Android 异步下载 _android

【Android 异步下载】宁可枝头抱香死，何曾吹落北风中。这篇文章主要讲述Android 异步下载相关的知识，希望能为你提供帮助。

package com.example.demo1; import java.io.File; import java.io.FileOutputStream; import java.io.IOException; import java.io.InputStream; import java.net.HttpURLConnection; import java.net.URL; import com.tiffdecoder.TiffDecoder; import android.app.Activity; import android.graphics.Bitmap; import android.os.AsyncTask; import android.widget.ImageView; public class DownloadImagesTask extends AsyncTask< Object, Void, Bitmap> { ImageView imageView = null; Activity activity = null; @Override protected Bitmap doInBackground(Object... parameters) { this.imageView = (ImageView)parameters[0]; this.activity = (Activity)parameters[1]; try { return download_Image((String)imageView.getTag()); } catch (IOException e) { e.printStackTrace(); } return null; }@Override protected void onPostExecute(Bitmap result) { if(result != null) imageView.setImageBitmap(result); }private Bitmap download_Image(String url) throws IOException { File file = downloadFile(url); TiffDecoder.nativeTiffOpen(file.getPath()); int[] pixels = TiffDecoder.nativeTiffGetBytes(); Bitmap mBitmap = Bitmap.createBitmap(pixels, TiffDecoder.nativeTiffGetWidth(), TiffDecoder.nativeTiffGetHeight(),Bitmap.Config.ARGB_8888); TiffDecoder.nativeTiffClose(); return mBitmap; }private File downloadFile(String strUrl) throws IOException { URL url = new URL(strUrl); HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection(); urlConnection.setRequestMethod("GET"); urlConnection.setDoOutput(true); urlConnection.connect(); File file = File.createTempFile("myfile", ".tif", this.activity.getCacheDir()); if(file.exists()) file.delete(); file.createNewFile(); FileOutputStream fileOutput = new FileOutputStream(file); InputStream inputStream = urlConnection.getInputStream(); byte[] buffer = new byte[1024]; int bufferLength = 0; while ( (bufferLength = inputStream.read(buffer)) > 0 ) { fileOutput.write(buffer, 0, bufferLength); } fileOutput.close(); return file; } }

public class MainActivity extends Activity {@Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); StrictMode.setThreadPolicy(new StrictMode.ThreadPolicy.Builder().detectDiskReads().detectDiskWrites().detectNetwork().penaltyLog().build()); StrictMode.setVmPolicy( new StrictMode.VmPolicy.Builder().detectLeakedSqlLiteObjects().detectLeakedClosableObjects().penaltyLog().penaltyDeath().build()); getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN); ImageView image = (ImageView)this.findViewById(R.id.image); image.setTag("http://xibei1-image.xxx.com/00006009b4673bbc-ff2a-49bd-91fe-764c01b2acce01.tif"); new DownloadImagesTask().execute(image,this); } }