android多任务下载的状态更新

本是古典何须时尚 2022-07-29 09:30 121阅读 0赞

对于下载任务，通常需要实时的更新任务进度

一般而言，最直接的方式是使用AsyncTask对进度进行实时更新

但对于多个任务并且界面切换后，AsyncTask并不能满足要求

此时需要使用service，进行独立的下载操作，而进度的更新可以通过不断的广播来更新需要展示的进度

代码片段

**\[java\]** [ view plain][view plain] [ copy][view plain] [ print][view plain] [?][view plain] [![在CODE上查看代码片][CODE]][CODE_CODE] [![派生到我的代码片][ico_fork.svg]][ico_fork.svg 1]

1.  package com.exam;  
2.    
3.  import java.io.File;  
4.  import java.io.IOException;  
5.  import java.io.InputStream;  
6.  import java.io.RandomAccessFile;  
7.  import java.net.HttpURLConnection;  
8.  import java.net.URL;  
9.  import java.util.concurrent.Executors;  
10. import java.util.concurrent.ThreadPoolExecutor;  
11.   
12. import android.app.Service;  
13. import android.content.Intent;  
14. import android.net.Uri;  
15. import android.os.Handler;  
16. import android.os.IBinder;  
17. import android.text.TextUtils;  
18. import android.util.Log;  
19.   
20. import com.exam.utils.FileUtils;  
21.   
22. public class DownloadService extends Service \{  
23.   
24.     private boolean stop;  
25.     public static final String ACTION\_DOWNLOAD = "com.exam.downloadservice";  
26.     private static ThreadPoolExecutor sExecutorService = (ThreadPoolExecutor) Executors  
27.             .newFixedThreadPool(3);  
28.     private String sAppId;  
29.     private Handler mHandler = new Handler() \{  
30.         public void handleMessage(android.os.Message msg) \{  
31.             int what = msg.what;  
32.             if (stop) \{  
33.                 return;  
34.             \}  
35.             if (what == 0) \{  
36.                 if (msg.obj != null && msg.obj instanceof Intent) \{  
37.                     Intent intent = (Intent) msg.obj;  
38.                     DownloadService.this.sendBroadcast(intent);  
39.                 \}  
40.             \} else if (what == 2) \{  
41.                 try \{  
42.                     Intent instIntent = new Intent(Intent.ACTION\_VIEW);  
43.                     instIntent.setFlags(Intent.FLAG\_ACTIVITY\_NEW\_TASK);  
44.                     instIntent.setDataAndType(  
45.                             Uri.fromFile(new File(msg.obj.toString())),  
46.                             "application/vnd.android.package-archive");  
47.                     startActivity(instIntent);  
48.                 \} catch (Exception e) \{  
49.                     e.printStackTrace();  
50.                 \}  
51.             \}  
52.         \}  
53.     \};  
54.   
55.     private class DownloadTask implements Runnable \{  
56.         private String mLocalPath = FileUtils.SDCARD\_BACKUP\_APP;  
57.         private String mAppId;  
58.         private String mDownloadUrl;  
59.         private String mLocalName = "tmp.apk";  
60.         private String mFileSize;  
61.         /\*\* 
62.          \* -2等待-1失败,0执行前, 1执行中 ,2成功 
63.          \*/  
64.         // private int flag = -2;   
65.   
66.         private long mTotalSize;  
67.         private long mDownloadedSize;  
68.         private long mDownloadedSpeed;  
69.         private int mProgress;  
70.   
71.         public DownloadTask(String appId, String appName, String downloadUrl,  
72.                 long size) \{  
73.             this.mAppId = appId;  
74.             this.mLocalName = appName + ".apk";  
75.             this.mDownloadUrl = downloadUrl;  
76.             this.mFileSize = FileUtils.getFormatSize(size);  
77.         \}  
78.   
79.         protected void onPreExecute(int flag) \{  
80.             mTotalSize = 0;  
81.             mDownloadedSize = 0;  
82.             mDownloadedSpeed = 1;  
83.             mProgress = 0;  
84.             publishProgress(flag);  
85.         \}  
86.   
87.         protected void onPostExecute(int flag) \{  
88.             publishProgress(flag);  
89.         \}  
90.   
91.         private void publishProgress(int flag) \{  
92.             if (mProgress > 100) \{  
93.                 mProgress = 100;  
94.             \}  
