我已经为医院管理创建了项目..我想将表单字段值从jsp发送到servlet作为会话...我试过以下代码
Jsp页面：
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Add patient details</title>
</head>
<body>
<form action="Patientdetails" method="GET">
<fieldset>
<legend> <h1> Patient details </h1> </legend>
<center>
<table> <tr><td>
Patient's name: </td><td> <input type="text" name="name" placeholder="Enter the patients's name" value="deeban" pattern='[A-Za-z0-9]{5,15}' title="Doctor name should be minimum of 5 characters and maximum of 15 characters"/> </td></tr><tr><td><br></td></tr><tr><td>
Patient's age: </td><td> <input type="text" name = "age" placeholder="Enter the patients's age" pattern='[0-9]{2}' title="Enter age as two digit number"/> </td></tr><tr><td><br></td></tr><tr><td>
Gender : </td><td> <label for='male'>male</label> <input type="radio" name = "gender" id='gender' value='male' checked />
<label for ='female'>female</label><input type='radio' name = "gender" id='gender' value='female' /> </td></tr><tr><td><br></td></tr><tr><td>
Category of doctor to meet: </td><td><select name="cat">
<optgroup label="Select Category">
<option value="Dentist"> Dentist</option>
<option value="Cardiologist"> Cardiologist </option>
<option value="surgeon" selected>surgeon </option>
<option value="Diabetologists"> Diabetologists</option>
</optgroup> </select> </td></tr><tr><td><br></td></tr><tr><td>
Visiting time: </td><td><select name= "time" multiple>
<optgroup label="Available timings">
<option value="9:00A.M-12:00P.M (Morning)"> 9:00A.M-12:00P.M (Morning)</option>
<option value="12:00P.M-3:00P.M (Afternoon)">12:00P.M-3:00P.M (Afternoon)</option>
<option value="04:00P.M-7:00P.M (Evening)" selected>04:00P.M-7:00P.M (Evening)</option>
<option value="8:00P.M-12:00A.M (Night)">8:00P.M-12:00A.M (Night)</option>
</optgroup> </select> </td></tr><tr><td> <br></td></tr><tr><td>
Your token number:</td><td> <input type="text" name="token" value="14" readonly/>
</td></tr><tr><td><br></td></tr><tr><td>
<input type='submit' value='submit'> </td></tr>
<%
try {
String name, age, gender, cat, time, token;
name = (String) request.getAttribute("name");
age = request.getParameter("age");
gender = request.getParameter("gender");
cat = request.getParameter("cat");
time = request.getParameter("time");
token = request.getParameter("token");
request.getSession().setAttribute("name", name);
request.getSession(true).setAttribute("name", name); // firstway
session.setAttribute("name", name); //another way
session.setAttribute("age", age);
session.setAttribute("gender", gender);
session.setAttribute("cat", cat);
session.setAttribute("time", time);
session.setAttribute("token", token);
out.println("Session " + request.getSession().getAttribute("name").toString());
} catch (Exception e) {
out.println("The exception part is " + e);
}
%>
</table>
</center>
</fieldset>
</form>
</body>
Servlet页面：
package Patientdetails;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Enumeration;
import javax.jms.Session;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
public class Patientdetails extends HttpServlet {
HttpServletRequest request;
String[] pname = {"name", "age", "gender", "cat", "time", "token"};
String[] pvalue = new String[6];
protected void processRequest(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html;charset=UTF-8");
PrintWriter out = response.getWriter();
try {
out.println("<!DOCTYPE html>");
out.println("<html>");
out.println("<head>");
// out.println("<title>"+session.getAttribute("name")+"</title>");
out.println("</head>");
out.println("<body>");
} finally {
out.close();
}
}
@Override
public void init() {
}
@Override
public void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException {
PrintWriter out = response.getWriter();
try {
for (int i = 0; i < pname.length; i++) {
pvalue[i] = (String) request.getSession().getAttribute(pname[i]);
}
out.println("<table BORDER ='2'><th>Patient Name</th><th>Patient Age</th><th>Gender</th><th>Category of doctor </th><th>Appointment Time</th><th>Token no</th>");
out.println("<tr><td>" + pvalue[0] + "</td> <td>" + pvalue[1] + "</td><td>" + pvalue[2] + "</td><td>" + pvalue[3] + " </td><td> " + pvalue[4] + " </td><td> " + pvalue[5] + "</td></tr>");
out.println("<h1>The Session value is " + request.getSession().getAttribute("name")+"</h1>");
out.println("</body>");
out.println("</html>");
} catch (Exception e) {
out.println("Exception part " + e);
e.printStackTrace(out);
}
}
@Override
public void destroy() {
}
}
当我尝试这样的时候，我只是在servlet页面中获取null值。我不知道为什么它只是传递空值？有没有其他方法可以将值传递为session ???
答案 0 :(得分：1)
您需要清楚地了解哪些代码在浏览器中执行客户端，哪些代码正在执行服务器端。在脚本代码在JSP中执行的时刻，您的HTML表单尚未提交，因此request或session对象中没有存储任何表单值。这就是表单字段值为null的原因。
您应该移动代码以将提交的表单中的字段值检索到servlet，就像表单提交的那样（由action属性指定）。要从servlet中获取表单值，可以使用：
String paramValue = request.getParameter("paramName");
要从HTTP会话中检索值，请使用：
request.getSession().getAttribute("attributeName");
您通常不会从请求中检索参数值，以便将它们存储在会话中。让JSP会话作为范围开始更清晰。
顺便说一句，请注意您的HTML表单应该使用HTTP POST方法而不是GET，如果它不能安全地多次提交（通常是因为它改变了某些服务器端状态）。