如何從post servlet接收信息以放入HTML/JSP

Question

基本上，我正在處理的這個頁面的目標是讓用戶輸入股票代碼，並將此信息發送到post方法並將數據發送回放在相同的html/jsp頁面上。我已經能夠在表單導向另一個JSP頁面的情況下工作，但這必須是一個單獨的頁面，我希望能夠保持在同一頁面上並讓信息出現。如果你有一個資源可以教我如何處理這個問題，那麼我會很感激，就像解決方案一樣。我一直在使用Gradle構建工具。

這裏是（在index.jsp中）的形式爲：

<h1>Search Stock</h1> 
     <form method="POST" action="DataPage.jsp"> 
       <input type = "text" name = "Symbol"> 
       <input type = "submit" name = "getData"> 
     </form> 

這裏是起作用JSP代碼（DataPage.jsp）：

<% 
    String Ticker = request.getParameter("Symbol"); 
    PrintWriter write = response.getWriter(); 
    if((Ticker == null)){ 
    String message = "Please enter a stock symbol"; 
    write.println(message); 

    }else{ 
    try{ 
     Company object = Serializing.getCompany(Ticker); 
     object.updateData(); 
     write.println("data last added" + object.getLastUpdate()); 
     write.println(object.getSentiment()); 
    }catch(NullPointerException x){ 
     Company object = Serializing.getCompany(Ticker); 
    } 


    }%> 

這裏是我試圖寫的servlet（DataServlet .java），我幾乎沒有使用servlets的經驗，我從不同的來源和關於計算器的問題找到了這個問題：

package Default; 

import javax.servlet.ServletException; 
import javax.servlet.http.HttpServletRequest; 
import javax.servlet.http.HttpServletResponse; 
import java.io.IOException; 
import java.io.PrintWriter; 

/** 
* Created by Ceyer on 9/3/2015. 
*/ 

@javax.servlet.annotation.WebServlet(name = "DataServlet", urlPatterns = ("/")) 
public class DataServlet extends javax.servlet.http.HttpServlet { 

    private static final long serialVersionUID = 1L; 

    public DataServlet() { 
     super(); 

    } 
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { 

    } 
    protected void doPost(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response) throws javax.servlet.ServletException, IOException { 
     String Ticker = request.getParameter("Symbol"); 
     if ((Ticker == null)||Ticker.trim().isEmpty()) { 
      String message = "Please enter a stock symbol"; 
      request.setAttribute("data", message); 
      getServletContext().getRequestDispatcher("/login.jsp").forward(request, response); 
     } else { 

      PrintWriter write = response.getWriter(); 
      try { 
       Company object = Serializing.getCompany(Ticker); 
       object.updateData(); 
       request.setAttribute("data", object.getSentiment() + "updated last" + object.getLastUpdate()); 
       getServletContext().getRequestDispatcher("/login.jsp").forward(request, response); 
      } catch (NullPointerException x) { 
       Company object = Serializing.getCompany(Ticker); 
       request.setAttribute("data", "We do not have info on this stock"); 
       getServletContext().getRequestDispatcher("/login.jsp").forward(request, response); 
      } catch (Exception e) { 
       e.printStackTrace(); 
      } 
     } 


    } 
} 

Answer 1

如果你只想使用一個頁面和一個servlet，我認爲你可以使用session和response.sendRedirect（）來完成它。

這是index.jsp頁面

<h1>Search Stock</h1> 
    <form method="POST" action="DataServlet" onsubmit="dataCheck()"> 
     <input type="text" name="Symbol"> 
     <input type="submit" value="getData"> 
    </form> 

    <% 
     if(session.getAttribute("data") != null) { 
      out.print("<p>" + session.getAttribute("data")); 
      session.removeAttribute("data"); 
     } 
    %> 

    <script> 
     function dataCheck() { 
      if(document.getElementsByName[0].value == ""){ 
       alert("Symbol is null!"); 
       return false; 
      } 
      return true; 
     } 
    </script> 

這DataServlet類

public class DataServlet extends HttpServlet { 
    public void doPost(HttpServletRequest request, HttpServletResponse response) 
      throws ServletException, IOException { 
     String Ticker = request.getParameter("Symbol"); 
     Company object = Serializing.getCompany(Ticker); 

     if (object != null) { 
      object.updateData(); 
      request.getSession().setAttribute("data", object.getSentiment() + 
        "updated last" + object.getLastUpdate()); 
     } else { 
      request.getSession().setAttribute("data", "We do not have info on this stock"); 
     } 
     response.sendRedirect("index.jsp"); 
    } 
}