java 监听文件或文件夹变化
今天遇到一个新需求，当从服务器下载文件后用指定的本地程序打开，不知道何时文件下载完成，只能考虑监听文件夹，当有新文件创建的时候打开指定程序。
在此给出一个完整的下载和打开过程：
1、下载文件
jsp页面
1 <body> 2 <div> 3 <a href="<%=basePath%>/user/downLoadFile?fileName=proPlan.DWG" >点击下载</a> 4 </div> 5 </body>
java代码
1 public static void downLoadtFile(HttpServletResponse response, File file) throws IOException 2 { 3 response.reset(); 4 response.setContentType("application/vnd.ms-excel;charset=UTF-8"); 5 response.setHeader("Content-disposition", 6 "attachment; filename=" + new String(file.getName().getBytes(), "iso-8859-1")); 7 OutputStream outputStream = response.getOutputStream(); 8 InputStream in = new FileInputStream(file); 9 byte[] b = new byte[1024]; 10 int len = 0; 11 while ((len = in.read(b)) > 0) 12 { 13 outputStream.write(b, 0, len); 14 } 15 outputStream.write(b); 16 outputStream.flush(); 17 in.close(); 18 }
2、监听文件夹，执行打开程序
1 package demo; 2 3 import java.io.IOException; 4 import java.nio.file.FileSystems; 5 import java.nio.file.Path; 6 import java.nio.file.Paths; 7 import java.nio.file.StandardWatchEventKinds; 8 import java.nio.file.WatchEvent; 9 import java.nio.file.WatchKey; 10 import java.nio.file.WatchService; 11 import java.util.List; 12 import java.util.concurrent.ExecutorService; 13 import java.util.concurrent.Executors; 14 15 public class FolderListener { 16 private static ExecutorService fixedThreadPool = Executors.newCachedThreadPool(); 17 private WatchService ws; 18 private String listenerPath; 19 private FolderListener(String path) { 20 try { 21 ws = FileSystems.getDefault().newWatchService(); 22 this.listenerPath = path; 23 start(); 24 } catch (IOException e) { 25 e.printStackTrace(); 26 } 27 } 28 29 private void start() { 30 fixedThreadPool.execute(new Listner(ws,this.listenerPath)); 31 } 32 33 public static void addListener(String path) throws IOException { 34 FolderListener resourceListener = new FolderListener(path); 35 Path p = Paths.get(path); 36 //注册监听事件，文件的修改、删除和创建 37 p.register(resourceListener.ws, 38 StandardWatchEventKinds.ENTRY_MODIFY, 39 StandardWatchEventKinds.ENTRY_DELETE, 40 StandardWatchEventKinds.ENTRY_CREATE); 41 } 42 43 44 public static void main(String[] args) throws IOException { 45 //监听下载目录的变化 46 FolderListener.addListener("C:\\Users\\Administrator\\Downloads\\"); 47 } 48 } 49 50 class Listner implements Runnable { 51 private WatchService service; 52 private String rootPath; 53 54 public Listner(WatchService service,String rootPath) { 55 this.service = service; 56 this.rootPath = rootPath; 57 } 58 59 public void run() { 60 try { 61 while(true){ 62 WatchKey watchKey = service.take(); 63 List<WatchEvent<?>> watchEvents = watchKey.pollEvents(); 64 for(WatchEvent<?> event : watchEvents){ 65 if(event.context().toString().endsWith(".DWG")) 66 // 根据事件类型采取不同的操作。。。。。。。 67 try { 68 System.out.println("["+rootPath+event.context()+"]文件发生了["+event.kind()+"]事件"+ event.count()); 69 String[] cmd = { "D:\\cad\\AutoCAD\\acad.exe", "C:\\Users\\Administrator\\Downloads\\" + event.context().toString() }; 70 Runtime.getRuntime().exec(cmd); 71 } catch (IOException e) { 72 e.printStackTrace(); 73 } 74 } 75 watchKey.reset(); 76 } 77 } catch (InterruptedException e) { 78 e.printStackTrace(); 79 }finally{ 80 System.out.println("fdsfsdf"); 81 try { 82 service.close(); 83 } catch (IOException e) { 84 e.printStackTrace(); 85 } 86 } 87 88 } 89 }
补充，除了执行指定exe，打开软件外还可以执行命令行
1 package demo; 2 3 import java.io.BufferedReader; 4 import java.io.InputStream; 5 import java.io.InputStreamReader; 6 7 public class Command { 8 9 public static void main(String[] args) { 10 String s = exeCmd("ipconfig"); 11 System.out.println(s); 12 } 13 14 public static String exeCmd(String commandStr) { 15 BufferedReader br = null; 16 StringBuilder sb = new StringBuilder(); 17 try { 18 Process p = Runtime.getRuntime().exec(commandStr); 19 br = new BufferedReader(new InputStreamReader(p.getInputStream(), "gb2312")); 20 // InputStream in = p.getInputStream(); 21 // byte[] b = new byte[1024]; 22 // int len = 0; 23 // while((len = in.read(b)) > 0){ 24 // sb.append(new String(b,"gb2312")).append("\n"); 25 // } 26 String line = null; 27 while ((line = br.readLine()) != null) { 28 sb.append(line).append("\n"); 29 } 30 } catch (Exception e) { 31 e.printStackTrace(); 32 } 33 finally 34 { 35 if (br != null) 36 { 37 try { 38 br.close(); 39 } catch (Exception e) { 40 e.printStackTrace(); 41 } 42 } 43 } 44 return sb.toString(); 45 } 46 }
