• MVC案例之新增与修改Customer


    新增Customer

    添加的流程
    Add New Customer 超链接连接到 newcustomer.jsp
    新建 newcustomer.jsp:

    在 CustomerServlet 的 addCustomer 方法中:参见注释

    上图一共有 2 个请求

    加载页面的请求:发出请求到页面加载完成,request 结束

    点击提交按钮,到 Serlvet,发出了一个 request,Serlvet 转发到 newcustomer.jsp 直到页面加载完成,整个过程一个 request

    doPost(request, response) ---> request.getRequestDispatcher(path).forward(request, response);

    private void addCustomer(HttpServletRequest request, HttpServletResponse response)
                throws ServletException, IOException {
            // 1.获取表单参数:name address phone
            String name = request.getParameter("name");
            String address = request.getParameter("address");
            String phone = request.getParameter("phone");
    
            // 2.检验 name 是否被占用
            // 2.1调用CustomerDAO的getCountWithName(String name) 获取 name 在数据库中是否存在
            long count = customerDAO.getCountWithName(name);
            // 2.2若返回值大于0,则响应 newcustomer.jsp 页面, 通过转发的方式响应newcustomer.jsp
            if (count > 0) {
                // 2.2.1要求页面显示一个错误消息: 用户名 name已经被占用,请重新选择,
                // 在request中放入一个属性message :用户名 name 已经被占用,请重新选择!
                // 在页面通过request.getAttribute("message")的方式显示
                request.setAttribute("message", "用户名 " + name + "已经被占用,请重新选择");
    
                // 2.2.2 newcustomer.jsp 的表单可以回显
                // 通过value="<%=request.getParameter("name") == null ? "" :
                // request.getParameter("name") %>"进行回显
    
                // 2.2.3结束方法:return
                request.getRequestDispatcher("/newcustomer.jsp").forward(request, response);
                return;
            }
            // 3.若验证通过,把表单参数封装为一个Customer 对象 customer
            Customer customer = new Customer(name, address, phone);
    
            // 4.调用CustomerDAO的 save(Customer customer) 执行保存操作
            customerDAO.save(customer);
    
            // 5.重定向的 success.jsp 页面:使用重定向可以避免表单的重复提交问题
            response.sendRedirect("success.jsp");
        }

    newcustomer.jsp

    <%@ page language="java" contentType="text/html; charset=UTF-8"
        pageEncoding="UTF-8"%>
    <!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=UTF-8">
    <title>Insert title here</title>
    </head>
    <body>
        <%
            Object msg = request.getAttribute("message");
            if (msg != null) {
        %>
        <br>
        <font color="red"><%=msg%></font>
        <br>
        <br>
        <%
            }
        %>
        <form action="addCustomer.do" method="post">
            <table>
                <tr>
                    <td>CustomerNam:</td>
                    <td><input type="text" name="name"
                        value="<%=request.getParameter("name") == null ? "" : request.getParameter("name")%>" /></td>
                </tr>
                <tr>
                    <td>Address:</td>
                    <td><input type="text" name="address"
                        value="<%=request.getParameter("address") == null ? "" : request.getParameter("address")%>" /></td>
                </tr>
                <tr>
                    <td>Phone:</td>
                    <td><input type="text" name="phone"
                        value="<%=request.getParameter("phone") == null ? "" : request.getParameter("phone")%>" /></td>
                </tr>
                <tr>
                    <td colspan="2"><input type="submit" value="Submit" /></td>
                </tr>
            </table>
        </form>
    </body>
    </html>

    修改:
    先显示(SELECT 操作)修改的页面,再进行修改(update)

