Java 实现 web服务器

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import java.io.*;import java.net.*;import java.util.*;// Chapter 8, Listing 3public class WebServerDemo {// Directory of HTML pages and other filesprotected String docroot;// Port number of web serverprotected int port;// Socket for the web serverprotected ServerSocket ss;// Handler for a HTTP requestclass Handler extends Thread {protected Socket socket;protected PrintWriter pw;protected BufferedOutputStream bos;protected BufferedReader br;protected File docroot;public Handler(Socket _socket, String _docroot) throws Exception {socket = _socket;// Get the absolute directory of the filepathdocroot = new File(_docroot).getCanonicalFile();}public void run() {try {// Prepare our readers and writersbr = new BufferedReader(new InputStreamReader(socket.getInputStream()));bos = new BufferedOutputStream(socket.getOutputStream());pw = new PrintWriter(new OutputStreamWriter(bos));// Read HTTP request from user (hopefully GET /file...... )String line = br.readLine();// Shutdown any further inputsocket.shutdownInput();if (line == null) {socket.close();return;}if (line.toUpperCase().startsWith("GET")) {// Eliminate any trailing ? data, such as for a CGI GET// requestStringTokenizer tokens = new StringTokenizer(line, " ?");tokens.nextToken();String req = tokens.nextToken();// If a path character / or / is not present, add it to the// document root// and then add the file request, to form a full filenameString name;if (req.startsWith("/") || req.startsWith("//"))name = this.docroot + req;elsename = this.docroot + File.separator + req;// Get absolute file pathFile file = new File(name).getCanonicalFile();// Check to see if request doesn't start with our document// root ....if (!file.getAbsolutePath().startsWith(this.docroot.getAbsolutePath())) {pw.println("HTTP/1.0 403 Forbidden");pw.println();}// ... if it's missing .....else if (!file.exists()) {pw.println("HTTP/1.0 404 File Not Found");pw.println();}// ... if it can't be read for security reasons ....else if (!file.canRead()) {pw.println("HTTP/1.0 403 Forbidden");pw.println();}// ... if its actually a directory, and not a file ....else if (file.isDirectory()) {sendDir(bos, pw, file, req);}// ... or if it's really a fileelse {sendFile(bos, pw, file.getAbsolutePath());}}// If not a GET request, the server will not support itelse {pw.println("HTTP/1.0 501 Not Implemented");pw.println();}pw.flush();bos.flush();} catch (Exception e) {e.printStackTrace();}try {socket.close();} catch (Exception e) {e.printStackTrace();}}protected void sendFile(BufferedOutputStream bos, PrintWriter pw,String filename) throws Exception {try {java.io.BufferedInputStream bis = new java.io.BufferedInputStream(new FileInputStream(filename));byte[] data = new byte[10 * 1024];int read = bis.read(data);pw.println("HTTP/1.0 200 Okay");pw.println();pw.flush();bos.flush();while (read != -1) {bos.write(data, 0, read);read = bis.read(data);}bos.flush();} catch (Exception e) {pw.flush();bos.flush();}}protected void sendDir(BufferedOutputStream bos, PrintWriter pw,File dir, String req) throws Exception {try {pw.println("HTTP/1.0 200 Okay");pw.println();pw.flush();pw.print("<html><head><title>Directory of ");pw.print(req);pw.print("</title></head><body><h1>Directory of ");pw.print(req);pw.println("</h1><table border=/"0/">");File[] contents = dir.listFiles();for (int i = 0; i < contents.length; i++) {pw.print("<tr>");pw.print("<td><a href="/" mce_href="/""");pw.print(req);pw.print(contents[i].getName());if (contents[i].isDirectory())pw.print("/");pw.print("/">");if (contents[i].isDirectory())pw.print("Dir -> ");pw.print(contents[i].getName());pw.print("</a></td>");pw.println("</tr>");}pw.println("</table></body></html>");pw.flush();} catch (Exception e) {pw.flush();bos.flush();}}}// Check that a filepath has been specified and a port numberprotected void parseParams(String[] args) throws Exception {switch (args.length) {case 1:case 0:System.err.println("Syntax: <jvm> " + this.getClass().getName()+ " docroot port");System.exit(0);default:this.docroot = args[0];this.port = Integer.parseInt(args[1]);break;}}public WebServerDemo(String[] args) throws Exception {System.out.println("Checking for paramters");// Check for command line parametersparseParams(args);System.out.print("Starting web server...... ");// Create a new server socketthis.ss = new ServerSocket(this.port);System.out.println("OK");for (;;) {// Accept a new socket connection from our server socketSocket accept = ss.accept();// Start a new handler instance to process the requestnew Handler(accept, docroot).start();}}// Start an instance of the web server runningpublic static void main(String[] args) throws Exception {WebServerDemo webServerDemo = new WebServerDemo(args);}}