java 监听文件或文件夹变化，java文件夹
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
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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 }
View Code
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 }
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