java 实现长链接Comet

测试环境Tomcat7

Servlet3以后才支持异步Servlet, Tomcat7中才支持. 其他jsp服务器没有测试.

1. Servlet

View Code

 1 import java.io.IOException;
 2 import java.util.Enumeration;
 3 import java.util.UUID;
 4
 5 import javax.servlet.ServletException;
 6 import javax.servlet.http.HttpServlet;
 7 import javax.servlet.http.HttpServletRequest;
 8 import javax.servlet.http.HttpServletResponse;
 9
10 import net.sf.json.JSONObject;
11
12 13 14
15 public class CometServlet extends HttpServlet {
16
17     @Override
18     protected void doGet(HttpServletRequest req, HttpServletResponse resp)
19             throws ServletException, IOException {
20         doPost(req, resp);
21     }
22
23     @Override
24     protected void doPost(HttpServletRequest req, HttpServletResponse resp)
25             throws ServletException, IOException {
26         System.out.println("CometServlet" + req);
27         Object UserId = req.getSession().getAttribute("UserId");
28         if (UserId == null) {
29             UserId = UUID.randomUUID().toString();
30             req.getSession().setAttribute("UserId", UserId);
31         }
32         System.out.println("Userid=" + UserId);
33         if (!req.isAsyncStarted()) {
34             req.startAsync();
35         }
36         resp.addHeader("Connection", "keep-alive");
37         resp.addHeader("Content-Type", "text/html; charset=utf-8");
38         Enumeration<String> names = req.getParameterNames();
39
40         JSONObject json = new JSONObject();
41         String key;
42         while (names.hasMoreElements()) {
43             key = names.nextElement();
44             json.put(key, req.getParameter(key));
45         }
46         AsynResult asynResult = new AsynResult(req.getAsyncContext(), json,
47                 UserId.toString());
48         AsynMsg.getInstance().AddClient(asynResult);
49     }
50 }

2. 同步消息缓存

View Code

 1 import javax.servlet.AsyncContext;
 2 import javax.servlet.ServletResponse;
 3
 4 import net.sf.json.JSONObject;
 5
 6 public class AsynResult {
 7     private AsyncContext context;
 8     private JSONObject json;
 9     private String userId;
10
11     public AsyncContext getContext() {
12         return context;
13     }
14
15     public JSONObject getJson() {
16         return json;
17     }
18
19     public String getUserId() {
20         return userId;
21     }
22
23     public AsynResult(AsyncContext context, JSONObject json, String userId) {
24         this.context = context;
25         this.json = json;
26         this.userId = userId;
27     }
28
29     public void send(JSONObject json) {
30         try {
31             ServletResponse rep = context.getResponse();
32             rep.setContentType("application/json;charset=UTF-8");
33             rep.setCharacterEncoding("UTF-8");
34             rep.getWriter().write(json.toString());
35         } catch (Exception e) {
36         }
37     }
38 }

3. 消息处理

View Code

 1 import java.util.HashMap;
 2 import java.util.Map;
 3
 4 import net.sf.json.JSONObject;
 5
 6  7
 8 public class AsynMsg {
 9     // List<AsynResult> clients = new ArrayList<AsynResult>();
10     private Map<String, AsynResult> clients = new HashMap<String, AsynResult>();
11     // region 实现该类的单例
12     private static final AsynMsg _Instance = new AsynMsg();
13     private static final String KEY = "msg";
14
15     private AsynMsg() {
16     }
17
18     public static AsynMsg getInstance() {
19         return _Instance;
20     }
21
22     public void AddClient(AsynResult result) {
23         String type = result.getJson().optString("type", "data");
24         String to = result.getJson().optString("to", null);
25         String user = result.getUserId();
26         String from = user;
27
28         if (type.equals("wait")) {
29             if("lott".equals(result.getJson().optString("msgType",""))){
30                 user = "lott";
31             }
32             clients.put(user, result);
33             try {
34                 synchronized (clients) {
35                     clients.wait();
36                 }
37             } catch (InterruptedException e) {
38                 e.printStackTrace();
39             }
40         } else {
41             if("".equals(type)){
42                 to = "lott";
43             }
44             JSONObject json = new JSONObject();
45             json.put(KEY, user + ":" + result.getJson().getString("asynMsg"));
46             // 将当前请求的内容输出到客户端
47             result.send(json);
48
49             // 否则将遍历所有已缓存的client,并将当前内容输出到客户端
50             sendMsg(user + ":" + result.getJson().getString("asynMsg"), from,
51                     to,type);
52         }
53
54     }
55
56     public void sendMsg(String content) {
57         sendMsg(content, "系统", null, "data");
58     }
59
60     // / <summary>
61     // / 遍歷所有客戶端， 將消息傳送給客戶端
62     // / </summary>
63     // / <param name="orderType"></param>
64     public void sendMsg(String content, String from, String to, String type) {
65         synchronized (clients) {
66             clients.notifyAll();
67         }
68         JSONObject json = new JSONObject();
69         json.put(KEY, content);
70         json.put("from", from);
71         json.put("to", to);
72         json.put("type", type);
73         System.out.println(json);
74         if (to == null || to.toUpperCase().equals("ALL")) {
75             for (AsynResult value : clients.values()) {
76                 value.send(json);
77                 value.getContext().complete();
78             }
79             // 清空所有缓存
80             clients.clear();
81         } else {
82             AsynResult value = clients.get(to);
83             value.send(json);
84             System.out.println(value.getContext().getRequest().isAsyncStarted());
85             if(value.getContext().getRequest().isAsyncStarted()){
86             value.getContext().complete();
87             }
88         }
89     }
90 }

