java 监听文件或文件夹变化
程序员文章站
2023-04-05 09:31:24
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 java代码 2、监听文件夹，执行打开程序 1 package demo; 2 3 import ......
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 }