Android文件下载进度条的实现

main.xml：

 

main.java:

package com.pocketdigi.download; import java.io.FileOutputStream; import java.io.IOException; import java.io.InputStream; import java.net.URL; import java.net.URLConnection; import org.apache.http.client.ClientProtocolException; import android.app.Activity; import android.os.Bundle; import android.os.Handler; import android.os.Message; import android.util.Log; import android.widget.ProgressBar; import android.widget.TextView; import android.widget.Toast; public class main extends Activity { /** Called when the activity is first created. */ ProgressBar pb; TextView tv; int fileSize; int downLoadFileSize; String fileEx,fileNa,filename; private Handler handler = new Handler() { @Override public void handleMessage(Message msg) {//定义一个Handler，用于处理下载线程与UI间通讯 if (!Thread.currentThread().isInterrupted()) { switch (msg.what) { case 0: pb.setMax(fileSize); case 1: pb.setProgress(downLoadFileSize); int result = downLoadFileSize * 100 / fileSize; tv.setText(result + "%"); break; case 2: Toast.makeText(main.this, "文件下载完成", 1).show(); break; case -1: String error = msg.getData().getString("error"); Toast.makeText(main.this, error, 1).show(); break; } } super.handleMessage(msg); } }; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); pb=(ProgressBar)findViewById(R.id.down_pb); tv=(TextView)findViewById(R.id.tv); new Thread(){ public void run(){ try { down_file("http://wallpaper.pocketdigi.com/upload/1/bigImage/1284565196.jpg","/sdcard/"); //下载文件，参数：第一个URL，第二个存放路径 } catch (ClientProtocolException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } }.start(); } public void down_file(String url,String path) throws IOException{ //下载函数 filename=url.substring(url.lastIndexOf("/") + 1); //获取文件名 URL myURL = new URL(url); URLConnection conn = myURL.openConnection(); conn.connect(); InputStream is = conn.getInputStream(); this.fileSize = conn.getContentLength();//根据响应获取文件大小 if (this.fileSize <= 0) throw new RuntimeException("无法获知文件大小 "); if (is == null) throw new RuntimeException("stream is null"); FileOutputStream fos = new FileOutputStream(path+filename); //把数据存入路径+文件名 byte buf[] = new byte[1024]; downLoadFileSize = 0; sendMsg(0); do { //循环读取 int numread = is.read(buf); if (numread == -1) { break; } fos.write(buf, 0, numread); downLoadFileSize += numread; sendMsg(1);//更新进度条 } while (true); sendMsg(2);//通知下载完成 try { is.close(); } catch (Exception ex) { Log.e("tag", "error: " + ex.getMessage(), ex); } } private void sendMsg(int flag) { Message msg = new Message(); msg.what = flag; handler.sendMessage(msg); } }