将 bean 数据从 servlet 传递到 jsp 的问题

Question

I have 2 jsp pages, one called as MyPage.jsp and other as View.jsp.我有 2 个 jsp 页面，一个称为 MyPage.jsp，另一个称为 View.jsp。 View.jsp has a tree structure. View.jsp 具有树形结构。 MyPage.jsp has some text fields called as number and design which need to be populated through a bean via servlet. MyPage.jsp 有一些称为数字和设计的文本字段，需要通过 servlet 通过 bean 填充。 On click of any of the tree node in View.jsp, MyPage.jsp should be rendered with the text fields values set.单击 View.jsp 中的任何树节点时，应使用设置的文本字段值呈现 MyPage.jsp。 Now what is happening is since MyPage.jsp is being called twice, ie once in View.jsp(in ajax function) and second in the request dispatcher in the servlet so the bean values being set in the servlet are lost.现在发生的事情是因为 MyPage.jsp 被调用了两次，即一次在 View.jsp 中（在 ajax 函数中），第二次在 servlet 的请求调度程序中，因此在 servlet 中设置的 bean 值丢失了。 Please suggest a better way so as to retain the values throughout and that on click of the tree node MyPagejsp is rendered with the field values set.请提出一种更好的方法，以便在整个过程中保留这些值，并且在单击树节点 MyPagejsp 时会使用设置的字段值呈现。

responseBean.setNumber("220");
responseBean.setDesign("xyz");
response.setContentType("text/html");                        
response.setCharacterEncoding("UTF-8");
request.setAttribute("responseBean", responseBean);
RequestDispatcher requestDispatcher = getServletContext().getRequestDispatcher("/MyPage.jsp");
requestDispatcher.include(request, response);
response.getWriter().write("Success");

The jsp page from where MyPage.jsp is called with the bean values set has following code jsp 页面从其中调用 MyPage.jsp 并设置 bean 值具有以下代码

View.jsp查看.jsp

$.ajax({
 url : AJAX_SERVLET,
type: "GET",
data: "Number="+node.data.title,
success : function(output) {                                
$("[id=content]").attr("src", '/Test-portlet/MyPage.jsp');
}
});
}

MyPage.jsp MyPage.jsp

<jsp:useBean id="responseBean" class="com.web.bean.ResponseBean" scope="request">

<jsp:setProperty name="responseBean" property="*"/>

</jsp:useBean>
<body>
<%System.out.println("Values"+responseBean.getNumber()); %>
</body>

In the above MyPage.jsp code, System.out.println is printing the value twice;在上面的 MyPage.jsp 代码中，System.out.println 打印了两次值； once as Values 202 and second as Values null.一次作为值 202，第二次作为值 null。 Since it replaces the original value with null just because MyPage.jsp is called twice and so the second time value is lost.由于它将原始值替换为 null 只是因为 MyPage.jsp 被调用两次，因此第二次值丢失。 Please help请帮忙

Answer 1

I believe that you're confusing/misunderstanding some basic concepts, particularly how HTTP works and how Ajax is supposed to work.我相信您会混淆/误解一些基本概念，特别是 HTTP 的工作原理以及 Ajax 的工作原理。

What is happening here is that you're effectively firing two HTTP requests.这里发生的是您有效地触发了两个 HTTP 请求。 One by $.ajax() and other by element.attr('src', url) .一个是$.ajax() ，另一个是element.attr('src', url) 。 Each request results in a fully distinct bean instance being created and set.每个请求都会导致创建和设置一个完全不同的 bean 实例。 You're completely ignoring the bean data in the callback of the $.ajax() request.您完全忽略了$.ajax()请求回调中的 bean 数据。 I am not sure what HTML element [id=content] represents, but I guess that it's an <iframe> .我不确定 HTML 元素[id=content]代表什么，但我猜它是一个<iframe> 。 That's not entirely the right way.这并不完全正确。

You should end up with effectively firing one HTTP request.您最终应该会有效地触发一个 HTTP 请求。 There are basically 2 solutions:基本上有2个解决方案：

Forget the $.ajax() and send the request by element.attr('src', url) .忘记$.ajax()并通过element.attr('src', url)发送请求。
```
 $("[id=content]").attr("src", "/Test-portlet/MyPage.jsp?number=" + encodeURIComponent(node.data.title));
```
You can also change the URL to be a servlet one so that you have a bit more preprocessing control and finally use RequestDispatcher#forward() instead of include() .您还可以将 URL 更改为一个 servlet，以便您有更多的预处理控制，最后使用RequestDispatcher#forward()而不是include() 。 Do NOT write HTML to the response in the servlet.不要将 HTML 写入 servlet 中的响应。 Let JSP do it.让 JSP 来做吧。
Forget the <iframe> thing and process the response fully by Servlet/Ajax without intervention of JSP.忘记<iframe>的事情并完全通过 Servlet/Ajax 处理响应，而无需 JSP 的干预。 You would need to convert the bean into other data format which is easily parseable by JavaScript/jQuery.您需要将 bean 转换为其他数据格式，以便通过 JavaScript/jQuery 轻松解析。 I would suggest to use JSON for this.我建议为此使用 JSON 。
```
 $.get(AJAX_SERVLET, { "number": node.data.title }, function(response) { $("#number").text(response.number); $("#design").text(response.design); });
```
with in HTML for example例如在 HTML
```
 <div id="number"></div> <div id="design"></div>
```
and in servlet并在 servlet
```
 //... (create ResponseBean the way as you want) String json = new Gson().toJson(responseBean); response.setContentType("application/json"); response.setCharacterEncoding("UTF-8"); response.getWriter().write(json);
```

将 bean 数据从 servlet 传递到 jsp 的问题

问题描述

1 个解决方案

解决方案1
1 已采纳 2011-07-19 09:32:05

See also:也可以看看：

将 bean 数据从 servlet 传递到 jsp 的问题

问题描述

1 个解决方案

解决方案1 1 已采纳 2011-07-19 09:32:05

See also:也可以看看：

解决方案1
1 已采纳 2011-07-19 09:32:05