Servlet+JSP实现人员新增

什么是mvc   

Controller（**Servlet）把数据封装成Model发给View显示

Model （Person）用户输入放到Model中传给Controller

View（jsp）只写for循环、颜色控制显示等，不在jsp中写业务逻辑代码

【知识点】

forward和sendRedirect都会导致浏览器收到一个响应，由于http协议规定一个请求只能对应一个响应，所以在进行forward或sendRedirect操作后，立即return，这样可以避免后面的代码再次生成响应从而导致错误

【注意】

setAttribute的使用周期  

sendRedirect和forward的选择

【PersonServlet.java】

查询和新增功能

package com.rupeng.web2;import java.io.IOException;import java.sql.ResultSet;import java.sql.SQLException;import java.util.LinkedList;import java.util.List;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;public class PersonServlet extends HttpServlet{@Overrideprotected void doPost(HttpServletRequest req, HttpServletResponse resp)throws ServletException, IOException{this.doGet(req, resp);}@Overrideprotected void doGet(HttpServletRequest req, HttpServletResponse resp)throws ServletException, IOException{String action = req.getParameter("action");if (action.equals("list")){try{ResultSet rs = JdbcUtils.executeQuery("select * from T_Persons2");// req.setAttribute("rs", rs);List<Person> list = new LinkedList<Person>();while (rs.next()){int id = rs.getInt("Id");String name = rs.getString("Name");int age = rs.getInt("Age");Person p = new Person();p.setId(id);p.setName(name);p.setAge(age);list.add(p);}JdbcUtils.closeAll(rs);// /REsultSet等一般不要传给jspreq.setAttribute("persons", list);// request中的数据有效期是“当前请求”// jsp中就可以从request总取出"persons"的值//！！！如果逻辑是服务器处理的，那么"/"一般可以表示“项目的WebRoot根目录”//如果逻辑是浏览器端处理的。req.getRequestDispatcher("/PersonList2.jsp").forward(req, resp);//req.getRequestDispatcher("/PersonList2_2.jsp").forward(req, resp);//resp.sendRedirect("/PersonList2.jsp");//resp.sendRedirect("PersonList2.jsp");//！！！如果写成sendRedirect，那么浏览器是发出两次请求的，两次请求中的request数据不能共享// 让/PersonList2.jsp进行数据的显示} catch (SQLException e){resp.getWriter().write("数据库查询错误");}}else if(action.equals("addnew")){//MVC中用户不直接和JSP打交道(地址栏中不会出现jsp)，JSP只是负责//req.getRequestDispatcher("/PersonList2.jsp").forward(req, resp);//之后数据的显示。用户永远直接和普通的Servlet打交道//由/PersonAddNew.jsp帮我处理吧。req.getRequestDispatcher("/PersonAddNew.jsp").forward(req, resp);}else if(action.equals("addnewSubmit")){String name= req.getParameter("name");int age = Integer.parseInt(req.getParameter("age"));try{JdbcUtils.executeUpdate("insert into T_Persons2(Name,Age) values(?,?)", name,age);resp.sendRedirect("person?action=list");} catch (SQLException e){req.setAttribute("msg","插入数据执行失败");//把jsp要用的数据放到reques中//让"/MyError.jsp"去显示数据req.getRequestDispatcher("/MyError.jsp").forward(req, resp);//resp.sendRedirect("MyError.jsp");}}else if(action.equals("edit")){int id = Integer.parseInt(req.getParameter("id"));try{ResultSet rs = JdbcUtils.executeQuery("select * from T_Persons2 where Id=?", id);if(rs.next()){Person person = new Person();person.setId(id);person.setName(rs.getString("Name"));person.setAge(rs.getInt("Age"));req.setAttribute("person", person);req.getRequestDispatcher("/PersonEdit.jsp").forward(req, resp);}else{req.setAttribute("msg", "没有找到id="+id+"的人员");req.getRequestDispatcher("/MyError.jsp").forward(req, resp);}JdbcUtils.closeAll(rs);} catch (SQLException e){req.setAttribute("msg", "数据查询出错");req.getRequestDispatcher("/MyError.jsp").forward(req, resp);}}else if(action.equals("editSubmit")){int id = Integer.parseInt(req.getParameter("id"));String name = req.getParameter("name");int age = Integer.parseInt(req.getParameter("age"));try{JdbcUtils.executeUpdate("Update T_Persons2 set Name=?,Age=? where Id=?", name,age,id);resp.sendRedirect("person?action=list");} catch (SQLException e){req.setAttribute("msg", "保存出错");req.getRequestDispatcher("/MyError.jsp").forward(req, resp);}}else if (action.equals("delete")){int id = Integer.parseInt(req.getParameter("id"));try{JdbcUtils.executeUpdate("delete from  T_Persons2 where Id=?",id);resp.sendRedirect("person?action=list");} catch (SQLException e){req.setAttribute("msg", "删除出错");req.getRequestDispatcher("/MyError.jsp").forward(req, resp);}}}}

