public classUtilsBitmap{
/**
 * 讀取一個縮放後的圖片，限定圖片大小，避免OOM
 * @paramuri圖片uri，支援“file://”、“content://”
 * @parammaxWidth最大允許寬度
 * @parammaxHeight最大允許高度
 * @return返回一個縮放後的Bitmap，失敗則返回null
 */
public staticBitmapdecodeUri(Context context,Uri uri,intmaxWidth,intmaxHeight){
    BitmapFactory.Options options=newBitmapFactory.Options();
    options.inJustDecodeBounds=true; //只讀取圖片尺寸
    resolveUri(context,uri,options);

	//計算實際縮放比例
    intscale=1;
    for(inti=0;i<Integer.MAX_VALUE;i++){
		if((options.outWidth/scale>maxWidth&&options.outWidth/scale>maxWidth*1.4)||
			(options.outHeight/scale>maxHeight&&options.outHeight/scale>maxHeight*1.4)){
				scale++;
		}else{
			break;
		}
    }

    options.inSampleSize=scale;
    options.inJustDecodeBounds=false;//讀取圖片內容
    options.inPreferredConfig=Bitmap.Config.RGB_565;//根據情況進行修改
    Bitmap bitmap=null;
    try{
        bitmap=resolveUriForBitmap(context,uri,options);
    }catch(Throwable e){
        e.printStackTrace();
    }
    returnbitmap;
}


private static voidresolveUri(Context context,Uri uri,BitmapFactory.Options options){
    if(uri==null){
        return;
    }
    String scheme=uri.getScheme();
    if(ContentResolver.SCHEME_CONTENT.equals(scheme)||
        ContentResolver.SCHEME_FILE.equals(scheme)){
			InputStream stream=null;
        try{
			stream=context.getContentResolver().openInputStream(uri);
			BitmapFactory.decodeStream(stream,null,options);
        }catch(Exception e){
			Log.w("resolveUri","Unable to open content: "+uri,e);
        }finally{
			if(stream!=null){
				try{
					stream.close();
				}catch(IOException e){
					Log.w("resolveUri","Unable to close content: "+uri,e);
				}
			}
        }
    }else if(ContentResolver.SCHEME_ANDROID_RESOURCE.equals(scheme)){
        Log.w("resolveUri","Unable to close content: "+uri);
    }else{
        Log.w("resolveUri","Unable to close content: "+uri);
    }
}

private staticBitmapresolveUriForBitmap(Context context,Uri uri,BitmapFactory.Options options){
    if(uri==null){
        return null;
    }

    Bitmap bitmap=null;
    String scheme=uri.getScheme();
    if(ContentResolver.SCHEME_CONTENT.equals(scheme)||
        ContentResolver.SCHEME_FILE.equals(scheme)){
        InputStream stream=null;
        try{
			stream=context.getContentResolver().openInputStream(uri);
			bitmap=BitmapFactory.decodeStream(stream,null,options);
        }catch(Exception e){
			Log.w("resolveUriForBitmap","Unable to open content: "+uri,e);
        }finally{
			if(stream!=null){
				try{
					stream.close();
				}catch(IOException e){
					Log.w("resolveUriForBitmap","Unable to close content: "+uri,e);
				}
			}
		}
	}else if(ContentResolver.SCHEME_ANDROID_RESOURCE.equals(scheme)){
        Log.w("resolveUriForBitmap","Unable to close content: "+uri);
    }else{
        Log.w("resolveUriForBitmap","Unable to close content: "+uri);
    }

    returnbitmap;
}
}