Android development: Using Handler encapsulation to download image tools (source code sharing)

If you download an image, you have to rewrite the Http protocol once. It is too troublesome to start multiple threads and transfer the handler information. We can encapsulate a tool class directly, so that we can call it at any time during future development.

(1) Add permissions to the list file

(2) editing tool

Package com. example. g05_handler; import java. io. IOException; import org. apache. http. httpResponse; import org. apache. http. client. clientProtocolException; import org. apache. http. client. httpClient; import org. apache. http. client. methods. httpGet; import org. apache. http. impl. client. defaultHttpClient; import org. apache. http. util. entityUtils; import android. annotation. suppressLint; import android. app. progressDialog; Import android. content. context; import android. OS. handler; import android. OS. message; import android. util. log; public class DownLoad {private ProgressDialog dialog; public DownLoad (Context context) {// TODO Auto-generated constructor stubdialog = new ProgressDialog (context); dialog. setTitle ("prompt"); dialog. setMessage ("loading") ;}@ SuppressLint ("HandlerLeak") public void Down (final String path, final DownLoadC Allback callback) {final Handler handler = new Handler () {@ Overridepublic void handleMessage (Message msg) {// TODO Auto-generated method stubsuper. handleMessage (msg); byte [] result = (byte []) msg. obj; callback. download (result); if (msg. what = 1) {dialog. dismiss () ;}}; class MyThread implements Runnable {@ Overridepublic void run () {// TODO Auto-generated method stubHttpClient client = new DefaultHttpC Lient (); HttpGet httpGet = new HttpGet (path); try {HttpResponse httpResponse = client.exe cute (httpGet); Log. I ("TAG", "------>" + httpResponse. getStatusLine (). getStatusCode (); if (httpResponse. getStatusLine (). getStatusCode () = 200) {byte [] result = EntityUtils. toByteArray (httpResponse. getEntity (); Message message = Message. obtain (); message. obj = result; message. what = 1; handler. sendMessage (message );}} Catch (ClientProtocolException e) {// TODO Auto-generated catch blocke. printStackTrace ();} catch (IOException e) {// TODO Auto-generated catch blocke. printStackTrace ();} finally {if (client! = Null) {client. getConnectionManager (). shutdown () ;}};} new Thread (new MyThread ()). start (); dialog. show ();} public interface DownLoadCallback {public void download (byte [] data );}}

(3) call this tool class

package com.example.g05_handler;import com.example.g05_handler.DownLoad.DownLoadCallback;import android.os.Bundle;import android.app.Activity;import android.graphics.Bitmap;import android.graphics.BitmapFactory;import android.view.Menu;import android.view.View;import android.widget.Button;import android.widget.ImageView;public class MainActivity extends Activity {    private Button button;    private ImageView imageView;    private final String path="http://avatar.csdn.net/D/7/5/1_u013900875.jpg";@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);button=(Button)this.findViewById(R.id.button1);imageView=(ImageView)this.findViewById(R.id.imageView1);button.setOnClickListener(new View.OnClickListener() {@Overridepublic void onClick(View v) {// TODO Auto-generated method stubDownLoad downLoad=new DownLoad(MainActivity.this);downLoad.Down(path, new DownLoadCallback() {@Overridepublic void download(byte[] data) {// TODO Auto-generated method stubBitmap bitmap=BitmapFactory.decodeByteArray(data, 0, data.length);imageView.setImageBitmap(bitmap);}});}});}@Overridepublic 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;}}