【PersonList2.jsp】

显示人员列表

<%@ page language="java" contentType="text/html; charset=UTF-8"    pageEncoding="UTF-8"%><%@page import="java.util.List"%><%@page import="com.rupeng.web2.Person"%><!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>人员列表</title></head><body><p><a href="person?action=addnew">新增</a></p><table><thead><tr><td>Id</td><td>姓名</td><td>年龄</td><td>编辑</td><td>删除</td></tr></thead><tbody><%List<Person> persons = (List<Person>)request.getAttribute("persons");for(Person person : persons){%><tr><td><%=person.getId() %></td><td><%=person.getName() %></td><td><%=person.getAge() %></td><td><a href="person?action=edit&id=<%=person.getId() %>">编辑</a></td><td><a href="person?action=delete&id=<%=person.getId() %>">删除</a></td></tr><%} %></tbody></table></body></html>

【PersonAddNew.jsp】

显示新增人员页面

<%@ 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>新增人员</title></head><body><form action="person" method="post"><input type="hidden" name="action" value="addnewSubmit"/>姓名：<input type="text" name="name"/>年龄：<input type="text" name="age"/><input type="submit" value="保存"/></form></body></html>

【PersonEdit.jsp】

<%@ page language="java" contentType="text/html; charset=UTF-8"<span style="white-space:pre"></span>import="com.rupeng.web2.Person"    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>编辑</title></head><body><%Person person = (Person)request.getAttribute("person");%><form action="person" method="post"><input type="hidden" name="action" value="editSubmit"/><input type="hidden" name="id" value="<%=person.getId() %>"/>姓名：<input type="text" name="name" value="<%=person.getName() %>"/>年龄：<input type="text" name="age" value="<%=person.getAge() %>"/><input type="submit" value="保存"/></form></body></html>

【MyError.jsp】

显示错误页面

<%@ 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>错误</title></head><body> <%=request.getAttribute("msg") %></body></html>

【web.xml】

<?xml version="1.0" encoding="UTF-8"?><web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"><welcome-file-list><welcome-file>index.jsp</welcome-file></welcome-file-list><error-page><exception-type>java.lang.Throwable</exception-type><location>/Error.jsp</location></error-page><error-page><error-code>404</error-code><location>/muyou.html</location></error-page> <servlet><servlet-name>personServlet</servlet-name><servlet-class>com.rupeng.web2.PersonServlet</servlet-class></servlet><servlet-mapping><servlet-name>personServlet</servlet-name><url-pattern>/person</url-pattern></servlet-mapping></web-app>

【Person.java】

package com.rupeng.web2;public class Person{private int id;private String name;private int age;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 int getAge(){return age;}public void setAge(int age){this.age = age;}}

其余引用【JdbcUtils.java】