95.             if (mProgress < 0) \{  
96.                 mProgress = 0;  
97.             \}  
98.   
99.             StringBuffer bufferState = new StringBuffer();  
100.             bufferState.append(FileUtils.getFormatSize(mDownloadedSize))  
101.                     .append("/").append(mFileSize);  
102.   
103.             StringBuffer bufferSpeed = new StringBuffer();  
104.             bufferSpeed.append(FileUtils.getFormatSize(mDownloadedSpeed))  
105.                     .append("/s");  
106.   
107.             Intent intent = new Intent(ACTION\_DOWNLOAD);  
108.             intent.putExtra("appId", mAppId);  
109.             intent.putExtra("state", bufferState.toString());  
110.             intent.putExtra("speed", bufferSpeed.toString());  
111.             intent.putExtra("progress", this.mProgress);  
112.             // -2等待-1失败,0执行前, 1执行中 ,2成功   
113.             intent.putExtra("flag", flag);  
114.             mHandler.sendMessage(mHandler.obtainMessage(0, intent));  
115.             if (flag == 2) \{  
116.                 String path = FileUtils.SDCARD\_BACKUP\_APP + mLocalName;  
117.                 mHandler.sendMessage(mHandler.obtainMessage(2, path));  
118.             \}  
119.         \}  
120.   
121.         public void execute() \{  
122.             int flag = 0;  
123.             onPreExecute(flag);  
124.             flag = 1;  
125.             boolean result = downloadFile(flag);  
126.             if (result) \{  
127.                 flag = 2;  
128.             \} else \{  
129.                 flag = -1;  
130.             \}  
131.             onPostExecute(flag);  
132.         \}  
133.   
134.         private boolean downloadFile(int flag) \{  
135.             InputStream inputStream = null;  
136.             RandomAccessFile raf = null;  
137.             try \{  
138.                 // 检查文件夹是否存在，如果不存在就创建   
139.                 File dir = new File(mLocalPath);  
140.                 if (!dir.exists()) \{  
141.                     dir.mkdirs();  
142.                 \}  
143.   
144.                 File file = new File(mLocalPath, mLocalName);  
145.                 if (file.exists()) \{  
146.                     // downloadedSize = file.length();    
147.                     // raf.seek(downloadedSize);   
148.                     file.delete();  
149.                 \}  
150.                 raf = new RandomAccessFile(file, "rw");  
151.   
152.                 URL url = new URL(mDownloadUrl);  
153.                 HttpURLConnection urlConnection = (HttpURLConnection) url  
154.                         .openConnection();  
155.                 urlConnection.setRequestMethod("GET");  
156.                 // urlConnection   
157.                 // .setRequestProperty("RANGE", "bytes=" + downloadedSize);   
158.                 urlConnection.setDoOutput(true);  
159.                 urlConnection.connect();  
160.                 inputStream = urlConnection.getInputStream();  
161.                 mTotalSize = urlConnection.getContentLength();  
162.                 byte\[\] buffer = new byte\[1024\];  
163.                 int bufferLength = 0;  
164.   
165.                 // kb   
166.                 long beginTime = System.currentTimeMillis();  
167.                 long endTime = beginTime;  
168.                 long size = 0;  
169.                 while ((bufferLength = inputStream.read(buffer)) > 0) \{  
170.                     if (mAppId.equals(sAppId) || stop) \{  
171.                         inputStream.close();  
172.                         inputStream = null;  
173.                         sAppId = null;  
174.                         return false;  
175.                     \}  
176.                     raf.write(buffer, 0, bufferLength);  
177.                     mDownloadedSize += bufferLength;  
178.   
179.                     size += bufferLength;  
180.                     endTime = System.currentTimeMillis();  
181.                     if (endTime - beginTime >= 1000) \{  
182.                         // kb   
