for the contact

mCOntactUri=


Contacts.getLookupUri(
mCursor.getLong(mIdColumn),
mCursor.getString(mLookupKeyColumn)
);
mBadge.assignContactUri(mContactUri);

//


The column in which to find the thumbnail ID


int


mThumbnailColumn;

/*



* The thumbnail URI, expressed as a String.
* Contacts Provider stores URIs as String values.



*/



String mThumbnailUri;
...

/*



* Gets the photo thumbnail column index if
* platform version >= Honeycomb



*/


if

(Build.VERSION.SDK_INT >=

Build.VERSION_CODES.HONEYCOMB) {
mThumbnailColumn

=


mCursor.getColumnIndex(Contacts.PHOTO_THUMBNAIL_URI);

//


Otherwise, sets the thumbnail column to the _ID column

}

else


{
mThumbnailColumn

=

mIdColumn;
}

/*



* Assuming the current Cursor position is the contact you want,
* gets the thumbnail ID



*/



mThumbnailUri

=

mCursor.getString(mThumbnailColumn);
...

/**



* Load a contact photo thumbnail and return it as a Bitmap,
* resizing the image to the provided image dimensions as needed.
*


@param


photoData photo ID Prior to Honeycomb, the contact's _ID value.
* For Honeycomb and later, the value of PHOTO_THUMBNAIL_URI.
*


@return


A thumbnail Bitmap, sized to the provided width and height.
* Returns null if the thumbnail is not found.



*/


private


Bitmap loadContactPhotoThumbnail(String photoData) {



//


Creates an asset file descriptor for the thumbnail file.

AssetFileDescriptor afd =

null


;



//


try-catch block for file not found


try


{



//


Creates a holder for the URI.


Uri thumbUri;



//


If Android 3.0 or later


if


(Build.VERSION.SDK_INT

>=


Build.VERSION_CODES.HONEYCOMB) {



//


Sets the URI from the incoming PHOTO_THUMBNAIL_URI

thumbUri =

Uri.parse(photoData);
}


else


{



//


Prior to Android 3.0, constructs a photo Uri using _ID


/*



* Creates a contact URI from the Contacts content URI
* incoming photoData (_ID)



*/


final

Uri cOntactUri=

Uri.withAppendedPath(
Contacts.CONTENT_URI, photoData);



/*



* Creates a photo URI by appending the content URI of
* Contacts.Photo.



*/



thumbUri

=


Uri.withAppendedPath(
contactUri, Photo.CONTENT_DIRECTORY);
}


/*



* Retrieves an AssetFileDescriptor object for the thumbnail
* URI
* using ContentResolver.openAssetFileDescriptor



*/



afd

=

getActivity().getContentResolver().
openAssetFileDescriptor(thumbUri,

"r"

);



/*



* Gets a file descriptor from the asset file descriptor.
* This object can be used across processes.



*/



FileDescriptor fileDescriptor

=

afd.getFileDescriptor();



//


Decode the photo file and return the result as a Bitmap



//


If the file descriptor is valid


if

(fileDescriptor !=

null


) {



//


Decodes the bitmap


return


BitmapFactory.decodeFileDescriptor(
fileDescriptor,


null

,

null


);
}



//


If the file isn't found

}

catch


(FileNotFoundException e) {



/*



* Handle file not found errors



*/



}



//


In all cases, close the asset file descriptor

}

finally


{



if

(afd !=

null


) {



try


{
afd.close();
}


catch


(IOException e) {}
}
}



return


null


;
}

...

/*



* Decodes the thumbnail file to a Bitmap.



*/



Bitmap mThumbnail

=


loadContactPhotoThumbnail(mThumbnailUri);

/*



* Sets the image in the QuickContactBadge
* QuickContactBadge inherits from ImageView, so



*/



mBadge.setImageBitmap(mThumbnail);

<


RelativeLayout


xmlns:android


="http://schemas.android.com/apk/res/android"



android:layout_width


="match_parent"



android:layout_height


="wrap_content"


>


<


QuickContactBadge



android:id


="@+id/quickcontact"



android:layout_height


="wrap_content"



android:layout_width


="wrap_content"



android:scaleType


="centerCrop"


/>


<


TextView


android:id


="@+id/displayname"



android:layout_width


="match_parent"



android:layout_height


="wrap_content"



android:layout_toRightOf


="@+id/quickcontact"



android:gravity


="center_vertical"



android:layout_alignParentRight


="true"



android:layout_alignParentTop


="true"


/>




RelativeLayout


>

/**



*
*



*/


private


class

ContactsAdapter

extends


CursorAdapter {



private


LayoutInflater mInflater;
...



public


ContactsAdapter(Context context) {



super

(context,

null

, 0

);



/*



* Gets an inflater that can instantiate
* the ListView layout from the file.



