Pushlets - java comet 開發紀錄
Pushlets - java comet
IDE：Eclipse
APServer：Tomcat
Java version：1.6
解壓縮後
/client：additional (non-J2SE) clients
/src：all Java sources
/webapps：pushlet.war file with the examples; also unpacked in the pushlet
subdir
/doc：all documentation
/lib：the pushlet.jar and pushletclient.jar libraries
/thirdparty：external libraries
2.ajax 使用到的pushlet檔案
ajax-pushlet-client.js
pushlet.properties
sources.properties
pushlet.jar
3.針對指定的對象發送，並能傳遞參數(紅字部分為新增)
3.1.修改ajax-pushlet-client.js
新增參數定義
/**
Namespaced Pushlet functions. */
var PL = {
NV_P_FORMAT: 'p_format=xml-strict',
..........
state: 1,
parameters: new Array(new
Array),//新增參數定義
……………………..
//
Optionally attach session id
if (PL.sessionId != null) {
url = url +
'&p_id=' + PL.sessionId;
if (anEvent ==
'p_leave') {
PL.sessionId
= null;
}
}
// 新增參數加入傳遞
if(PL.parameters.length
> 0) {
for (var i = 0; i <
PL.parameters.length; i++) {
var para = PL.parameters[i];
for(var key in para) {
url += "&" + key + "=" +
para[key];
}
}
}
3.2.修改nl.justobjects.pushlet.core.
Session.java將自訂參數內容加入session讓後續可取得自訂內容
private Event event;
public static Session create(String
anId,Event anEvent) throws PushletException {
Session session;
try {
session =
(Session) onfig.getClass(SESSION_CLASS,"nl.justobjects.pushlet.core.Session").newInstance();
} catch (Throwable t) {
throw new
PushletException("Cannot instantiate Session from config", t);
}
// Init sessionz
session.id = anId;
session.controller
= Controller.create(session);
session.subscriber =
Subscriber.create(session);
session.event = anEvent;
return session;
}
public Event getEvent() {
return event;
}
public void setEvent(Event anEvent) {
event=anEvent;
}
3.3.修改nl.justobjects.pushlet.core.
SessionManager.java 指定對象ID及自訂參數帶入
public Session createSession(Event
anEvent) throws PushletException {
// Trivial
//return
Session.create(createSessionId());
return
Session.create(anEvent.getField("guid",createSessionId()),anEvent);
}
3.4.新增一支servlet程式繼承nl.justobjects.pushlet.servlet.Pushlet.java將指定對象ID及自訂參數帶入
public class PushServlet extends Pushlet {
private static final long
serialVersionUID = 1L;
public PushServlet() {
super();
}
protected void doRequest(Event anEvent,
HttpServletRequest request, HttpServletResponse response) {
// Must have valid event
type.
String eventType =
anEvent.getEventType();
try {
// Get Session:
either by creating (on Join eventType)
// or by id (any
other eventType, since client is supposed to have joined).
Session session
= null;
if
(eventType.startsWith(Protocol.E_JOIN)) {
//
Join request: create new subscriber
session
= SessionManager.getInstance().createSession(anEvent);
String
userAgent = request.getHeader("User-Agent");
if
(userAgent != null) {
userAgent
= userAgent.toLowerCase();
}
else {
userAgent
= "unknown";
}
session.setUserAgent(userAgent);
} else {
//
Must be a request for existing Session
//
Get id
String
id = anEvent.getField(P_ID);
// We
must have an id value
if
(id == null) {
response.sendError(HttpServletResponse.SC_BAD_REQUEST,
"No id specified");
Log.warn("Pushlet:
bad request, no id specified event=" + eventType);
return;
}
// We
have an id: get the session object
session
= SessionManager.getInstance().getSession(id);
session.setEvent(anEvent);
//
Check for invalid id
if
(session == null) {
response.sendError(HttpServletResponse.SC_BAD_REQUEST,
"Invalid or expired id: " + id);
Log.warn("Pushlet: bad request, no session found id=" + id
+ " event=" + eventType);
return;
}
}
Command command
= Command.create(session, anEvent, request, response);
session.getController().doCommand(command);
} catch (Throwable t) {
Log.warn("Pushlet: Exception in doRequest() event=" +
eventType, t);
t.printStackTrace();
response.setStatus(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
}
}
}
4.使用方式
4.1.將ajax-pushlet-client.js，pushlet.properties，sources.properties，pushlet.jar放置對應位置。
例如:Eclipse
ajax-pushlet-client.js à /WebContent/ 網頁置放位置
pushlet.properties，sources.properties à /src/ java原始碼目錄下
pushlet.jar à/WebContent/WEB-INF/lib 專案引用jar目錄下
4.2.修改web.xml
<servlet>
<servlet-name>pushlet</servlet-name>
<servlet-class>新增的servlet路徑PushServlet</servlet-class>
<load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>pushlet</servlet-name>
<url-pattern>/pushlet.srv</url-pattern>
</servlet-mapping>
4.3.利用EventPullSource方式進行開發
public
class CometInfo implements Serializable{
private static final long
serialVersionUID = 1L;
static public class showInfo extends
EventPullSource {
@Override
protected long
getSleepTime() {
return 9000; //多久執行一次，單位毫秒
}
@Override
protected Event pullEvent()
{
Event event = Event.createDataEvent("/event/page");
event.setField("INFO","INFO"
);
return event;
}
}
}
將該程式之class名稱(含完整路徑)加入sources.properties
source1=com.boxmylife.events.box.CometInfo$showInfo
4.4.前端使用方式
將ajax-pushlet-client.js 引用進來
<script type="text/javascript"
src="../js/ajax-pushlet-client.js"></script>
PL.webRoot=
"http://127.0.0.1:8080/site";
PL._init();
PL.parameters.push({"guid":"123456789"});
//傳遞自訂參數，參數guid為指定發送的對象ID
PL.joinListen('/event/page');
function
onData(event) {
var message =
decodeURIComponent(event.get('INFO')); //解決中文亂碼
if(message != null && message !=
"undefined"){
alert(message);
}
}
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