使用jsp、HttpServlet完成一个登录、注册,并用MySQL连接数据进行操作

第一步 我们先MySQL创建数据库，写数据

这两个是写数据库的软件。

 启动MySQL对应的版本型号。

user表

1.判断存在（有没有login的数据库，有就删掉）即删除。

DROP DATABASE IF EXISTS login;

2.创建数据库，使用数据库

 #创建数据库
CREATE DATABASE login;
#使用数据库
use login;

3.创建一个表我们这定义叫user，给表增添3条数据

#创建表
CREATE TABLE user(
    uid int PRIMARY KEY AUTO_INCREMENT,
    uname VARCHAR(32),
    password VARCHAR(32),
    phone VARCHAR(11),
    address VARCHAR(64)
);

INSERT INTO user(uname,password,phone,address) VALUES('张三','666','18965423548','南阳');
INSERT INTO user(uname,password,phone,address) VALUES('李四','333','18754263548','许昌');
INSERT INTO user(uname,password,phone,address) VALUES('小美','123','18565234759','信阳');
 

 4.查询表

SELECT * FROM user;

goods表

1.创建另一个表叫goods，给表增添3条数据

create table goods(
    gid int PRIMARY KEY AUTO_INCREMENT,
    gname VARCHAR(32),
    price DOUBLE,
    mark VARCHAR(128)
);

INSERT INTO goods(gname,price,mark) VALUES('泡面',4.5,'够香够辣就是这个味！');
INSERT INTO goods(gname,price,mark) VALUES('火腿',8.5,'肉质细腻Q弹！');
INSERT INTO goods(gname,price,mark) VALUES('雪碧',3.5,'清爽冰凉随心爽！');

  2.查询表

select * from goods;

整体代码如下： 

#判断存在即删除
DROP DATABASE IF EXISTS login;
#创建数据库
CREATE DATABASE login;
#使用数据库
use login;#创建表
CREATE TABLE user(uid int PRIMARY KEY AUTO_INCREMENT,uname VARCHAR(32),password VARCHAR(32),phone VARCHAR(11),address VARCHAR(64)
);INSERT INTO user(uname,password,phone,address) VALUES('张三','666','18965423548','南阳');
INSERT INTO user(uname,password,phone,address) VALUES('李四','333','18754263548','许昌');
INSERT INTO user(uname,password,phone,address) VALUES('小美','123','18565234759','信阳');SELECT * FROM user WHERE uname = ? AND password = ?;
SELECT * FROM user;create table goods(gid int PRIMARY KEY AUTO_INCREMENT,gname VARCHAR(32),price DOUBLE,mark VARCHAR(128)
);INSERT INTO goods(gname,price,mark) VALUES('泡面',4.5,'够香够辣就是这个味！');
INSERT INTO goods(gname,price,mark) VALUES('火腿',8.5,'肉质细腻Q弹！');
INSERT INTO goods(gname,price,mark) VALUES('雪碧',3.5,'清爽冰凉随心爽！');select * from goods;

 效果如下：

第二步 在IDEA中写出这两个表对应的Java实体类 

MySQL的表名要跟Java类(首字母大写)的表名一样 

User类

package com.chen.bean;public class User {private Integer id;private String uname;private String password;private String phone;private String address;public User() {}public User(Integer id, String uname, String password, String phone, String address) {this.id = id;this.uname = uname;this.password = password;this.phone = phone;this.address = address;}public Integer getId() {return id;}public void setId(int id) {this.id = id;}public String getUname() {return uname;}public void setUname(String uname) {this.uname = uname;}public String getPassword() {return password;}public void setPassword(String password) {this.password = password;}public String getPhone() {return phone;}public void setPhone(String phone) {this.phone = phone;}public String getAddress() {return address;}public void setAddress(String address) {this.address = address;}@Overridepublic String toString() {return "User{" +"id=" + id +", uname='" + uname + '\'' +", password='" + password + '\'' +", phone='" + phone + '\'' +", address='" + address + '\'' +'}';}
}

Goods类

package com.chen.bean;class Goods {private Integer gid;private String gname;private Double price;private String mark;public Goods(Integer gid, String gname, Double price, String mark) {this.gid = gid;this.gname = gname;this.price = price;this.mark = mark;}public Goods() {}@Overridepublic String toString() {return "zhuye{" +"gid=" + gid +", gname='" + gname + '\'' +", price=" + price +", mark='" + mark + '\'' +'}';}public Integer getGid() {return gid;}public void setGid(Integer gid) {this.gid = gid;}public String getGname() {return gname;}public void setGname(String gname) {this.gname = gname;}public Double getPrice() {return price;}public void setPrice(Double price) {this.price = price;}public String getMark() {return mark;}public void setMark(String mark) {this.mark = mark;}
}

