在Android中多媒體文件(音樂/視頻/圖片)是通過MediaStore來統一管理的,本文所演示的例子是通過MediaStore獲取手機存儲中的圖片,然後在Gallery中顯示出來。例子最後的效果:
下面先貼出本文需要添加和修改的文件:main.xml
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
tools:context=".MainActivity" >
<Gallery android:id="@+id/gallery" android:layout_width="match_parent" android:layout_height="match_parent"/>
</LinearLayout>
上面的xml主要做的工作就是新建了一個Gallery,下面會用來存放圖片。
MainActivity.java
public class MainActivity extends Activity {
private Gallery mGallery;
private ArrayList<Bitmap> mImageArr = new ArrayList<Bitmap>();
public static final String LOG_TAG = "MainActivity";
private static final int LOAD_END = 1;
private static final String mUriImage = MediaStore.Images.Media.DATA;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mGallery = (Gallery)findViewById(R.id.gallery);
loadPicHandle.post(new LocadImage());//使用Handler在後臺線程獲取圖片,獲取完成之後發通知,UI線程更新顯示
}
private Handler loadPicHandle = new Handler(){
@Override
public void handleMessage(android.os.Message msg) {
switch(msg.what)
{
case LOAD_END:
mGallery.setAdapter(new ImageAdapter(MainActivity.this,mImageArr));
break;
default :
break;
}
};
};
public class LocadImage implements Runnable{
@Override
public void run() {
Context ctx = MainActivity.this;
ContentResolver contentR = ctx.getContentResolver();
Cursor cursor = null;
String[] projection = { MediaStore.Images.Media._ID,
MediaStore.Images.Media.MIME_TYPE,
MediaStore.Images.Media.DATA, MediaStore.Images.Media.SIZE };
String selection = MediaStore.Images.Media.MIME_TYPE + "=?";
String[] selectionArgs = { "image/jpeg" };
String sortOrder = MediaStore.Images.Media.DATE_MODIFIED + " desc";
try{
cursor = contentR.query(MediaStore.Images.Media.EXTERNAL_CONTENT_URI, projection, selection,
selectionArgs, sortOrder);
if( null == cursor)
{
Log.d(LOG_TAG,"cursor is null");
}
int iCount = cursor.getCount();
cursor.moveToFirst();//如果圖片過多內存不足會Crash,超過10張只加載10張
if( iCount > 10 )
{
iCount = 10;
}
for( int i = 0; i < iCount; i++ )
{
int index = cursor.getColumnIndex(mUriImage);
String src = cursor.getString(index);
Log.d(LOG_TAG,"src:"+src);
//通過圖片的路徑加載圖片
Bitmap bitmap = BitmapFactory.decodeFile( src, null );
mImageArr.add(bitmap);
cursor.moveToNext();
}
if( !mImageArr.isEmpty() )
{
Message msg = Message.obtain();
msg.what = LOAD_END;
loadPicHandle.sendMessage(msg);
}
}catch(Exception e){
Log.e(LOG_TAG, e.getMessage());
}
finally{
cursor.close();
}
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
private class ImageAdapter extends BaseAdapter{
private Context mContext;
ArrayList<Bitmap> mImageArr;
public ImageAdapter(Context mContext,ArrayList<Bitmap> mImageArr) {
this.mContext = mContext;
this.mImageArr = mImageArr;
}
@Override
public int getCount() {
// TODO Auto-generated method stub
return mImageArr.size();
}
@Override
public Object getItem(int arg0) {
// TODO Auto-generated method stub
return mImageArr.get(arg0);
}
@Override
public long getItemId(int arg0) {
// TODO Auto-generated method stub
return arg0;
}
@Override
public View getView(int position, View arg1, ViewGroup arg2) {
Tools.log("getView position:"+position);
ImageView image = new ImageView(mContext);
image.setImageBitmap(mImageArr.get(position));
image.setLayoutParams(new Gallery.LayoutParams(640, 640));
return image;
}
}
}