打开标签的数量限制

Restriction on number of opened tabs(打开标签的数量限制)

本文介绍了打开标签的数量限制的处理方法,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

网页上有一些链接.

右键单击有在新选项卡中打开链接"选项(浏览器选项).

On right click there is option of 'open link in new tab'(browser option).

我想限制用户不要打开两个以上的标签?我该怎么做?

I want to restrict user for not opening more that two tabs? How can i do this?

<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
<ul>
<li><a href="http://localhost:8080/struts_tab/abcForm1.action" oncontextmenu="return false;"><span>First Click[Right Click disabled]</span></a></li>
<li><a href="http://localhost:8080/struts_tab/defForm2.action"><span>Second clieck[Not more than 2 tabs]</span></a></li>
</ul>
</body>
</html>

推荐答案

您不能限制用户打开新标签页.
(这让我想起了没有按钮,没有地址栏,但仍然响应退格和其他事件的旧弹出窗口)

You can't restrict the user from opening a new tab.
(This reminds me the old pop-ups with no buttons, no address bar, but still responding to backspace and other events)

但是,您可以让您的应用识别打开第三个标签页的尝试,并加载不同的结果(例如错误消息),例如:

You can however make your app recognize the attempt of opening a third tab, and load a different result like an error message, for example:

已达到最大打开标签限制.请同时使用不超过两个选项卡.关闭此标签

Maximum open tabs limit reached. Please use no more than two tabs concurrently. close this tab

为此,您可以使用 HTML5 sessionStorage.
注意:Web 存储(sessionStoragelocalStorage)现在所有浏览器都支持.

To do this, you can use HTML5 sessionStorage.
Note: Web Storage (sessionStorage and localStorage) is supported on every browser nowadays.

这是一个全局对象(sessionStorage),维护一个存储区域在页面会话期间可用.页面会话只要浏览器打开并在页面上存活,就会持续重新加载和恢复.在新标签页或窗口中打开页面会导致将启动一个新会话.

sessionStorage

This is a global object (sessionStorage) that maintains a storage area that's available for the duration of the page session. A page session lasts for as long as the browser is open and survives over page reloads and restores. Opening a page in a new tab or window will cause a new session to be initiated.

那你就可以了

  • 如果sessionStorage中不存在,在JSP中生成一个唯一的token,放到sessionStorage中,

  • if not present in sessionStorage, generate an unique token in JSP, and put it in sessionStorage,

$(function(){
    // Read the ID. If it's null, this is a new tab: 
    // generate the ID and store it for later.
    var tabId = sessionStorage.getItem("tabId");
    if (tabId == null){
        tabId = Math.random();
        sessionStorage.putItem("tabId",tabId);
    }

  • 将其发送回操作

  • send it back to the action

        // Add the ID to the form (as hidden field), 
        // so it will be posted back in next submission.
        $('<input>').attr('type'  , 'hidden')
                    .attr('name'  , 'tabId')
                    .attr('value' , tabId)
        .appendTo('form');
    });
    

    ,可能是 BaseAction 中的 setter,由其他操作扩展,并由 prepare() 读取,或者 在拦截器中更好

    , maybe to a setter in a BaseAction, extendend by the other actions, and read by prepare(), or much better in an Interceptor;

    把它放在一个集合中,检查它是否已经包含两个元素,否则返回错误结果,应该全局映射:

    put it in a collection checking that it doesn't contain already two elements, otherwise return the error result, that should be mapped globally:

    public String intercept(ActionInvocation actionInvocation) throws Exception {
        Action action = (Action) actionInvocation.getAction();
        if(action instanceof LimitedTabsAware){ //interface to identify special actions
            ActionContext context = actionInvocation.getInvocationContext();
            Map<String, String[]> request = ((HttpServletRequest) 
                                context.get(StrutsStatics.HTTP_REQUEST)).getParameterMap();
    
            if (request.containsKey("tabId")){              
                String tabId = (String) request.get("tabId")[0];
                List<String> openTabs = context.getSession().get("OPEN_TABS_KEY");
    
                if (openTabs.contains(tabId)){
                    return actionInvocation.invoke();                   
                } else if (openTabs.size()>=2){
                    return "tabLimitExceeded"; // global result
                } else {
                    openTabs.add(tabId);
                    context.getSession().put("OPEN_TABS_KEY", openTabs);
                    return actionInvocation.invoke();
                }
    
            } else {
                throw new IllegalArgumentException("There is no tabId in this request.");
            }
        } else {
            return actionInvocation.invoke();
        }
    }
    

  • 然后您应该找到一种方法来识别选项卡何时关闭(以释放一个插槽),方法是:

    Then you should find a way to recognize when a tab get closed (to free one slot), by either:

    • 优化集合中元素的有效期(如果您有一段时间不使用标签,会话过期,所以必须做集合中的令牌)
    • 否则,在您的页面中放置一个 javascript AJAX 计时器(例如,每 30 秒),发送一个 keep-alive 向动作发出信号以刷新元素的有效性.如果选项卡关闭,则不再发送信号.
    • timizing the period of validity of the elements in your collection (if you don't use a tab for some time, the session expires, and so must do the token in the collection)
    • otherwise, putting a javascript AJAX timer in your page (eg. every 30 seconds), that send a keep-alive signal to an action to refresh the validity of the element. If the tab get closed, the signal is not sent anymore.

    这篇关于打开标签的数量限制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编程学习网!

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