使用JSTL将新参数添加到当前URL [英] Adding new parameter to current URL using JSTL

问题描述

我的应用程序允许用户在任何给定时刻更改语言，这给我带来了一些麻烦.例如，如果用户通过URL指定页面:/category/8?page=3，然后尝试通过?language=en更改语言，它将删除先前的参数并将其带到第一页.

My application allows user to change language in any given moment and that cause me some trouble. For example if user specify page by URL: /category/8?page=3 and then would try to change the language by ?language=en it will erase previous parameters and take him to first page.

如何获取当前URL并向其添加另一个参数?我想实现以下目标:/category/8?page=3&language=en，当当前的ULR为/category/8?page=3，并且用户尝试更改语言时.

How can I get a current URL and add another parameter to it? I'd like to achieve something like this: /category/8?page=3&language=en when current ULR is /category/8?page=3 and user tried to change a language.

我尝试使用${pageContext.request.requestURL}，但这不是我想要的，因为它返回了jsp页面.

I tried using ${pageContext.request.requestURL} but that's not what I look for as it returns jsp page.

推荐答案

这是我使用的标记文件.将其另存为/WEB-INF/tags/replaceParam.tag:

Here's a tag file I use. Save it as /WEB-INF/tags/replaceParam.tag:

<%@ tag pageEncoding="UTF-8" trimDirectiveWhitespaces="true" %>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<%@ attribute name="name" required="true" type="java.lang.String" %>
<%@ attribute name="value" required="true" type="java.lang.String" %>

<c:url value="">

    <%-- 
      replaces or adds a param to a URL
      if $name in query then replace its value with $value. 
      copies existing 
    --%>

    <c:forEach items="${paramValues}" var="p">
        <c:choose>
            <c:when test="${p.key == name}">
                <c:param name="${name}" value="${value}"/>
            </c:when>
            <c:otherwise>
                <c:forEach items="${p.value}" var="val">
                    <c:param name="${p.key}" value="${val}"/>
                </c:forEach>
            </c:otherwise>
        </c:choose>
    </c:forEach>

    <%-- if $name not in query, then add --%>
    <c:if test="${empty param[name] }">
        <c:param name="${name}" value="${value}"/>
    </c:if>

</c:url>

在其他页面中使用(例如url为/category/9?page=3):

Usage in another page (ex url is /category/9?page=3):

<%@ taglib prefix="my" tagdir="/WEB-INF/tags" %>

<my:replaceParam name='language' value='en' />

输出为/category/8?page=3&language=en

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