Android实现文件下载进度显示功能

时间:2022-11-19 10:36:53

和大家一起分享一下学习经验,如何实现android文件下载进度显示功能,希望对广大初学者有帮助。
先上效果图:

  Android实现文件下载进度显示功能

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:

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<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:

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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

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<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内容就为大家分享完毕,希望对大家的学习有所帮助。