1 Bitmap加載方式

在介紹Bitmap--OOM 異常時，首先介紹一下Bitmap有哪幾種加載方式。通常Bitmap的加載方式有Resource資源加載、本地（SDcard）加載、網絡加載等加載方式。

1.1 Resource資源加載

Assets資源加載方式：
[java]?view plaincopy

AssetManager?am?=?getAssets();??

InputStream?is?=?am.open("high_pixel_img.jpg");??

Bitmap?bitmap?=?BitmapFactory.decodeStream(is);??

?Res資源加載方式：
[java]?view plaincopy

Bitmap?bitmap?=?BitmapFactory.decodeResource(getResources(),?R.drawable.high_pixel_img);??

1.2 本地（SDcard）加載

[java]?view plaincopy

String?file_name?=?Environment.getExternalStorageDirectory().toString()+"/"+"high_pixel_img.jpg";??

nbsp;Bitmap?bitmap?=?BitmapFactory.decodeFile(file_name);??

文件描述符

1.3 網絡加載

注意：網絡加載圖片的時候必須在非主線成中操作

[java]?view plaincopy

String?website?=?"http://www.baidu.com/img/baidu_sylogo1.gif";??

URL?image_url?=?new?URL(website);??

HttpURLConnection?conn?=?(HttpURLConnection)?image_url.openConnection();??

conn.connect();??

InputStream?is?=?conn.getInputStream();??

bitmap?=?BitmapFactory.decodeStream(is);??

2 Bitmap | Drawable | InputStream | Byte[ ] 之間進行轉換

2.1 Drawable轉化成Bitmap

[java]?view plaincopy

Drawable?drawable?=?getResources().getDrawable(R.drawable.ic_launcher);??

Bitmap?bitmap?=?Bitmap.createBitmap(??

???????????????????????????????drawable.getIntrinsicWidth(),??

???????????????????????????????drawable.getIntrinsicHeight(),??

???????????????????????????????drawable.getOpacity()?!=?PixelFormat.OPAQUE???Bitmap.Config.ARGB_8888??

???????????????????????????????????????????????:?Bitmap.Config.RGB_565);??

Canvas?canvas?=?new?Canvas(bitmap);??

//canvas.setBitmap(bitmap);??

drawable.setBounds(0,?0,?drawable.getIntrinsicWidth(),?drawable.getIntrinsicHeight());??

drawable.draw(canvas);??

2. 2 Bitmap轉換成Drawable

?

[java]?view plaincopy

Drawable?drawable?=?new?BitmapDrawable(bitmap);??

?

2.3 Bitmap轉換成byte[]

[java]?view plaincopy

Bitmap?bitmap?=?BitmapFactory.decodeResource(getResources(),?R.drawable.high_pixel_img);??

ByteArrayOutputStream?baos?=?new?ByteArrayOutputStream();??

bitmap.compress(Bitmap.CompressFormat.PNG,?100,?baos);??

byte[]?info?=?baos.toByteArray();??

2.4 byte[]轉換成Bitmap

?

[java]?view plaincopy

Bitmap?bitmap?=?BitmapFactory.decodeByteArray(byte,?0,?b.length);??

2.5 InputStream轉換成Bitmap

[java]?view plaincopy

InputStream?is??=?getResources().openRawResource(id);??

Bitmap?bitmap?=?BitmaoFactory.decodeStream(is);??

2.6 InputStream轉換成byte[]

?

[java]?view plaincopy

InputStream?is?=?getResources().openRawResource(id);//也可以通過其他方式接收一個InputStream對象??

ByteArrayOutputStream?baos?=?new?ByteArrayOutputStream();????

byte[]?b?=?new?byte[1024*2];????

int?len?=?0;????

while?((len?=?is.read(b,?0,?b.length))?!=?-1)????

{????

???baos.write(b,?0,?len);????

???baos.flush();????

}????

byte[]?bytes?=?baos.toByteArray();????

3 轉換Bitmap大小

?

[java]?view plaincopy

Bitmap?bitmap?=?BitmapFactory.decodeResource(getResources(),?R.drawable.high_pixel_img);??

Bitmap?target?=?Bitmap.createBitmap(width,height,Bitmap.Config.ARGB_8888);??

Canvas?canvas?=?new?Canvas(tartget);??

canvas.scale(scale,scale);??

Paint?paint?=?new?Pain(Paint.FILTER_BITMAP_FLAG?|?Paint.DITHER_FLAG);??

canvas.drawBitmap(bitmap,0,0,paint);??

bitmap.recycle();??

?

?

4 將Bitmap保存為本地文件

?

[java]?view plaincopy

String?filename?=?"save.jpg";??

File?file?=?new?File(Environmnet.getExternalStorageDirectory,filename);??

try{??

????OutputStream?os??=??new?FileOutputString(file);??

????bitmap.compress(CompressFormat.JPEG,100,os);??

}catch(FileNotFoundException?e){??

???e.printStackTrace();??

}??

以上是關于Bitmap的相關操作，如果大家在閱讀中發現有什么問題，請在評論中留言。

轉載于:https://www.cnblogs.com/Free-Thinker/p/5544986.html

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