了解Spring MVC的DeferredResult类弹簧MVC-GitHub的聊天应用程序上下文 [英] Understanding the Spring MVC's DeferredResult class in the context of the spring-mvc-chat github application
本文介绍了了解Spring MVC的DeferredResult类弹簧MVC-GitHub的聊天应用程序上下文的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我想更好地理解下面的Spring MVC 3.2应用程序是如何工作的：<一href=\"https://github.com/rstoyanchev/spring-mvc-chat\">https://github.com/rstoyanchev/spring-mvc-chat
我的问题是关于<一个href=\"http://static.springsource.org/spring/docs/3.2.x/javadoc-api/org/springframework/web/context/request/async/DeferredResult.html\">deferredResult Spring MVC的类。我注意到，在给定的时间，因为有连接到聊天应用程序的用户中有 chatRequests 地图尽可能多的条目。
说，有 3的用户连接以聊天应用。你会看到，当用户＃3发布消息（参见下面的postMessage方法），然后点击 for循环（在postMessage的方法）迭代三次。我想不通这是为什么。
我包括下面的示例code。
code的控制器：
@Controller
@RequestMapping（/ MVC /聊天）
公共类ChatController { 私人最终ChatRepository chatRepository;
私人最终地图＆LT; DeferredResult＆LT;名单，LT;弦乐＆GT;＆gt;中整数GT; chatRequests =新的ConcurrentHashMap＆LT; DeferredResult＆LT;名单，LT;弦乐＆GT;＆gt;中整数GT;（）; @Autowired
公共ChatController（ChatRepository chatRepository）{
this.chatRepository = chatRepository;
} @RequestMapping（方法= RequestMethod.GET）
@ResponseBody
公共DeferredResult＆LT;名单，LT;弦乐＆GT;＆GT;的getMessages（@RequestParam INT messageIndex）{ 最后DeferredResult＆LT;名单，LT;弦乐＆GT;＆GT; deferredResult =新DeferredResult＆LT;名单，LT;弦乐＆GT;＆GT;（NULL，Collections.emptyList（））;
this.chatRequests.put（deferredResult，messageIndex）; deferredResult.onCompletion（新的Runnable（）{
@覆盖
公共无效的run（）{
chatRequests.remove（deferredResult）;
}
}）; 清单＆LT;串GT;消息= this.chatRepository.getMessages（messageIndex）;
如果（！messages.isEmpty（））{
deferredResult.setResult（消息）;
} 返回deferredResult;
} @RequestMapping（方法= RequestMethod.POST）
@ResponseBody
公共无效的postMessage（@RequestParam字符串消息）{ this.chatRepository.addMessage（消息）; //更新所有的聊天请求作为POST请求的一部分
//见的Redis分支的一个更复杂的，无阻塞的方法 对于（进入＆LT; DeferredResult＆LT;名单，LT;弦乐＆GT;＆gt;中整数GT;项：this.chatRequests.entrySet（））{
清单＆LT;串GT;消息= this.chatRepository.getMessages（entry.getValue（））;
entry.getKey（）的setResult（消息）。
}
}
}
的Javascript code：
$（文件）。就绪（函数（）{ 功能ChatViewModel（）{ VAR认为这=; that.userName = ko.observable（''）;
that.chatContent = ko.observable（''）;
that.message = ko.observable（''）;
that.messageIndex = ko.observable（0）;
that.activePollingXhr = ko.observable（NULL）;
VAR keepPolling = FALSE; that.joinChat =功能（）{
如果（that.userName（）。修剪（）！=''）{
keepPolling = TRUE;
pollForMessages（）;
}
} 功能pollForMessages（）{
如果（！keepPolling）{
返回;
}
变种形式= $（＃joinChatForm）;
that.activePollingXhr（$阿贾克斯（网址：{url：form.attr（行动），键入：GET，数据：form.serialize（），缓存：假的，
成功：函数（消息）{
的console.log（消息）;
对于（VAR I = 0; I＆LT; messages.length;我++）{
that.chatContent（that.chatContent（）+信息[I] +\\ n）;
that.messageIndex（that.messageIndex（）+ 1）;
}
}，
错误：功能（XHR）{
如果（xhr.statusText =中止和放大器;！＆安培;！xhr.status = 503）{
resetUI（）;
console.error（无法获取聊天消息聊天结束了。）;
}
}，
完成：pollForMessages
}））;