    显示修改页面

    Update 的超链接:<a href="edit.do?id=<%= customer.getId() %>">UPDATE</a>

    edit 方法: 

    private void edit(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            String forwardPath = "/error.jsp";// 初始值
            // 1.获取请求参数 id
            String idStr = request.getParameter("id");
            // 2.调用CustomerDAO 的 customerDAO.get(id) 获取 id 对应的Customer 对象customer
            try {
                Customer customer = customerDAO.get(Integer.parseInt(idStr));
                if (customer != null) {// 当customer为null是转到 error.jsp
                    forwardPath = "/updatecustomer.jsp";
                    // 3.将customer放入request 中
                    request.setAttribute("customer", customer);
                }
            } catch (Exception e) {
            }
            // 4.响应updatecustomer.jsp 页面: 转发
            request.getRequestDispatcher(forwardPath).forward(request, response);
        }

    JSP 页面:

    获取请求域中的 Customer 对象,调用对应的字段的 get 方法来显示值。

    使用隐藏域来保存要修改的 Customer 对象的 id:<input type="hidden" name="id" value=“<%= customer.getId() %>"/>

    使用隐藏域来保存 oldName:<input type="hidden" name=“oldName" value=“<%= customer.getName() %>"/>

    关于隐藏域:和其他的表单域一样可以被提交到服务器,只不过在额页面上不显示

    提交到 update.do

    CustomerServlet

    package com.aff.mvcapp.servlet;
    import java.io.IOException;
    import java.lang.reflect.Method;
    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 com.aff.mvcapp.dao.CriteriaCustomer;
    import com.aff.mvcapp.dao.CustomerDAO;
    import com.aff.mvcapp.dao.impl.CustomerDAOImpl;
    import com.aff.mvcapp.domian.Customer;
    
    @WebServlet("/customerServlet")
    public class CustomerServlet extends HttpServlet {
        private static final long serialVersionUID = 1L;
    
        private CustomerDAO customerDAO = new CustomerDAOImpl();
    
        protected void doGet(HttpServletRequest request, HttpServletResponse response)
                throws ServletException, IOException {
            doPost(request, response);
        }
    
        protected void doPost(HttpServletRequest request, HttpServletResponse response)
                throws ServletException, IOException {
            // 1. 获取ServletPath: /edit.do 或 addCustomer.do
            String servletPath = request.getServletPath();
            // 2.去除 / 和 .do 得到类似于 edit 或 addCustomer 这样的字符串
            String methodName = servletPath.substring(1);
            methodName = methodName.substring(0, methodName.length() - 3);
    
            try {
                // 3.利用反射获取 methodName 对应的方法
                Method method = getClass().getDeclaredMethod(methodName, HttpServletRequest.class,
                        HttpServletResponse.class);
                // 4.利用反射调用对应的方法
                method.invoke(this, request, response);
            } catch (Exception e) {
                // e.printStackTrace();
                // 可以有一些响应
                response.sendRedirect("error.jsp");
            }
        }
    
        private void addCustomer(HttpServletRequest request, HttpServletResponse response)
                throws ServletException, IOException {
            // 1.获取表单参数:name address phone
            String name = request.getParameter("name");
            String address = request.getParameter("address");
            String phone = request.getParameter("phone");
    
            // 2.检验 name 是否被占用
            // 2.1调用CustomerDAO的getCountWithName(String name) 获取 name 在数据库中是否存在
            long count = customerDAO.getCountWithName(name);
            // 2.2若返回值大于0,则响应 newcustomer.jsp 页面, 通过转发的方式响应newcustomer.jsp
            if (count > 0) {
                // 2.2.1要求页面显示一个错误消息: 用户名 name已经被占用,请重新选择,
                // 在request中放入一个属性message :用户名 name 已经被占用,请重新选择!
                // 在页面通过request.getAttribute("message")的方式显示
                request.setAttribute("message", "用户名 " + name + "已经被占用,请重新选择");
    
                // 2.2.2 newcustomer.jsp 的表单可以回显
                // 通过value="<%=request.getParameter("name") == null ? "" :
                // request.getParameter("name") %>"进行回显
    
                // 2.2.3结束方法:return
                request.getRequestDispatcher("/newcustomer.jsp").forward(request, response);
                return;
            }
            // 3.若验证通过,把表单参数封装为一个Customer 对象 customer
            Customer customer = new Customer(name, address, phone);
    
