Java 将信息从Servlet发送回JSP
用户单击index.jsp页面上的edit，然后将其发送到editCustomer.jsp页面。问题是，当我单击“更新”时，它不会更新索引页上的客户信息 如何使用我拥有的代码来实现这一点 INDEX.JSPJava 将信息从Servlet发送回JSP,java,jsp,servlets,Java,Jsp,Servlets,用户单击index.jsp页面上的edit，然后将其发送到editCustomer.jsp页面。问题是，当我单击“更新”时，它不会更新索引页上的客户信息 如何使用我拥有的代码来实现这一点 INDEX.JSP 我不确定你期望发生什么。您正在提交此表单 <form method='get' action='customer'> <table> <tr> <td>Name:</td>
我不确定你期望发生什么。您正在提交此表单
<form method='get' action='customer'>
<table>
<tr>
<td>Name:</td>
<td>
"
<input name='name' />
</td>
</tr>
<tr>
<td>City:</td>
<td>
<input name='city' />
</td>
</tr>
<tr>
<td colspan='2' style='text-align:right'>
<input type='submit' value='Update' />
</td>
</tr>
<tr>
<td colspan='2'>
<a href='customer'>Customer List</a>
</td>
</tr>
</table>
</form>
POSTid考虑一下请求-响应周期
您的Servlet容器接收到一个HTTP请求，它会分派您的Servlet来处理它。servlet执行一些逻辑并转发给JSP。JSP呈现一些写入HTTP响应主体的HTML。响应被发送到客户端。在本例中，您的客户端是一个浏览器，它读取HTML文本并以图形方式呈现。然后，您可以与它交互，填写输入字段并单击按钮。执行此操作时，浏览器将获取您输入的值并生成一个HTTP请求，并将该请求发送到服务器。等等，等等…无论你做什么，都不要使用Scriptlet。它可能是隐藏字段吗？@user2939808绝对是。但是你不想让用户选择哪个吗？不，当我单击“编辑”时，它会将我发送到表单IE editcustomer，并在url中为任何用户指定id。现在我只需要得到信息更新，当它重定向到索引页。我添加了一个隐藏字段（参见代码），但没有发生与此相同的情况before@user2939808你没有给它一个值，但在servlet中我给了。我想这就是我被困的地方。
<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
pageEncoding="ISO-8859-1"%>
<%@page import="edu.witc.Assignment02.controller.CustomerServlet"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Edit Customer</title>
</head>
<body>
<h2>Edit Customer</h2>
<% int customerId =
Integer.parseInt(request.getParameter("id"));%>
<form method='post' action='customer'>
<input type='hidden' name ='id' value='<%=customerId%>'/>
<table>
<tr><td>Name:</td><td>"
<input name='name' />
</td></tr>
<tr><td>City:</td><td>
<input name='city' />
</td></tr>
<tr>
<td colspan='2' style='text-align:right'>
<input type='submit' value='Update'/></td>
</tr>
<tr><td colspan='2'>
<a href='customer'>Customer List</a>
</td></tr>
</table>
</form></body>
</html>
package edu.witc.Assignment02.controller;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.List;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import edu.witc.Assignment02.*;
import edu.witc.Assignment02.model.Customer;
/*
* Not thread-safe. For illustration purpose only
*/
@WebServlet(name = "CustomerServlet", urlPatterns = {
"/customer", "/editCustomer", "/updateCustomer"})
public class CustomerServlet extends HttpServlet {
private static final long serialVersionUID = -20L;
private List<edu.witc.Assignment02.model.Customer> customers = new ArrayList<Customer>();
@Override
public void init() throws ServletException {
Customer customer1 = new Customer();
customer1.setId(1);
customer1.setName("Donald D.");
customer1.setCity("Miami");
customers.add(customer1);
Customer customer2 = new Customer();
customer2.setId(2);
customer2.setName("Mickey M.");
customer2.setCity("Orlando");
customers.add(customer2);
}
private void sendCustomerList(HttpServletResponse response, HttpServletRequest request)//redirect to index
throws IOException, ServletException {
String url = "/index.jsp";
request.setAttribute("customers", customers);
request.getRequestDispatcher(url).forward(request,response);
}
private Customer getCustomer(int customerId) {
for (Customer customer : customers) {
if (customer.getId() == customerId) {
return customer;
}
}
return null;
}
private void sendEditCustomerForm(HttpServletRequest request,
HttpServletResponse response) throws IOException, ServletException {
String url = "/editCustomer.jsp";
request.setAttribute("customers", customers);
request.getRequestDispatcher(url).forward(request,response);
}
@Override
public void doGet(HttpServletRequest request,
HttpServletResponse response)
throws ServletException, IOException {
String uri = request.getRequestURI();
if (uri.endsWith("/customer")) {
sendCustomerList(response, request);
} else if (uri.endsWith("/editCustomer")) {
sendEditCustomerForm(request, response);
}
}
@Override
public void doPost(HttpServletRequest request,
HttpServletResponse response)
throws ServletException, IOException, ServletException {
// update customer
int customerId = 0;
try {
customerId =
Integer.parseInt(request.getParameter("id"));
} catch (NumberFormatException e) {
}
Customer customer = getCustomer(customerId);
if (customer != null) {
customer.setName(request.getParameter("name"));
customer.setCity(request.getParameter("city"));
}
sendCustomerList(response, request);
}
}
package edu.witc.Assignment02.model;
public class Customer {
private int id;
private String name;
private String city;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getCity() {
return city;
}
public void setCity(String city) {
this.city = city;
}
}
<form method='get' action='customer'>
<table>
<tr>
<td>Name:</td>
<td>
"
<input name='name' />
</td>
</tr>
<tr>
<td>City:</td>
<td>
<input name='city' />
</td>
</tr>
<tr>
<td colspan='2' style='text-align:right'>
<input type='submit' value='Update' />
</td>
</tr>
<tr>
<td colspan='2'>
<a href='customer'>Customer List</a>
</td>
</tr>
</table>
</form>
if (uri.endsWith("/customer")) {
sendCustomerList(response, request);
private void sendCustomerList(HttpServletResponse response, HttpServletRequest request)//redirect to index
throws IOException, ServletException {
String url = "/index.jsp";
request.setAttribute("customers", customers);
request.getRequestDispatcher(url).forward(request,response);
}