在jsp里面的javascript中访问会话变量 [英] accessing session variables in javascript inside jsp

问题描述

我需要为google API表提供数据...所以我将它从servlet发送到JSP

I need to provide data for google APIs table... so I'll send it from servlet to JSP

但是如何在googles中访问这些数据javascript？

but how can I access this data in "googles" javascript?

我将提供另一个JS的样本 - 非常简单 - 只是为了让我学习如何制作主题

I'll provide sample of another JS - very simple one - just to let me learn how to make what topic says

    <script>
        function showTable()
        {
            <%
                Object obj = session.getAttribute("list");
                List<String> list = new ArrayList<String>();
                int size = 0; 

                if (obj != null) {
                    list = (ArrayList<String>) obj;
                    size = (Integer) session.getAttribute("size");
                }

                for (int i = 0 ; i < size ; i++) {
                    String value = list.get(i);

            %>
                    alert('<%= i %> = <%= value %> ');
            <%
                }

            %>                
        }
    </script>

它必须打印给定列表的元素......但是现在它只是一个内部警报的大字体它...重构它？我不喜欢在JSP中使用很多java，因为servlet应放在它的位置

It has to print elements of given list... but now it's just a big scriplet with alert inside of it... for to refactor it? I don't like having to much java in JSPs, because servlet is where it should be placed

编辑：只是为了总结 - 我更喜欢普通的JS这里循环...一般我更喜欢最小化java代码，并最大化JS

just to sum up - I would prefer "normal" JS for loop here... Generally I'd prefer to minimize java code, and maximize JS

推荐答案

将其转换为 doGet（）中的http://www.hunlock.com/blogs/Mastering_JSON_%28_JavaScript_Object_Notation_%29\"rel =noreferrer> JSON servlet的。您可以使用 Google Gson 进行此操作。假设您有一个列表< Person> ：

Convert it to JSON in doGet() of a preprocessing servlet. You can use among others Google Gson for this. Assuming that you've a List<Person>:

List<Person> persons = createItSomehow();
String personsJson = new Gson().toJson(persons);
request.setAttribute("personsJson", personsJson);
request.getRequestDispatcher("/WEB-INF/persons.jsp").forward(request, response);

（请注意，我将其设为请求属性而非会话属性，您可以免费使用改变它，但我认为它不一定需要是会话属性，因为它不代表会话范围的数据）

将它分配给JS JSP中的变量如下：

Assign it to a JS variable in JSP as follows:

<script>
    var persons = ${personsJson};
    // ...
</script>

这种方式可以作为一个完整的JS对象使用。您可以直接将其提供给Google API。

This way it's available as a fullworthy JS object. You could feed it straight to the Google API.

现在调用servlet的URL而不是JSP。例如，当它映射到 / persons 的URL模式时，通过 http：// localhost：8080 / contextname / persons 。

Now invoke the URL of the servlet instead of the JSP. For example, when it's mapped on an URL pattern of /persons, invoke it by http://localhost:8080/contextname/persons.

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