<ProgressBar
android:id="@+id/progressBar"
style="?android:attr/progressBarStyleHorizontal"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:max="100" />
<TextView
android:id="@+id/textView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@+id/progressBar"
android:layout_centerHorizontal="true"
android:layout_marginTop="24dp"
android:text="TextView" />
<ImageView
android:id="@+id/imageView"
android:layout_marginTop="24dp"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_below="@+id/textView"
android:contentDescription="@string/app_name"
android:src="@drawable/ic_launcher" />
</RelativeLayout></pre>
接下來的主Activity代碼：
public class MainActivity extends Activity {
ProgressBar pb;
TextView tv;
ImageView imageView;
int fileSize;
int downLoadFileSize;
String fileEx,fileNa,filename;
//用來接收線程發送來的文件下載量，進行UI界面的更新
private Handler handler = new Handler(){
@Override
public void handleMessage(Message msg)
{//定義一個Handler，用于處理下載線程與UI間通訊
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(MainActivity.this, "文件下載完成", Toast.LENGTH_SHORT).show();
FileInputStream fis = null;
try {
fis = new FileInputStream(Environment.getExternalStorageDirectory() + File.separator + "/ceshi/" + filename);
} catch (FileNotFoundException e) {
e.printStackTrace();
}
Bitmap bitmap = BitmapFactory.decodeStream(fis); ///把流轉化為Bitmap圖
imageView.setImageBitmap(bitmap);
break;
case -1:
String error = msg.getData().getString("error");
Toast.makeText(MainActivity.this, error, Toast.LENGTH_SHORT).show();
break;
}
}
super.handleMessage(msg);
}
};
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
pb=(ProgressBar)findViewById(R.id.progressBar);
tv=(TextView)findViewById(R.id.textView);
imageView = (ImageView) findViewById(R.id.imageView);
tv.setText("0%");
new Thread(){
public void run(){
try {
//下載文件，參數：第一個URL，第二個存放路徑
down_file("http://cdnq.duitang.com/uploads/item/201406/15/20140615203435_ABQMa.jpeg", Environment.getExternalStorageDirectory() + File.separator + "/ceshi/");
} catch (ClientProtocolException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}.start();
}
/**
* 文件下載
* @param url：文件的下載地址
* @param path：文件保存到本地的地址
* @throws IOException
*/
public void down_file(String url,String path) throws IOException{
//下載函數
filename=url.substring(url.lastIndexOf("/") + 1);
//獲取文件名
URL myURL = new URL(url);
URLConnection conn = myURL.openConnection();
conn.connect();
InputStream is = conn.getInputStream();
this.fileSize = conn.getContentLength();//根據響應獲取文件大小
if (this.fileSize <= 0) throw new RuntimeException("無法獲知文件大小 ");
if (is == null) throw new RuntimeException("stream is null");
File file1 = new File(path);
File file2 = new File(path+filename);
if(!file1.exists()){
file1.mkdirs();
}
if(!file2.exists()){
file2.createNewFile();
}
FileOutputStream fos = new FileOutputStream(path+filename);
//把數據存入路徑+文件名
byte buf[] = new byte[1024];
downLoadFileSize = 0;
sendMsg(0);
do{
//循環讀取
int numread = is.read(buf);
if (numread == -1)
{
break;
}
fos.write(buf, 0, numread);
downLoadFileSize += numread;
sendMsg(1);//更新進度條
} while (true);
sendMsg(2);//通知下載完成
try{
is.close();
} catch (Exception ex) {
Log.e("tag", "error: " + ex.getMessage(), ex);
}
}
//在線程中向Handler發送文件的下載量，進行UI界面的更新
private void sendMsg(int flag)
{
Message msg = new Message();
msg.what = flag;
handler.sendMessage(msg);
}
}</pre>
最后一定要注意的是：在AndroidManifest.xml文件中，添加訪問網絡的權限
<uses-permission android:name="android.permission.INTERNET"/>
到這里關于Android文件下載動態顯示下載進度的小demo就為大家分享完畢，希望對大家的學習有所幫助。
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