183.                         mDownloadedSpeed = size;  
184.                         mProgress = (int) (100 \* mDownloadedSize / mTotalSize);  
185.                         publishProgress(flag);  
186.   
187.                         beginTime = endTime;  
188.                         size = 0;  
189.                     \}  
190.   
191.                 \}  
192.                 raf.close();  
193.                 raf = null;  
194.                 inputStream.close();  
195.                 inputStream = null;  
196.             \} catch (Exception e) \{  
197.                 e.printStackTrace();  
198.                 return false;  
199.             \} finally \{  
200.                 try \{  
201.                     if (raf != null) \{  
202.                         raf.close();  
203.                         raf = null;  
204.                     \}  
205.                     if (inputStream != null) \{  
206.                         inputStream.close();  
207.                         inputStream = null;  
208.                     \}  
209.                 \} catch (IOException e) \{  
210.                     e.printStackTrace();  
211.                 \}  
212.             \}  
213.   
214.             return true;  
215.         \}  
216.   
217.         @Override  
218.         public void run() \{  
219.             execute();  
220.         \}  
221.     \}  
222.   
223.     private void execute(Runnable runnable) \{  
224.         sExecutorService.execute(runnable);  
225.     \}  
226.   
227.     @Override  
228.     public void onCreate() \{  
229.         super.onCreate();  
230.         stop = false;  
231.   
232.     \}  
233.   
234.     @Override  
235.     public void onDestroy() \{  
236.         super.onDestroy();  
237.         stop = true;  
238.         mHandler.removeMessages(0);  
239.         new Thread() \{  
240.             @Override  
241.             public void run() \{  
242.                 FileUtils.deleteFiles(new File(FileUtils.SDCARD\_BACKUP\_APP));  
243.             \}  
244.         \}.start();  
245.     \}  
246.   
247.     @Override  
248.     public int onStartCommand(Intent intent, int flags, int startId) \{  
249.         Log.v("DownloadService", "onStartCommand.intent=" + intent);  
250.         if (intent != null) \{  
251.             String appId = intent.getStringExtra("appId");  
252.             String appName = intent.getStringExtra("appName");  
253.             String downloadUrl = intent.getStringExtra("downloadUrl");  
254.             long fileSize = intent.getLongExtra("fileSize", 0);  
255.             boolean stop = intent.getBooleanExtra("stop", false);  
256.             if (!TextUtils.isEmpty(appId)) \{  
257.                 if (stop) \{  
258.                     sAppId = appId;  
259.                 \} else \{  
260.                     if (sExecutorService.getActiveCount() == 3) \{  
261.                         // 超出最大线程池数，提示稍后下载    
262.                         Intent intent2 = new Intent(ACTION\_DOWNLOAD);  
263.                         intent2.putExtra("appId", appId);  
264.                         intent2.putExtra("state", "");  
265.                         intent2.putExtra("speed", "");  
266.                         intent2.putExtra("progress", 0);  
267.                         // -2等待-1失败,0执行前, 1执行中 ,2成功   
268.                         intent2.putExtra("flag", -2);  
269.                         mHandler.sendMessage(mHandler.obtainMessage(0, intent2));  
270.                     \} else \{  
271.                         DownloadTask task = new DownloadTask(appId, appName,  
272.                                 downloadUrl, fileSize);  
273.                         execute(task);  
274.                     \}  
275.                 \}  
276.             \}  
277.         \}  
278.         return super.onStartCommand(intent, flags, startId);  
279.     \}  
280.   
281.     @Override  
282.     public IBinder onBind(Intent intent) \{  
283.         return null;  
284.     \}  
285. \}

