java - 无法在java中使用jsp变量

Question

我们想要从同一文件中的 java 类内的 jsp 访问变量。有人可以建议如何使用它吗？

下面是代码。在这里，我们在 jsp 标签中使用 data 变量，并且我们想要访问 java 的 DummyDB 类中 data 的值。

JSP 文件:

<%@page import="java.util.ArrayList"%>
<%@page import="java.util.List"%>
<%@page import="java.util.StringTokenizer"%>
<%@ page import="java.sql.*" %>
    <%@ page import="java.io.*"%>
    <%@ page import="java.util.*"%>
    <%@ page import="java.net.*" %>

<%

HttpSession Session = request.getSession(true);

String data = Session.getAttribute("data").toString();

%>

<%!

public class DummyDB {
    private int totalCountries;

   RequestDispatcher rd = request.getRequestDispatcher("include.jsp");
rd.include(request, response); 

    private List<String> countries;
    public DummyDB() {
        countries = new ArrayList<String>();
        StringTokenizer st = new StringTokenizer(data, ",");

        while(st.hasMoreTokens()) {
            countries.add(st.nextToken().trim());
        }
        totalCountries = countries.size();
    }

    public List<String> getData(String query) {
        String country = null;
        query = query.toLowerCase();
        List<String> matched = new ArrayList<String>();
        for(int i=0; i<totalCountries; i++) {

            country = countries.get(i).toLowerCase();
            if(country.startsWith(query)) {
                matched.add(countries.get(i));
            }
        }
        return matched;
    }
        }
%>

Answer 1

更改此:

StringTokenizer st = new StringTokenizer(data, ",");

至:

StringTokenizer st = new StringTokenizer(request.getSession().getAttribute("data"), ",");

如果有效，您可以完全删除此行:

String data = Session.getAttribute("data").toString();