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103 lines
2.9 KiB
103 lines
2.9 KiB
7 months ago
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package sample.evolve;
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import javassist.tools.web.*;
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import java.io.*;
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/**
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* A web server for demonstrating class evolution. It must be
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* run with a DemoLoader.
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*
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* If a html file /java.html is requested, this web server calls
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* WebPage.show() for constructing the contents of that html file
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* So if a DemoLoader changes the definition of WebPage, then
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* the image of /java.html is also changed.
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* Note that WebPage is not an applet. It is rather
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* similar to a CGI script or a servlet. The web server never
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* sends the class file of WebPage to web browsers.
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*
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* Furthermore, if a html file /update.html is requested, this web
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* server overwrites WebPage.class (class file) and calls update()
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* in VersionManager so that WebPage.class is loaded into the JVM
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* again. The new contents of WebPage.class are copied from
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* either sample/evolve/WebPage.class
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* or sample/evolve/sample/evolve/WebPage.class.
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*/
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public class DemoServer extends Webserver {
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public static void main(String[] args) throws IOException
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{
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if (args.length == 1) {
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DemoServer web = new DemoServer(Integer.parseInt(args[0]));
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web.run();
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}
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else
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System.err.println(
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"Usage: java sample.evolve.DemoServer <port number>");
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}
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public DemoServer(int port) throws IOException {
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super(port);
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htmlfileBase = "sample/evolve/";
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}
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private static final String ver0 = "sample/evolve/WebPage.class.0";
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private static final String ver1 = "sample/evolve/WebPage.class.1";
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private String currentVersion = ver0;
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public void doReply(InputStream in, OutputStream out, String cmd)
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throws IOException, BadHttpRequest
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{
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if (cmd.startsWith("GET /java.html ")) {
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runJava(out);
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return;
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}
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else if (cmd.startsWith("GET /update.html ")) {
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try {
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if (currentVersion == ver0)
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currentVersion = ver1;
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else
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currentVersion = ver0;
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updateClassfile(currentVersion);
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VersionManager.update("sample.evolve.WebPage");
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}
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catch (CannotUpdateException e) {
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logging(e.toString());
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}
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catch (FileNotFoundException e) {
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logging(e.toString());
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}
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}
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super.doReply(in, out, cmd);
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}
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private void runJava(OutputStream outs) throws IOException {
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OutputStreamWriter out = new OutputStreamWriter(outs);
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out.write("HTTP/1.0 200 OK\r\n\r\n");
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WebPage page = new WebPage();
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page.show(out);
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out.close();
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}
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/* updateClassfile() copies the specified file to WebPage.class.
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*/
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private void updateClassfile(String filename)
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throws IOException, FileNotFoundException
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{
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byte[] buf = new byte[1024];
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FileInputStream fin
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= new FileInputStream(filename);
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FileOutputStream fout
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= new FileOutputStream("sample/evolve/WebPage.class");
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for (;;) {
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int len = fin.read(buf);
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if (len >= 0)
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fout.write(buf, 0, len);
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else
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break;
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}
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}
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}
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