在 jsp 中获取 Hashmap

Question

public class DBConnection {
public HashMap<Object, List<Dashboard>>  getStoreResult() {
    ArrayList<Dashboard> dashRec=new ArrayList<Dashboard>();
    try{
        Class.forName("");
        Connection con=DriverManager.getConnection("");
        Statement st=con.createStatement();
        ResultSet rs=st.executeQuery("");
        HashMap<Object, List<Dashboard>> map = new HashMap<>();
        while (rs.next()) {
            }
         return map;

小服务程序代码：

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        HashMap<Object, List<Dashboard>> map = new DBConnection().getStoreResult();
        request.setAttribute("map",map);
        RequestDispatcher rd=request.getRequestDispatcher("Dashboard.jsp");  
        rd.forward(request, response);

JSP 代码：

%@ page language="java" contentType="text/html; charset=ISO-8859-1"
    pageEncoding="ISO-8859-1"%>

<%@ page import ="java.util.*"%>
<%@ page import="com.org.myprj.Dashboard" %>  
<% Map<Object, List<Dashboard>> map = (HashMap<>)request.getAttribute("map");%>

I have created Hashmap with key as object and value as Arraylist.Till servlet,it works fine.I want it in jsp page.How to get this Hashmap in jsp page?

Answer 1

使用 JSTL 库并迭代 map，如下所示：

<c:forEach var="vmap" items="${map}">
    Key is ${vmap.key} and  Value is ${vmap.value}<br>
</c:forEach>

如果不能使用 JSTL 库，可以访问并迭代如下：

<% Map<Object, List<Dashboard>> map = (Map<Object, List<Dashboard>>)request.getAttribute("map");%>

然后像往常在 Java 中一样迭代map 。