Android文件下载之进度检测

ShaunaBinne 8年前

来自: http://www.cnblogs.com/AndroidJotting/p/5222442.html

近期因为项目的需要,研究了一下Android文件下载进度显示的功能实现,接下来就和大家一起分享学习一下,希望对广大初学者有帮助。先上效果图:

上方的蓝色进度条,会根据文件下载量的百分比进行加载,中部的文本控件用来现在文件下载的百分比,最下方的ImageView用来展示下载好的文件,项目的目的就是动态向用户展示文件的下载量。

下面看代码实现:首先是布局文件:

<RelativeLayout 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"      tools:context="${relativePackage}.${activityClass}" >        <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>

接下来的主Activity代码:

public class MainActivity extends Activity {     ProgressBar pb;      TextView tv;    ImageView imageView;      int fileSize;          int downLoadFileSize;          String fileEx,fileNa,filename;        //用来接收线程发送来的文件下载量,进行UI界面的更新      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(MainActivity.this, "文件下载完成", 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);  ///把流转化为Bitmap图                  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 {                   //下载文件,参数:第一个URL,第二个存放路径                   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();                 }          /**    * 文件下载    * @param url:文件的下载地址    * @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");           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);              }                 }                //在线程中向Handler发送文件的下载量,进行UI界面的更新      private void sendMsg(int flag)          {              Message msg = new Message();              msg.what = flag;              handler.sendMessage(msg);          }                 }

最后一定要注意的是:在AndroidManifest.xml文件中,添加访问网络的权限

<uses-permission android:name="android.permission.INTERNET"/>

到这里关于Android文件下载动态显示下载进度的小demo就为大家分享完毕,希望对大家的学习有所帮助。