需求：從服務(wù)器下載一張圖片，顯示在ImageView控件上，并將該圖片保存在移動設(shè)備的SD上。
步驟：
（一）獲得輸入流
//urlPath:服務(wù)器路徑;
public InputStream getUrlInputStream(String urlPath) throws IOException{
URL url=new URL(urlPath);
HttpURLConnection conn=(HttpURLConnection) url.openConnection();
InputStream in=conn.getInputStream();
if(in!=null){
return in;
}else{
Log.i("test", "輸入流對象為空");
return null;
}
}
（二）將輸入流轉(zhuǎn)化為Bitmap流
public Bitmap getMyBitmap(InputStream in){
Bitmap bitmap=null;
if(in!=null){
bitmap=BitmapFactory.decodeStream(in);
//BitmapFactory的作用：create Bitmap objects from various sources,including files,streams and byte-arrays;
return bitmap;
}else{
Log.i("test", "輸入流對象in為空");
return null;
}
}
（三）給ImageView對象賦值
public void setWidgetImage(Bitmap bitmap){
ImageView img=new ImageView(this);
if(bitmap!=null){
img.setImageBitmap(bitmap);
}
}
（四）獲取SD卡上的文件存儲路徑
public void createSDFile(){
File sdroot=Environment.getExternalStorageDirectory();
File file=new File(sdroot+"/Android/date/包名/文件名");
if(Environment.MEDIA_MOUNTED.equals(Environment.getExternalStorageState())){
/**
* 相關(guān)操作
*/
}
}
注意:SD卡的權(quán)限（五）將圖片保存到SD卡上
public boolean readToSDCard(File file,Bitmap bitmap) throws FileNotFoundException{
FileOutputStream os=new FileOutputStream(file);
return bitmap.compress(Bitmap.CompressFormat.PNG, 90, os);
//bitmap.compress()的作用:write a compressed version of the bitmap to the specified outputstream;
//true:表示操作成功，false:表示操作失敗
}