4. 通过jsp建立长链接

http://localhost:8080/Comet/CometServlet?content=&type=wait

5. 通过jsp响应长链接

http://localhost:8080/Comet/json/home!SendMsg.do

6. 通过java程式模拟http建立长链接

View Code

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLEncoder;
import java.util.ArrayList;
import java.util.List;
import java.util.Random;
import java.util.ResourceBundle;import net.sf.json.JSONObject;public class HttpCometUtils {// private static String host = "http://localhost:8080/Comet/";private static String action = "json/home!SendMsg.do?msgType=ALL";protected static ResourceBundle projectBundle = ResourceBundle.getBundle("DataBaseServer");public static Thread CometThread = null;private static String host = projectBundle.getString("web_server");public static boolean isLogin = false;static {if (!host.endsWith("/")) {host += "/";}}public HttpCometUtils() {// host = "http://localhost:8080/Comet/";if (!host.endsWith("/")) {host += "/";}}/*** @param urlString* @param method* @param type* @param msg* @throws IOException*/public static void connectServer() {new Thread() {@Overridepublic void run() {int errorCount = 0;while (isLogin) {if (errorCount >= 10) {try {Thread.sleep(15000);} catch (InterruptedException e) {// TODO Auto-generated catch block
                            e.printStackTrace();break;}}URL url = null;HttpURLConnection urlConnection = null;try {String serverURL = host+ "CometServlet?content=&type=wait&msgType=lott";System.out.println(serverURL);url = new URL(serverURL);urlConnection = (HttpURLConnection) url.openConnection();urlConnection.setRequestMethod("GET");urlConnection.setDoOutput(true);urlConnection.setDoInput(true);urlConnection.setUseCaches(false);InputStream is = urlConnection.getInputStream();byte[] b = new byte[is.available()];is.read(b);String jsmsg = new String(b, "utf-8");System.out.println(jsmsg);if(jsmsg.equals("")){jsmsg = "{}";}JSONObject json = JSONObject.fromObject(jsmsg);Object obj = null;if (json.containsKey("type")) {obj = json.get("type");if (obj != null && "lott".equals(obj)) {json = (JSONObject) json.get("msg");if (json.containsKey("chatMsg")) {                                    System.out.println(json.get("chatMsg"));}}}errorCount = 0;} catch (MalformedURLException e) {errorCount++;// TODO Auto-generated catch block
                        e.printStackTrace();} catch (IOException e) {errorCount++;// TODO Auto-generated catch block
                        e.printStackTrace();} catch (Exception e) {errorCount++;e.printStackTrace();} finally {if (urlConnection != null) {urlConnection.disconnect();}}}}}.start();}public static void main(String[] args) {int x = new Random(System.currentTimeMillis()).nextInt(100);HttpCometUtils.isLogin = true;HttpCometUtils.connectServer();}
}

7. 通过java程式模拟http响应长链接

View Code

import java.io.IOException;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLEncoder;
import java.util.Random;
import java.util.ResourceBundle;public class HttpUtils {// private static String host = "http://localhost:8080/Comet/";private static String action = "json/home!SendMsg.do?msgType=ALL";protected static ResourceBundle projectBundle = ResourceBundle.getBundle("DataBaseServer");private static String host = "http://localhost:8080/Comet";//projectBundle.getString("web_server");static {if (!host.endsWith("/")) {host += "/";}}public HttpUtils() {if (!host.endsWith("/")) {host += "/";}}/*** @param urlString* @param method* @param type* @param msg* @throws IOException*/public static void send(final String type, final String asynMsg) {new Thread() {@Overridepublic void run() {URL url = null;HttpURLConnection urlConnection = null;try {StringBuffer param = new StringBuffer();param.append("&type=").append(type);param.append("&asynMsg=").append(URLEncoder.encode(asynMsg, "UTF-8"));String urlString = param.toString();String serverURL = host + action + urlString;System.out.println(serverURL);url = new URL(serverURL);urlConnection = (HttpURLConnection) url.openConnection();urlConnection.setRequestMethod("GET");// urlConnection.setDoOutput(true);// urlConnection.setDoInput(true);urlConnection.setUseCaches(false);System.out.println(urlConnection.getResponseMessage());} catch (MalformedURLException e) {// TODO Auto-generated catch block
                    e.printStackTrace();} catch (IOException e) {// TODO Auto-generated catch block
                    e.printStackTrace();} catch (Exception e) {e.printStackTrace();} finally {if (urlConnection != null) {urlConnection.disconnect();}}}}.start();}public static void main(String[] args) {int x = new Random(System.currentTimeMillis()).nextInt(100);HttpUtils.send("chat", "恭喜您中奖了.");}
}

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