$（'＃消息）专注（）。
} that.postMessage =功能（）{
如果（that.message（）。修剪（）！=''）{
变种形式= $（＃postMessageForm）;
$阿贾克斯（网址：{url：form.attr（行动），键入：POST，
数据：消息= [+ that.userName（）+]+ $（＃postMessageForm输入[名称=消息]）VAL（）。
错误：功能（XHR）{
console.error（错误发布聊天消息：状态=+ xhr.status +，状态文本=+ xhr.statusText）;
}
}）;
that.message（''）;
}
} that.leaveChat =功能（）{
that.activePollingXhr（NULL）;
resetUI（）;
this.userName（''）;
} 功能resetUI（）{
keepPolling = FALSE;
that.activePollingXhr（NULL）;
that.message（''）;
that.messageIndex（0）;
that.chatContent（''）;
} } //激活knockout.js
ko.applyBindings（新ChatViewModel（））;}）;
和html页面：
＆LT;！DOCTYPE HTML＆GT;
＆LT; HTML的xmlns =http://www.w3.org/1999/xhtml的xmlns：TH =http://www.thymeleaf.org＆GT;
＆LT; HEAD＆GT;
＆LT;标题＆GT;聊天和LT; /标题＆GT;
＆LT; META HTTP-EQUIV =Content-Type的CONTENT =text / html的;字符集= UTF-8/＆GT;
＆LT; /头＆GT;
＆LT;身体GT;
＆LT; H1＆GT;聊天和LT; / H1＆GT; ＆LT;表ID =joinChatForm日：行动=@ {/ MVC /聊天}数据绑定=可见：activePollingXhr（）== NULL＆GT;
＆所述p为H.;
＆LT;标签=用户＆gt;用户：LT; /标签＆gt;
＆LT;输入ID =用户NAME =用户类型=文本数据绑定=值：用户名/＆GT;
＆LT;输入名称=messageIndex类型=隐藏数据绑定=值：messageIndex/＆GT;
＆LT;按钮ID =启动类型=提交数据绑定=点击：joinChat＆GT;加入聊天＆LT; /按钮＆GT;
＆所述; / P＆GT;
＆LT; /表及GT; ＆LT;表ID =leaveChatForm日：行动=@ {/ MVC /聊天}数据绑定=可见：activePollingXhr（）！= NULL＆GT;
＆所述p为H.;
你聊天为＆lt;强大的数据绑定=TEXT：用户名＆GT;＆LT; / STRONG＆GT;
＆LT;按钮ID =离开类型=提交数据绑定=点击：leaveChat＆GT;保留聊天＆LT; /按钮＆GT;
＆所述; / P＆GT;
＆LT; /表及GT; ＆LT; DIV数据绑定=看得见！activePollingXhr（）= NULL＆GT;
＆LT; textarea的行数=15COLS =60只读=只读数据绑定=TEXT：chatContent＆GT;＆LT; / textarea的＆GT;
＆LT; / DIV＆GT; ＆LT;表ID =postMessageForm日：行动=@ {/ MVC /聊天}数据绑定=可见：activePollingXhr（）！= NULL＆GT;
＆所述p为H.;
＆LT;输入ID =消息NAME =消息类型=文本数据绑定=值：消息/＆GT;
＆LT;按钮ID =POST类型=提交数据绑定=点击：postMessage的＆GT;邮政和LT; /按钮＆GT;
＆所述; / P＆GT;
＆LT; /表及GT;
＆LT; /身体GT;
＆LT;脚本类型=文/ JavaScript的SRC =../../../资源/ JS / jQuery的-1.7.2.min.js号：SRC =@ {/资源/ JS / jquery- 1.7.2.min.js}＆GT;＆LT; / SCRIPT＆GT;
＆LT;脚本类型=文/ JavaScript的SRC =../../../资源/ JS /淘汰赛2.0.0.js号：SRC =@ {/资源/ JS /淘汰赛2.0。 0.js}＆GT;＆LT; / SCRIPT＆GT;
＆LT;脚本类型=文/ JavaScript的SRC =../../../资源/ JS / chat.js日：SRC =@ {/资源/ JS / chat.js}＆GT;＆LT ; / SCRIPT＆GT;＆LT; / HTML＆GT;
解决方案
我在使用Spring的DeferredResult类的作者详细讨论这个话题，这里是我们谈话的相关部分：
要引用罗森Stoyanchev：
粗略地说。一个DeferredResult是一个开放的要求有关。
当请求完成后，DeferredResult从除去
图，然后，客户端发出一个新的长轮询请求，这
增加了一个新的实例DeferredResultI am trying to better understand how the following spring mvc 3.2 application works: https://github.com/rstoyanchev/spring-mvc-chat
My question is about the deferredResult Spring MVC class. I noticed that at a given time there are as many entries in the
chatRequestsMap as there are users connected to the chat application.Say there are 3 users connected to the chat application. You will see that when user #3 posts a message (see postMessage method below), then the for loop (in postMessage method) iterates three times. I can't figure out why that is.
I am including sample code below.
