页面之间传递值，mvc参数问题（前后台）

页面之间传递值===============

用内置对象request以一个页面
<%request.setAttribute("txt", "生活服务") %>
第二个页面
<%String txt = request.getAttribute("txt") %>（属性）
<th><%=txt %></th>

也可以吧一个页面的“生活服务”作为参数（?txt=生活服务）传到第二个页面，用<%request.getParameter("txt") %>获取就行了（参数）

这种就是相当于在值栈中，也可直接用<input type="hidden" name="roleid" id="roleid" value="${id}">

var roleId=$("#roleid").val();//这样就实现了jsp--js//隐藏域


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model中add的，跳转时传的参数是，传给后面要跳转的页面，在mvc中注解表明的往往是要跳转的页面，标签下面的方法参数是前面请求这个页面的参数，方法体是处理这些参数后返回给注解的参数，隐藏域，就是在跳转之前用？或model.set传入，然后注解页面用隐藏域获取，之后js获取
向即将跳转页面传值
return "redirect:index.do?szie=1";
model.addAttribute(“szie”，szie);，index接收到size后跳转前modeladd才可到值栈中，被index直接用jstl表达式用


model.addObject("parentMenus", parentMenus);   ///////////////////////////////////////////////////////////////一个key,对应对个value

不用回调用值栈， 用model.addAttribute   此时jsp用此
<%--  <c:choose>
                        <c:when test="${roledetl.status==1}">
                        <input class="width_240" name="status"   value=" 有效" />
                        </c:when>
                         <c:when test="${roledetl.status==0}">
                        <input class="width_240" name="status"   value=" 无效" />
                        </c:when>
                       </c:choose> --%>
                      <%--  <c:if test="${roledetl.status==1}">
                       <input class="width_240" name="status"   value=" 有效" />
                       </c:if> --%>
                        <select name="status" class="width_240">
                                <option value="1" <c:if test="${roledetl.status==1}">selected="selected"</c:if>>有效</option>
                                <option value="0" <c:if test="${roledetl.status==2}">selected="selected"</c:if>>无效</option>
                         </select>
                         <select name="status" class="width_240">
                                <option value="0" selected="selected">===请先选择===</option>
                                <c:forEach items="${item}" var="item" >
                                <option value="${item.id }" selected="selected">${item.name }</option>
                                </c:forEach>
                         </select>

不用回调用值栈， 用model.addAttribute前台用jstl表达式




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<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<%@ taglib prefix="fn" uri="http://java.sun.com/jsp/jstl/functions" %>
<%@ taglib uri="http://www.springframework.org/tags/form" prefix="form" %>



<td><select name="org" class="width_240">
                                <option value="0" selected="selected">===请先选择===</option>
                                <c:forEach items="${orgs}" var="item" >
                                <option value="${item.id }" >${item.orgName }</option>
                                </c:forEach>
                         </select>
                         </td>

@RequestMapping(value = "/edit")
    public void edit(Long id,Model model) {

        if (id != null) {
        User roledetl = userService.getUserForEditById(id);
            model.addAttribute("roledetl", roledetl);
           List<Organization> orgs=  organizationService.getOrganization();
            model.addAttribute("orgs", orgs);
//            model.addAttribute("areas", acountService.getDictDataListByTypeCodeAndParentId(StaticUtil.PROVINCE_CITY, organization.getCityId()));
        }
//        model.addAttribute("provinces", acountService.getDictDataListByTypeCode(StaticUtil.PROVINCE_CITY));
//        model.addAttribute("roledetl",null);
    }










        ===================================
方法二    model.addObject("parentMenus", parentMenus);   ///////////////////////////////////////////////////////////////一个key,对应对个value
<c:forEach items="${parentMenus}" var="parent">
        <c:choose>
            <c:when test="${parent.isleaf=='0'}">
                <div class="titleArea_normal" ><i class="icon_spgl"></i>${parent.menuName}</div>
                <div class="box3" style="display: none">
                    <c:forEach items="${parent.childs}" var="item">
                        <c:choose>
                            <c:when test="${!empty item.url}">
                                <a class="list" href="${pageContext.request.contextPath}${item.url}" target="mainFrame"><span>${item.menuName}</span></a>
                            </c:when>
                            <c:otherwise>
                                <a   class="list" href="javascript:void(0)" target="mainFrame"><span>${item.menuName}</span></a>
                            </c:otherwise>
                        </c:choose>
                    </c:forEach>
                </div>

            </c:when>
            <c:when test="${parent.isleaf=='1'}">
                <a class="titleArea_normal  firstShow"  href="${pageContext.request.contextPath}${parent.url }" target="mainFrame"><i class="icon_home1"></i>${parent.menuName}<input type="hidden"/></a>
            </c:when>
        </c:choose>
    </c:forEach>
  
方法三 直接用@ResponseBody  结合ajax
  
  
隐藏域

页面a  var roles = "<a name='showMenu' href='${pageContext.request.contextPath}/system/users/userroles.do?id=" + lineData["id"] + "'  class='cyan'>【授用户组】</a>";

  String id = request.getParameter("id");
<%=id %>

隐藏域
@RequestMapping(value = "/userroles")
    public void checkbox( @RequestParam Long id ,Model model ) {
    model.addAttribute("id", id);

    }
<div>
<input id="userId" type="hidden" value="${id }">
</div>