            // 4.调用CustomerDAO的 save(Customer customer) 执行保存操作
            customerDAO.save(customer);
    
            // 5.重定向的 success.jsp 页面:使用重定向可以避免表单的重复提交问题
            response.sendRedirect("success.jsp");
    
        }
    
        private void edit(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            String forwardPath = "/error.jsp";// 初始值
            // 1.获取请求参数 id
            String idStr = request.getParameter("id");
            // 2.调用CustomerDAO 的 customerDAO.get(id) 获取 id 对应的Customer 对象customer
            try {
                Customer customer = customerDAO.get(Integer.parseInt(idStr));
    if (customer != null) {// 当customer为null是转到 error.jsp
                    forwardPath = "/updatecustomer.jsp";
                    // 3.将customer放入request 中
                    request.setAttribute("customer", customer);
                }
            } catch (Exception e) {
            }
            // 4.响应updatecustomer.jsp 页面: 转发
            request.getRequestDispatcher(forwardPath).forward(request, response);
    
        }
    
        private void update(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            // 1.获取表单参数:id,name,addres, phone, oldName
            String id = request.getParameter("id");
            String name = request.getParameter("name");
            String address = request.getParameter("address");
            String phone = request.getParameter("phone");
            String oldName = request.getParameter("oldName");
    
            // 2.检查name是否被占用
            // 2.比较name和oldName 是否相同,若相同说明 name可用
            // 2.1若不相同, 则调用CustomerDAO 的 getCountWithName(String name) 获取 name在数据库中是否存在
            if (!oldName.equalsIgnoreCase(name)) {
                long count = customerDAO.getCountWithName(name);
                if (count > 0) {
                    // 2.2若返回值大于0,则响应 updatecustomer.jsp 页面,
                    // 通过转发的方式响应updatecustomer.jsp
                    // 2.2.1要求页面显示一个错误消息: 用户名 name已经被占用,请重新选择,
                    // 在request中放入一个属性message :用户名 name 已经被占用,请重新选择!
                    // 在页面通过request.getAttribute("message")的方式显示
                    request.setAttribute("message", "用户名" + name + "已经被占用,请重新选择!");
    
                    // 2.2.2 updatecustomer.jsp 的表单可以回显
                    // address, phone 显示提交表单的新的值,而 name 显示oldName, 而不是新提交的 name
    
                    // 2.2.3结束方法:return
                    request.getRequestDispatcher("/updatecustomer.jsp").forward(request, response);
                    return;
                }
            }
            
            //3.若验证通过,则把表单参数封装为一个Customer 对象 customer
            Customer customer  = new Customer(name, address, phone);
            customer.setId(Integer.parseInt(id));//表单过来的 安全的
            
            //4.调用CustomerDAO 的 update(Customer customer) 执行更新操作
            customerDAO.update(customer);
            //5.重定向到    query.do
            response.sendRedirect("query.do");   
        }
    
    private void query(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { String name = request.getParameter("name"); String address = request.getParameter("address"); String phone = request.getParameter("phone"); CriteriaCustomer cc = new CriteriaCustomer(name, address, phone); // 1.调用 CustomerDAO 的 getForListWithCriteriaCustomer() 得到 Customer 的集合 List<Customer> customers = customerDAO.getForListWithCriteriaCustomer(cc); // 2.把 Customer 的集合放入 request 中 request.setAttribute("customers", customers); // 3.转发页面到 index.jsp 中( 不能使用重定向) request.getRequestDispatcher("/index.jsp").forward(request, response); } private void delete(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { String idstr = request.getParameter("id"); int id = 0; // try-catch的作用 , 防止恶意的输入, idStr 不能转为int类型,若出异常 id直接为0 try { id = Integer.parseInt(idstr); customerDAO.delete(id); } catch (Exception e) { } response.sendRedirect("query.do"); } }

    updatecustomer.jsp

    <%@page import="com.aff.mvcapp.domian.Customer"%>
    <%@ page language="java" contentType="text/html; charset=UTF-8"
        pageEncoding="UTF-8"%>
    <!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=UTF-8">
    <title>Insert title here</title>
    </head>
    <body>
        <%
            Object msg = request.getAttribute("message");
            if (msg != null) {
        %>
        <br>
        <font color="red"><%=msg%></font>
        <br>
        <br>
        <%
            }
        %>
    