Code for controller:
@Controller @RequestMapping("/mvc/chat") public class ChatController { private final ChatRepository chatRepository; private final Map<DeferredResult<List<String>>, Integer> chatRequests = new ConcurrentHashMap<DeferredResult<List<String>>, Integer>(); @Autowired public ChatController(ChatRepository chatRepository) { this.chatRepository = chatRepository; } @RequestMapping(method = RequestMethod.GET) @ResponseBody public DeferredResult<List<String>> getMessages(@RequestParam int messageIndex) { final DeferredResult<List<String>> deferredResult = new DeferredResult<List<String>>(null, Collections.emptyList()); this.chatRequests.put(deferredResult, messageIndex); deferredResult.onCompletion(new Runnable() { @Override public void run() { chatRequests.remove(deferredResult); } }); List<String> messages = this.chatRepository.getMessages(messageIndex); if (!messages.isEmpty()) { deferredResult.setResult(messages); } return deferredResult; } @RequestMapping(method = RequestMethod.POST) @ResponseBody public void postMessage(@RequestParam String message) { this.chatRepository.addMessage(message); // Update all chat requests as part of the POST request // See Redis branch for a more sophisticated, non-blocking approach for (Entry<DeferredResult<List<String>>, Integer> entry : this.chatRequests.entrySet()) { List<String> messages = this.chatRepository.getMessages(entry.getValue()); entry.getKey().setResult(messages); } } }Javascript code:
$(document).ready(function() { function ChatViewModel() { var that = this; that.userName = ko.observable(''); that.chatContent = ko.observable(''); that.message = ko.observable(''); that.messageIndex = ko.observable(0); that.activePollingXhr = ko.observable(null); var keepPolling = false; that.joinChat = function() { if (that.userName().trim() != '') { keepPolling = true; pollForMessages(); } } function pollForMessages() { if (!keepPolling) { return; } var form = $("#joinChatForm"); that.activePollingXhr($.ajax({url: form.attr("action"), type: "GET", data: form.serialize(), cache: false, success: function(messages) { console.log(messages); for (var i = 0; i < messages.length; i++) { that.chatContent(that.chatContent() + messages[i] + "\n"); that.messageIndex(that.messageIndex() + 1); } }, error: function(xhr) { if (xhr.statusText != "abort" && xhr.status != 503) { resetUI(); console.error("Unable to retrieve chat messages. Chat ended."); } }, complete: pollForMessages })); $('#message').focus(); } that.postMessage = function() { if (that.message().trim() != '') { var form = $("#postMessageForm"); $.ajax({url: form.attr("action"), type: "POST", data: "message=[" + that.userName() + "] " + $("#postMessageForm input[name=message]").val(), error: function(xhr) { console.error("Error posting chat message: status=" + xhr.status + ", statusText=" + xhr.statusText); } }); that.message(''); } } that.leaveChat = function() { that.activePollingXhr(null); resetUI(); this.userName(''); } function resetUI() { keepPolling = false; that.activePollingXhr(null); that.message(''); that.messageIndex(0); that.chatContent(''); } } //Activate knockout.js ko.applyBindings(new ChatViewModel()); });and html page:
<!DOCTYPE html> <html xmlns="http://www.w3.org/1999/xhtml" xmlns:th="http://www.thymeleaf.org"> <head> <title>Chat</title> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /> </head> <body> <h1>Chat</h1> <form id="joinChatForm" th:action="@{/mvc/chat}" data-bind="visible: activePollingXhr() == null"> <p> <label for="user">User: </label> <input id="user" name="user" type="text" data-bind="value: userName"/> <input name="messageIndex" type="hidden" data-bind="value: messageIndex"/> <button id="start" type="submit" data-bind="click: joinChat">Join Chat</button> </p> </form> <form id="leaveChatForm" th:action="@{/mvc/chat}" data-bind="visible: activePollingXhr() != null"> <p> You're chatting as <strong data-bind="text: userName"></strong> <button id="leave" type="submit" data-bind="click: leaveChat">Leave Chat</button> </p> </form> <div data-bind="visible: activePollingXhr() != null"> <textarea rows="15" cols="60" readonly="readonly" data-bind="text: chatContent"></textarea> </div> <form id="postMessageForm" th:action="@{/mvc/chat}" data-bind="visible: activePollingXhr() != null"> <p> <input id="message" name="message" type="text" data-bind="value: message" /> <button id="post" type="submit" data-bind="click: postMessage">Post</button> </p> </form> </body> <script type="text/javascript" src="../../../resources/js/jquery-1.7.2.min.js" th:src="@{/resources/js/jquery-1.7.2.min.js}"></script> <script type="text/javascript" src="../../../resources/js/knockout-2.0.0.js" th:src="@{/resources/js/knockout-2.0.0.js}"></script> <script type="text/javascript" src="../../../resources/js/chat.js" th:src="@{/resources/js/chat.js}"></script> </html>
解决方案I discussed this topic at length with the author of Spring's DeferredResult class and here is the relevant part of our conversation:
To quote Rossen Stoyanchev:
Roughly speaking. A DeferredResult is associated with an open request. When the request completes, the DeferredResult is removed from the map, and then, the client issues a new long polling request, which adds a new DeferredResult instance
这篇关于了解Spring MVC的DeferredResult类弹簧MVC-GitHub的聊天应用程序上下文的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
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