package com.exam;
    
    import java.io.File;
    import java.io.IOException;
    import java.io.InputStream;
    import java.io.RandomAccessFile;
    import java.net.HttpURLConnection;
    import java.net.URL;
    import java.util.concurrent.Executors;
    import java.util.concurrent.ThreadPoolExecutor;
    
    import android.app.Service;
    import android.content.Intent;
    import android.net.Uri;
    import android.os.Handler;
    import android.os.IBinder;
    import android.text.TextUtils;
    import android.util.Log;
    
    import com.exam.utils.FileUtils;
    
    public class DownloadService extends Service {
    
    	private boolean stop;
    	public static final String ACTION_DOWNLOAD = "com.exam.downloadservice";
    	private static ThreadPoolExecutor sExecutorService = (ThreadPoolExecutor) Executors
    			.newFixedThreadPool(3);
    	private String sAppId;
    	private Handler mHandler = new Handler() {
    		public void handleMessage(android.os.Message msg) {
    			int what = msg.what;
    			if (stop) {
    				return;
    			}
    			if (what == 0) {
    				if (msg.obj != null && msg.obj instanceof Intent) {
    					Intent intent = (Intent) msg.obj;
    					DownloadService.this.sendBroadcast(intent);
    				}
    			} else if (what == 2) {
    				try {
    					Intent instIntent = new Intent(Intent.ACTION_VIEW);
    					instIntent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
    					instIntent.setDataAndType(
    							Uri.fromFile(new File(msg.obj.toString())),
    							"application/vnd.android.package-archive");
    					startActivity(instIntent);
    				} catch (Exception e) {
    					e.printStackTrace();
    				}
    			}
    		}
    	};
    
    	private class DownloadTask implements Runnable {
    		private String mLocalPath = FileUtils.SDCARD_BACKUP_APP;
    		private String mAppId;
    		private String mDownloadUrl;
    		private String mLocalName = "tmp.apk";
    		private String mFileSize;
    		/**
    		 * -2等待-1失败,0执行前, 1执行中 ,2成功
    		 */
    		// private int flag = -2;
    
    		private long mTotalSize;
    		private long mDownloadedSize;
    		private long mDownloadedSpeed;
    		private int mProgress;
    
    		public DownloadTask(String appId, String appName, String downloadUrl,
    				long size) {
    			this.mAppId = appId;
    			this.mLocalName = appName + ".apk";
    			this.mDownloadUrl = downloadUrl;
    			this.mFileSize = FileUtils.getFormatSize(size);
    		}
    
    		protected void onPreExecute(int flag) {
    			mTotalSize = 0;
    			mDownloadedSize = 0;
    			mDownloadedSpeed = 1;
    			mProgress = 0;
    			publishProgress(flag);
    		}
    
    		protected void onPostExecute(int flag) {
    			publishProgress(flag);
    		}
    
    		private void publishProgress(int flag) {
    			if (mProgress > 100) {
    				mProgress = 100;
    			}
    			if (mProgress < 0) {
    				mProgress = 0;
    			}
    
    			StringBuffer bufferState = new StringBuffer();
    			bufferState.append(FileUtils.getFormatSize(mDownloadedSize))
    					.append("/").append(mFileSize);
    
    			StringBuffer bufferSpeed = new StringBuffer();
    			bufferSpeed.append(FileUtils.getFormatSize(mDownloadedSpeed))
    					.append("/s");
    
    			Intent intent = new Intent(ACTION_DOWNLOAD);
    			intent.putExtra("appId", mAppId);
    			intent.putExtra("state", bufferState.toString());
    			intent.putExtra("speed", bufferSpeed.toString());
    			intent.putExtra("progress", this.mProgress);
    			// -2等待-1失败,0执行前, 1执行中 ,2成功
    			intent.putExtra("flag", flag);
    			mHandler.sendMessage(mHandler.obtainMessage(0, intent));
    			if (flag == 2) {
    				String path = FileUtils.SDCARD_BACKUP_APP + mLocalName;
    				mHandler.sendMessage(mHandler.obtainMessage(2, path));
    			}
    		}
    
    		public void execute() {
    			int flag = 0;
    			onPreExecute(flag);
    			flag = 1;
    			boolean result = downloadFile(flag);
    			if (result) {
    				flag = 2;
    			} else {
    				flag = -1;
    			}
    			onPostExecute(flag);
    		}
    
    		private boolean downloadFile(int flag) {
    			InputStream inputStream = null;
    			RandomAccessFile raf = null;
    			try {
    				// 检查文件夹是否存在，如果不存在就创建
    				File dir = new File(mLocalPath);
    				if (!dir.exists()) {
    					dir.mkdirs();
    				}
    