        <%
            String id = null;
            String oldName = null;
            String name = null;
            String address = null;
            String phone = null;
    Customer customer
    = (Customer) request.getAttribute("customer"); if(customer != null){ id = customer.getId()+""; name = customer.getName(); oldName = customer.getName(); address = customer.getAddress(); phone = customer.getPhone(); }else{ id = request.getParameter("id");//旧的 name = request.getParameter("oldName");//旧的 oldName = request.getParameter("oldName");//旧的 address = request.getParameter("address");//新的 phone = request.getParameter("phone");//新的 } %> <form action="update.do" method="post"> <input type="hidden" name="id" value="<%=id%>" /> <input type="hidden" name="oldName" value="<%=oldName%>" /> <table> <tr> <td>CustomerNam:</td> <td><input type="text" name="name" value="<%=name%>" /></td> </tr> <tr> <td>Address:</td> <td><input type="text" name="address" value="<%=address%>" /></td> </tr> <tr> <td>Phone:</td> <td><input type="text" name="phone" value="<%=phone%>" /></td> </tr> <tr> <td colspan="2"><input type="submit" value="Submit" /></td> </tr> </table> </form> </body> </html>

    index.jsp

    <%@page import="com.aff.mvcapp.domian.Customer"%>
    <%@page import="java.util.List"%>
    <%@ page language="java" contentType="text/html; charset=UTF-8"
        pageEncoding="UTF-8"%>
    <!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=UTF-8">
    <title>Insert title here</title>
    <script type="text/javascript" src="scripts/jquery-1.12.3.js"></script>
    <script type="text/javascript">
        $(function() {
            $(".delete").click(function() {
                //找到tr的第二个td也就是name,再获取它的value值
                var content = $(this).parent().parent().find("td:eq(1)").text();
                var flag = confirm("确定要删除" + content + "的信息吗")
                return flag;
            });
        });
    </script>
    </head>
    <body>
    
    
        <form action="query.do" method="post">
            <table>
                <tr>
                    <td>CustomerNam:</td>
                    <td><input type="text" name="name" /></td>
                </tr>
                <tr>
                    <td>Address:</td>
                    <td><input type="text" name="address" /></td>
                </tr>
                <tr>
                    <td>Phone:</td>
                    <td><input type="text" name="phone" /></td>
                </tr>
                <tr>
                    <td><input type="submit" value="Query" /></td>
                  <td><a href="newcustomer.jsp">Add New Customer</a></td>
                </tr>
            </table>
        </form>
    
        <br />
        <br />
        <br />
        <br />
    
        <%
            List<Customer> customers = (List<Customer>) request.getAttribute("customers");
            if (customers != null && customers.size() > 0) {
        %>
        <hr>
        <br>
        <br>
        <table border="1" cellpadding="10" cellspacing="0">
            <tr>
                <td>ID</td>
                <td>CustomersName</td>
                <td>Address</td>
                <td>Phone</td>
                <td>UPDATEDELETE</td>
            </tr>
    
            <%
                for (Customer customer : customers) {
            %>
    
            <tr>
                <td><%=customer.getId()%></td>
                <td><%=customer.getName()%></td>
                <td><%=customer.getAddress()%></td>
                <td><%=customer.getPhone()%></td>
                <td><a href="edit.do?id=<%=customer.getId()%>">UPDATE</a> 
                    <a href="delete.do?id=<%=customer.getId()%>" class="delete">DELETE</a>
                </td>
            </tr>
    
            <%
                }
            %>
    
        </table>
    
        <%
            }
        %>
    
    </body>
    </html>
    All that work will definitely pay off
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  • 原文地址:https://www.cnblogs.com/afangfang/p/12735024.html
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