android文件下载进度条实现

最新推荐文章于 2024-09-09 09:13:41 发布

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最新推荐文章于 2024-09-09 09:13:41 发布

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分类专栏： android 文章标签：移动开发 xcode java

本文链接：https://blog.youkuaiyun.com/xiehongdong2009/article/details/84006928

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本文介绍了一个简单的Android应用示例，展示了如何实现文件下载过程中的进度条更新功能。该示例包括了使用自定义对话框展示进度条的方法，并提供了一个用于下载文件的工具类。

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做了个小例子，是关于android文件下载过程中进度条的实现，有些地方还有不当的地方，其中文件下载部分是参考mars老师的代码的，有兴趣可以去关注一下mars老师，http://www.mars-droid.com

代码写的比较乱，建议去看看mars老师的视频。

多话不说直接上代码了：

main.xml页面布局文件：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    >
<TextView  
	android:id="@+id/textView"
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content" 
    android:text="@string/hello"
    />
<Button 
	android:id="@+id/downloadTextButton"
	android:layout_width="fill_parent"
	android:layout_height="wrap_content"
	android:text="下载文本文件"/>
<Button 
	android:id="@+id/downloadMp3Button"
	android:layout_width="fill_parent"
	android:layout_height="wrap_content"
	android:text="下载MP3文件"/>
<EditText 
	android:id="@+id/editText"
	android:layout_width="fill_parent"
	android:layout_height="wrap_content"
	android:hint="请出输入文字!"
	android:lines="3"/>
<Button 
	android:id="@+id/textButton"
	android:layout_width="fill_parent"
	android:layout_height="wrap_content"
	android:text="测试"/>
</LinearLayout>

DownloadActivity

public class DownloadActivity extends Activity {
	public static final int DIALOG_DOWNLOAD_PROGRESS = 0;
//	public int fileSize=0;
//	public int downloadFileSize=0;
	
	private TextView textView;
	private Button downloadTextButton;
	private Button downloadMp3Button;
	private Button textButton;
	private EditText editText;
	
	
	private ProgressDialog dialog = null;
	
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        downloadTextButton = (Button) this.findViewById(R.id.downloadTextButton);
        downloadMp3Button = (Button) this.findViewById(R.id.downloadMp3Button);
        //添加监听
        downloadTextButton.setOnClickListener(new DownloadTextButtonListener());
        downloadMp3Button.setOnClickListener(new DownloadMp3ButtonListener());
        
        textView = (TextView) this.findViewById(R.id.textView);
        editText = (EditText) this.findViewById(R.id.editText);
        textButton = (Button) this.findViewById(R.id.textButton);
        textButton.setOnClickListener(new OnClickListener(){

			@Override
			public void onClick(View v) {
				textView.setText(editText.getText().toString());
				Toast.makeText(DownloadActivity.this, textView.getText().toString(), Toast.LENGTH_LONG);
			}
        	
        });
        
    }
    
	@Override
	protected Dialog onCreateDialog(int id) {
		switch(id){
			case DIALOG_DOWNLOAD_PROGRESS:
				dialog = new ProgressDialog(this);
				dialog.setMessage("downloading…");
				dialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
				dialog.setCancelable(false);
				dialog.show();
				return dialog;
			default:
				return null;
		}
	}
	
	private Handler handler = new Handler(){
		@Override
		public void handleMessage(Message msg) {
			if(!Thread.currentThread().isInterrupted()){
				switch(msg.what){
					case 0:
						dialog.setMax(msg.arg1);
						break;
					case 1:
						dialog.setProgress(msg.arg1);
						break;
					case 2:
						dialog.dismiss();
						break;
					case -1:
						String error = msg.getData().getString("error");
			            Toast.makeText(DownloadActivity.this, error, 1).show();
						break;
					
				}
			}
			super.handleMessage(msg);
		}
	};

	class DownloadTextButtonListener implements OnClickListener{

		/* (non-Javadoc)
		 * @see android.view.View.OnClickListener#onClick(android.view.View)
		 */
		@Override
		public void onClick(View v) {
			// TODO Auto-generated method stub
//			HttpDownloader httpDownloader = new HttpDownloader();
//			String text = httpDownloader.download("http://zhangmenshiting.baidu.com/data/music/5789992/%E8%8D%B7%E5%A1%98%E6%9C%88%E8%89%B2.mp3?xcode=732ac4f76aeff611f08f3bb5c5f0aafe");
		}
    	
    }
    
    class DownloadMp3ButtonListener implements OnClickListener{

		/* (non-Javadoc)
		 * @see android.view.View.OnClickListener#onClick(android.view.View)
		 */
		@Override
		public void onClick(View v) {
			//打开进度条
			showDialog(DIALOG_DOWNLOAD_PROGRESS);
			
			Thread t = new Thread(runnable);
			t.start();
		}
    	
    }
    
    Runnable runnable = new Runnable(){
		@Override
		public void run() {
			HttpDownloader httpDownloader = new HttpDownloader();
			
			int result = httpDownloader.download(DownloadActivity.this,"http://zhangmenshiting.baidu.com/data/music/5935874/%E6%BA%9C%E6%BA%9C%E7%9A%84%E6%83%85%E6%AD%8C.mp3?xcode=54e0a53865de98f9ba842c53eb1bf508", "music/", "e.mp3");
			
