采用handle 实现下载图片带有进度条

这是采用handle+thread 实现图片的下载

不多说首先贴上

import java.io.BufferedInputStream; import java.io.BufferedOutputStream; import java.io.File; import java.io.FileOutputStream; import java.io.IOException; import java.io.InputStream; import java.net.MalformedURLException; import java.net.URL; import java.net.URLConnection; import android.app.Activity; import android.graphics.Bitmap; import android.graphics.BitmapFactory; import android.os.Bundle; import android.os.Handler; import android.os.Message; import android.view.View; import android.widget.ImageView; import android.widget.ProgressBar; /** * Handler来实现进度条 * @author ZXY * */ public class MainActivity extends Activity { private ImageView iv; private ProgressBar pb; private String urlStr = "http://www.bz55.com/uploads/allimg/150309/139-150309101F7.jpg"; private Handler handler = new Handler(){ //在主线程当中被回调 public void handleMessage(android.os.Message msg) { if (msg.what == 0) {//设置ProgressBar的max Bundle data = msg.getData(); pb.setMax(data.getInt("max")); }else if (msg.what == 1) {//增加ProgressBar的进度 Bundle data = msg.getData(); pb.setProgress(pb.getProgress() + data.getInt("progress")); }else if (msg.what == 2) {//显示图片资源 iv.setImageBitmap((Bitmap) msg.obj); } }; }; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); iv = (ImageView) findViewById(R.id.iv); pb = (ProgressBar) findViewById(R.id.pb); iv.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { new Thread(new Runnable() { @Override public void run() { try { URL url = new URL(urlStr); URLConnection conn = url.openConnection(); //获取资源的总大小 int totalLen = conn.getContentLength(); Message maxMsg = new Message(); maxMsg.what = 0; Bundle maxData = new Bundle(); maxData.putInt("max", totalLen); maxMsg.setData(maxData); handler.sendMessage(maxMsg); InputStream is = conn.getInputStream(); //声明缓冲区大小（8kb） byte[] buf = new byte[1024 * 8]; File file = new File("/mnt/sdcard/fengjing.jpg"); //如果图片不存在，则创建一个新的文件 if (!file.exists()) { file.createNewFile(); } //声明缓冲输出流 BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream(file)); //声明缓冲输入流 BufferedInputStream bis = new BufferedInputStream(is); int len = 0;//每次真实读取的长度 while((len = bis.read(buf)) != -1){ bos.write(buf, 0, len); Message progressMsg = new Message(); progressMsg.what = 1; Bundle progressData = new Bundle(); progressData.putInt("progress", len); progressMsg.setData(progressData); handler.sendMessage(progressMsg); } bos.flush(); bis.close(); bos.close(); Bitmap bmp = BitmapFactory.decodeFile(file.getAbsolutePath()); Message bmpMsg = new Message(); bmpMsg.what = 2; bmpMsg.obj = bmp; handler.sendMessage(bmpMsg); } catch (MalformedURLException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } } }).start(); } }); } } 

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context=".MainActivity" >

    <ProgressBar
        android:id="@+id/pb"
        style="?android:attr/progressBarStyleHorizontal"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content" />

    <ImageView
        android:id="@+id/iv"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:src="@drawable/ic_launcher" />

</LinearLayout>