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嗨,我正在尝试从 [http://code.google.com/p/jquery-stream/wiki/ChatExample][1] 实现 java servlet 3.0 聊天示例。它在本地主机上运行正常,但是当上传到远程服务器时,流不会打开/启动或发送消息。我错过了什么?请帮忙。

<!--client side-->
<html>
    <head>
        <title>Chat - Servlet 3</title>
        <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
        <script type="text/javascript" src="jquery-1.8.2.js"></script>
        <script type="text/javascript" src="jquery.stream-1.2.js"></script>
        <script type="text/javascript">
            $.stream.setup({enableXDR: true});

            var chat = {
                lastUsername: "Donghwan Kim",
                username: $.trim(window.prompt("Username?")) || "Anonymous" + $(window).width()
            };

            $(function() {
                $.stream("chat", {
                    type: "http",
                    dataType: "json",
                    context: $("#content")[0],
                    open: function(event, stream) {
                        stream.send({username: chat.username, message: "Hello"});
                    },
                    message: function(event) {
                        if (chat.lastUsername !== event.data.username) {
                            $("<p />").addClass("user").text(chat.lastUsername = event.data.username).appendTo(this);
                        }

                        $("<p />").addClass("message").text(event.data.message).appendTo(this);
                        this.scrollTop = this.scrollHeight;
                    }
                });

                $("#editor .user").text(chat.username);
                $("#editor .message").keyup(function(event) {
                    if (event.which === 13 && $.trim(this.value)) {
                        $.stream().send({username: chat.username, message: this.value});
                        this.value = "";
                    }
                });
            });
        </script>
    </head>
    <body>
        <div id="content" class="content">
            <p class="user"></p>
            <p class="message"></p>
        </div>
        <div id="editor" class="editor">
            <p class="user"></p>
            <form action="#" onsubmit="return false;">
                <input class="message" type="text" />
            </form>
        </div>
    </body>
</html>



//server side
package com.chatty;

import com.google.gson.Gson;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.UUID;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.LinkedBlockingQueue;
import javax.servlet.AsyncContext;
import javax.servlet.AsyncEvent;
import javax.servlet.AsyncListener;
import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

@WebServlet(urlPatterns = "/chat", asyncSupported = true)
public class ChatServlet extends HttpServlet {

    private static final long serialVersionUID = -277914015930424042L;

    private Map<String, AsyncContext> asyncContexts = new ConcurrentHashMap<String, AsyncContext>();
    private BlockingQueue<String> messages = new LinkedBlockingQueue<String>();
    private Thread notifier = new Thread(new Runnable() {
        public void run() {
            while (true) {
                try {
                    // Waits until a message arrives
                    String message = messages.take();

                    // Sends the message to all the AsyncContext's response
                    for (AsyncContext asyncContext : asyncContexts.values()) {
                        try {
                            sendMessage(asyncContext.getResponse().getWriter(), message);
                        } catch (Exception e) {
                            asyncContexts.values().remove(asyncContext);
                        }
                    }
                } catch (InterruptedException e) {
                    break;
                }
            }
        }
    });

    private void sendMessage(PrintWriter writer, String message) throws IOException {
        // default message format is message-size ; message-data ;
        writer.print(message.length());
        writer.print(";");
        writer.print(message);
        writer.print(";");
        writer.flush();
    }

    @Override
    public void init(ServletConfig config) throws ServletException {
        super.init(config);
        notifier.start();
    }

    // GET method is used to establish a stream connection
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {

        // Content-Type header
        response.setContentType("text/plain");
        response.setCharacterEncoding("utf-8");

        // Access-Control-Allow-Origin header
        response.setHeader("Access-Control-Allow-Origin", "*");

        PrintWriter writer = response.getWriter();

        // Id
        final String id = UUID.randomUUID().toString();
        writer.print(id);
        writer.print(';');

        // Padding
        for (int i = 0; i < 1024; i++) {
            writer.print(' ');
        }
        writer.print(';');
        writer.flush();

        final AsyncContext ac = request.startAsync();
        ac.addListener(new AsyncListener() {
            public void onComplete(AsyncEvent event) throws IOException {
                asyncContexts.remove(id);
            }

            public void onTimeout(AsyncEvent event) throws IOException {
                asyncContexts.remove(id);
            }

            public void onError(AsyncEvent event) throws IOException {
                asyncContexts.remove(id);
            }

            public void onStartAsync(AsyncEvent event) throws IOException {

            }
        });
        asyncContexts.put(id, ac);
    }

    // POST method is used to communicate with the server
    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        request.setCharacterEncoding("utf-8");

        AsyncContext ac = asyncContexts.get(request.getParameter("metadata.id"));
        if (ac == null) {
            return;
        }

        // close-request
        if ("close".equals(request.getParameter("metadata.type"))) {
            ac.complete();
            return;
        }

        // send-request
        Map<String, String> data = new LinkedHashMap<String, String>();
        data.put("username", request.getParameter("username"));
        data.put("message", request.getParameter("message"));

        try {
            messages.put(new Gson().toJson(data));
        } catch (InterruptedException e) {
            throw new IOException(e);
        }
    }

    @Override
    public void destroy() {
        messages.clear();
        asyncContexts.clear();
        notifier.interrupt();
    }

}
4

1 回答 1

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似乎指定了错误的 URL(例如“聊天”)。

Fe 如果在本地环境中它可以很好地解析http://localhost:8080/chat,但它似乎与远程服务器有问题。如果您的索引页面位于“聊天”servlet 之外的其他位置,则可能是这样。

http://example.com/pages/index.html调用http://example.com/pages/chat

同时servlet的实际位置在 http://example.com/chat

您可以通过调查 Firebug 的 NET 选项卡或 Chrome 开发人员工具栏来检查它:检查正在调用哪个 URL。

于 2012-11-20T09:59:26.323 回答