			System.out.println(result);
			String str =null;
			if(result == 0){
				str = "成功！";
			}else if(result == 1){
				str = "文件已存在！";
			}else{
				str = "失败！";
			}
			
//			Toast.makeText(DownloadActivity.this, "下载结果"+str, Toast.LENGTH_LONG).show();
		}
    	
    };
    
    public void sendMsg(int flag,int value){
    	Message message = new Message();
    	message.what = flag;
    	message.arg1 = value;
    	handler.sendMessage(message);
    }
    
}

下面两个为下载的工具类：

FileUtils.java

public class FileUtils {
	private String SDPATH;
	/**
	 * 
	 */
	public FileUtils() {
		// TODO Auto-generated constructor stub
		//获得当前外部存储设备的目录
		SDPATH = Environment.getExternalStorageDirectory()+"/";
	}
	/**
	 * 在SD卡上创建文件
	 * @param fileName
	 * @return
	 */
	public File createSdFile(String fileName){
		File file = new File(SDPATH + fileName);
		try {
			file.createNewFile();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		
		return file;
	}
	
	/**
	 * 创建SD卡目录
	 * @param dirName
	 * @return
	 */
	public File createSDDir(String dirName){
		File file = new File(SDPATH + dirName);
		file.mkdir();
		
		return file;
	}
	
	public boolean isFileExist(String fileName){
		File file = new File(SDPATH + fileName);
		
		return file.exists();
		
	}
	
	public File writeToSDFromInput(Context context,String path,String fileName,InputStream input){
		File file = null;
		OutputStream output = null;
		
		try {
			createSDDir(path);
			file = createSdFile(path + fileName);
			output = new FileOutputStream(file);
			
			byte[] buffer = new byte[4 * 1024];
			int total = 0;
			while((input.read(buffer)) != -1){
				total = total + buffer.length;
				output.write(buffer);
				//更新下载进度条
				((DownloadActivity)context).sendMsg(1,total);
			}
			output.flush();
		} catch (FileNotFoundException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}finally{
			try {
				output.close();
			} catch (IOException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}
		//下载完成
		((DownloadActivity)context).sendMsg(2,0);
		return file;
	}
	
}

HttpDownloader.java

public class HttpDownloader {
	private URL url = null;
	/**
	 * 根据URL下载文件，前提是文件当中的内容为文本，返回值就是文件当中的内容
	 * @param urlStr
	 * @return
	 */
	public String download(String urlStr){
		
		StringBuffer buffer = new StringBuffer();
		String line = null;
		BufferedReader reader = null;
		
		try {
			url = new URL(urlStr);
			try {
				HttpURLConnection conn = (HttpURLConnection) url.openConnection();
				reader = new BufferedReader(new InputStreamReader(conn.getInputStream()));
				while ((line = reader.readLine()) != null) {
					buffer.append(line);
				}
			} catch (IOException e) {
				Log.e("io", "HttpURLConnection -> IOException");
				e.printStackTrace();
			}
			
		} catch (MalformedURLException e) {
			Log.e("url","url -> MalformedURLException");
			e.printStackTrace();
		}finally{
			try {
				reader.close();
			} catch (IOException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}
		return buffer.toString();
		
	}
	/**
	 * 该函数返回整形： -1代表下载出错，0代表下载成功，1代表下载文件已存在
	 * @param urlStr
	 * @param path
	 * @param fileName
	 * @return
	 */
	public int download(Context context,String urlStr,String path,String fileName){
		InputStream input = null;
		FileUtils fileUtils = new FileUtils();
		if(fileUtils.isFileExist(path + fileName)){
			((DownloadActivity)context).sendMsg(2,0);
			return 1;
		}else{
			try {
				input = getInputStreamFromUrl(context,urlStr);
			} catch (IOException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
			File resultFile = fileUtils.writeToSDFromInput(context,path, fileName, input);
			if(resultFile == null){
				return -1;
			}
		}
		return 0;
	}
	
	public InputStream getInputStreamFromUrl(Context context,String urlStr) throws IOException{
		url = new URL(urlStr);
		HttpURLConnection conn = (HttpURLConnection) url.openConnection();
		
		InputStream s = conn.getInputStream();
		
		((DownloadActivity)context).sendMsg(0,conn.getContentLength());
		
		return s;
	}
}

别忘记添加：

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

下面是运行的结果图：

正在下载：

下载完成之后，我们在sdcard/music可以看到f.mp3文件

下面附上源码，可以自己修改，在例子中我是通过直接弹出的方式显示进度条的，这样在下载的时候我们就不能做其他的事情了，我们可以在布局文件中显示进度条，这样我们在下载的时候可以在文本框中输入一下内容，点击测试按钮之后文本框中的内容可以在上面的TextView中显示出来。

如果运行本例子，需要更改下载的url地址，我用的是百度的音乐下载，在测试中发现百度每次生成的连接只能下载一次。