    				File file = new File(mLocalPath, mLocalName);
    				if (file.exists()) {
    					// downloadedSize = file.length();
    					// raf.seek(downloadedSize);
    					file.delete();
    				}
    				raf = new RandomAccessFile(file, "rw");
    
    				URL url = new URL(mDownloadUrl);
    				HttpURLConnection urlConnection = (HttpURLConnection) url
    						.openConnection();
    				urlConnection.setRequestMethod("GET");
    				// urlConnection
    				// .setRequestProperty("RANGE", "bytes=" + downloadedSize);
    				urlConnection.setDoOutput(true);
    				urlConnection.connect();
    				inputStream = urlConnection.getInputStream();
    				mTotalSize = urlConnection.getContentLength();
    				byte[] buffer = new byte[1024];
    				int bufferLength = 0;
    
    				// kb
    				long beginTime = System.currentTimeMillis();
    				long endTime = beginTime;
    				long size = 0;
    				while ((bufferLength = inputStream.read(buffer)) > 0) {
    					if (mAppId.equals(sAppId) || stop) {
    						inputStream.close();
    						inputStream = null;
    						sAppId = null;
    						return false;
    					}
    					raf.write(buffer, 0, bufferLength);
    					mDownloadedSize += bufferLength;
    
    					size += bufferLength;
    					endTime = System.currentTimeMillis();
    					if (endTime - beginTime >= 1000) {
    						// kb
    						mDownloadedSpeed = size;
    						mProgress = (int) (100 * mDownloadedSize / mTotalSize);
    						publishProgress(flag);
    
    						beginTime = endTime;
    						size = 0;
    					}
    
    				}
    				raf.close();
    				raf = null;
    				inputStream.close();
    				inputStream = null;
    			} catch (Exception e) {
    				e.printStackTrace();
    				return false;
    			} finally {
    				try {
    					if (raf != null) {
    						raf.close();
    						raf = null;
    					}
    					if (inputStream != null) {
    						inputStream.close();
    						inputStream = null;
    					}
    				} catch (IOException e) {
    					e.printStackTrace();
    				}
    			}
    
    			return true;
    		}
    
    		@Override
    		public void run() {
    			execute();
    		}
    	}
    
    	private void execute(Runnable runnable) {
    		sExecutorService.execute(runnable);
    	}
    
    	@Override
    	public void onCreate() {
    		super.onCreate();
    		stop = false;
    
    	}
    
    	@Override
    	public void onDestroy() {
    		super.onDestroy();
    		stop = true;
    		mHandler.removeMessages(0);
    		new Thread() {
    			@Override
    			public void run() {
    				FileUtils.deleteFiles(new File(FileUtils.SDCARD_BACKUP_APP));
    			}
    		}.start();
    	}
    
    	@Override
    	public int onStartCommand(Intent intent, int flags, int startId) {
    		Log.v("DownloadService", "onStartCommand.intent=" + intent);
    		if (intent != null) {
    			String appId = intent.getStringExtra("appId");
    			String appName = intent.getStringExtra("appName");
    			String downloadUrl = intent.getStringExtra("downloadUrl");
    			long fileSize = intent.getLongExtra("fileSize", 0);
    			boolean stop = intent.getBooleanExtra("stop", false);
    			if (!TextUtils.isEmpty(appId)) {
    				if (stop) {
    					sAppId = appId;
    				} else {
    					if (sExecutorService.getActiveCount() == 3) {
    						// 超出最大线程池数，提示稍后下载
    						Intent intent2 = new Intent(ACTION_DOWNLOAD);
    						intent2.putExtra("appId", appId);
    						intent2.putExtra("state", "");
    						intent2.putExtra("speed", "");
    						intent2.putExtra("progress", 0);
    						// -2等待-1失败,0执行前, 1执行中 ,2成功
    						intent2.putExtra("flag", -2);
    						mHandler.sendMessage(mHandler.obtainMessage(0, intent2));
    					} else {
    						DownloadTask task = new DownloadTask(appId, appName,
    								downloadUrl, fileSize);
    						execute(task);
    					}
    				}
    			}
    		}
    		return super.onStartCommand(intent, flags, startId);
    	}
    
    	@Override
    	public IBinder onBind(Intent intent) {
    		return null;
    	}
    }

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