*/



mInflater

=

LayoutInflater.from(context);
...
}
...



/**



* Defines a class that hold resource IDs of each item layout
* row to prevent having to look them up each time data is
* bound to a row.



*/


private


class


ViewHolder {
TextView displayname;
QuickContactBadge quickcontact;
}
..
@Override



public


View newView(
Context context,
Cursor cursor,
ViewGroup viewGroup) {



/*


Inflates the item layout. Stores resource IDs in a
* in a ViewHolder class to prevent having to look
* them up each time bindView() is called.



*/


final

View itemView =


mInflater.inflate(
R.layout.contact_list_layout,
viewGroup,


false



);



final

ViewHolder holder =

new


ViewHolder();
holder.displayname

=


(TextView) view.findViewById(R.id.displayname);
holder.quickcontact

=


(QuickContactBadge)
view.findViewById(R.id.quickcontact);
view.setTag(holder);



return


view;
}
...
@Override



public


void


bindView(
View view,
Context context,
Cursor cursor) {



final

ViewHolder holder =

(ViewHolder) view.getTag();



final

String photoData =


cursor.getString(mPhotoDataIndex);



final

String displayName =


cursor.getString(mDisplayNameIndex);
...



//


Sets the display name in the layout

holder.displayname =

cursor.getString(mDisplayNameIndex);
...



/*



* Generates a contact URI for the QuickContactBadge.



*/


final

Uri cOntactUri=

Contacts.getLookupUri(
cursor.getLong(mIdIndex),
cursor.getString(mLookupKeyIndex));
holder.quickcontact.assignContactUri(contactUri);
String photoData

=

cursor.getString(mPhotoDataIndex);



/*



* Decodes the thumbnail file to a Bitmap.
* The method loadContactPhotoThumbnail() is defined
* in the section "Set the Contact URI and Thumbnail"



*/



Bitmap thumbnailBitmap

=


loadContactPhotoThumbnail(photoData);



/*



* Sets the image in the QuickContactBadge
* QuickContactBadge inherits from ImageView



*/



holder.quickcontact.setImageBitmap(thumbnailBitmap);
}

public


class

ContactsFragment

extends

Fragment

implements



LoaderManager.LoaderCallbacks



{
...

//


Defines a ListView


private


ListView mListView;

//


Defines a ContactsAdapter


private


ContactsAdapter mAdapter;
...

//


Defines a Cursor to contain the retrieved data


private


Cursor mCursor;

/*



* Defines a projection based on platform version. This ensures
* that you retrieve the correct columns.



*/


private


static


final

String[] PROJECTION =


{
Contacts._ID,
Contacts.LOOKUP_KEY,
(Build.VERSION.SDK_INT

>=


Build.VERSION_CODES.HONEYCOMB)

?


Contacts.DISPLAY_NAME_PRIMARY :
Contacts.DISPLAY_NAME
(Build.VERSION.SDK_INT

>=


Build.VERSION_CODES.HONEYCOMB)

?


Contacts.PHOTO_THUMBNAIL_ID :



/*



* Although it's not necessary to include the
* column twice, this keeps the number of
* columns the same regardless of version



*/



Contacts_ID
...
};

/*



* As a shortcut, defines constants for the
* column indexes in the Cursor. The index is
* 0-based and always matches the column order
* in the projection.



*/


//


Column index of the _ID column


private


int

mIdIndex = 0

;

//


Column index of the LOOKUP_KEY column


private


int

mLookupKeyIndex = 1

;

//


Column index of the display name column


private


int

mDisplayNameIndex = 3

;

/*



* Column index of the photo data column.
* It's PHOTO_THUMBNAIL_URI for Honeycomb and later,
* and _ID for previous versions.



*/


private


int

mPhotoDataIndex =


Build.VERSION.SDK_INT

>= Build.VERSION_CODES.HONEYCOMB ?
3

:


0

;
...

@Override

public


void


onCreate(Bundle savedInstanceState) {
...



/*



* Instantiates the subclass of
* CursorAdapter



*/



ContactsAdapter mContactsAdapter

=


new


ContactsAdapter(getActivity());



/*



* Gets a handle to the ListView in the file
* contact_list_layout.xml



*/



mListView

=

(ListView) findViewById(R.layout.contact_list_layout);
...
}
...

@Override

public


void


onActivityCreated(Bundle savedInstanceState) {
...



//


Sets up the adapter for the ListView


mListView.setAdapter(mAdapter);
...
}
...

public


void

onLoadFinished(Loader

loader, Cursor cursor) {



//


When the loader has completed, swap the cursor into the adapter.


mContactsAdapter.swapCursor(cursor);
}

@Override

public


void

onLoaderReset(Loader

loader) {



//


Removes remaining reference to the previous Cursor

mContactsAdapter.swapCursor(

null


);
}