第三步   在web下的.jsp中写出 首页(index.jsp) ，登录失败页面(error.jsp) ，登录页面(login.jsp)， 注册页面(register.jsp)，主页(zhuye.jsp)，添加页面（addGoods.jsp），修改页面（showGoods）。

1.首页

<%--Created by IntelliJ IDEA.User: chengeDate: 2023/2/13Time: 19:09To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head><title>这是一个web项目</title>
</head>
<body style ="background-image: url(img/01.jpg); background-size: 100% 100%">
<div align="center" style="width: 80px; height: 80px; margin:250px auto ; fbacground-color: rgba(170,223,255,70%)">
<a href="login.jsp" style="font-size: 30px">登录</a>
<a href="register.jsp" style="font-size: 30px">注册</a>
</div>
</body>
</html>

 2.登录页面

<%--Created by IntelliJ IDEA.User: chengeDate: 2023/2/14Time: 10:35To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head><title>登录页</title>
</head>
<body><form action="login" method="post">账号:<input type="text" name="uname" value=""><br>密码:<input type="password" name="password" value=""><br><input type="submit" value="登录">&nbsp;&nbsp;&nbsp;<a href="register.jsp">没有账号?请注册</a></form></body>
</html>

 3.登录失败页面

<%--Created by IntelliJ IDEA.User: chengeDate: 2023/2/17Time: 19:58To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head><title>错误页</title>
</head>
<body style="margin:200px auto">
<h1>出错啦</h1>
<a href="login.jsp">返回登录</a>
</body>
</html>

 4.注册页面

<%--Created by IntelliJ IDEA.User: chengeDate: 2023/2/14Time: 10:35To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head><title>zhuce</title>
</head>
<body>
<form action="register" method="post">账号:<input type="text" name="uname" value=""><br>密码:<input type="password" name="password" value=""><br>手机号:<input type="text" name="phone" value=""><br>地址:<input type="text" name="address" value=""><br>确认密码:<input type="password" name="password1" value=""><br><input type="submit" value="注册页面">&nbsp;&nbsp;&nbsp;<a href="login.jsp">已有账号?请登录</a>
</form>
</body>
</html>

 5.登录成功进入的主页面

由后台数据库传递过来的商品数据。

<%

之间可以写服务器端代码

%>

<%=%>获取后台的变量值

   session在网络应用中称为“会话控制”，是服务器为了保存用户状态而创建的一个特殊的对象。简而言之，session就是一个对象，用于存储信息。 

<%--Created by IntelliJ IDEA.User: chengeDate: 2023/2/17Time: 19:35To change this template use File | Settings | File Templates.
--%>
<%@taglib prefix="a" uri="http://java.sun.com/jsp/jstl/core" %>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head><title>主页</title>
</head>
<body style="background-image: url(img/01.jpg); background-size: 100% 100% "><!-- EL 表达式 通过 $ { }从作用域对象中获取数据，如果该数据库是对象，则可以通过是对象名，属性名获取其数值-->
<h2>欢迎来自${user.address}的${user.uname}访问项目主页</h2>
<form action="seach" method="post"><input type="text" name="keyword" value=""><input type="submit" value="搜索">
</form>
<a href="addGoods.jsp">添加商品</a>
<table ><thead><tr><th>商品编号</th><th>商品名称</th><th>商品价格</th><th>商品说明</th></tr></thead><tbody id="list"  ><!--items:要遍历的集合对象  var：集合中对应的临时对象--><a:forEach items="${goodsList}" var="goods"><tr><td>${goods.gid}</td><td>${goods.gname}</td><td>${goods.price}</td><td>${goods.mark}</td><td><a href="findById?gid=${goods.gid}">修改</a><a href="del?gid=${goods.gid}" onclick="return confirm('确定将此条数据删除?')">删除</a></td></tr></a:forEach></tbody>
</table>
</body>
</html>

6.添加页面

<%--Created by IntelliJ IDEA.User: chengeDate: 2023/2/25Time: 13:36To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head><title>商品信息的添加</title>
</head>
<body>
<form action="addGoods" method="post" >商品名称:<input type="text" name="gname" value="" placeholder="商品名称"><br>商品价格:<input type="number" step="0.01"  name="price" value="" placeholder="商品价格"><br>商品说明:<input type="text" name="mark" value="" placeholder="商品说明"><br><input type="submit" value="添加商品">
</form>
</body>
</html>

7.修改页面

 

<%--Created by IntelliJ IDEA.User: chengeDate: 2023/2/27Time: 8:27To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head><title>商品信息的修改</title>
</head>
<body>
<body>
<h2>商品修改</h2>
<form action="updateGoods" method="post">商品编号:<input type="text" name="gid" value="${goods.gid}" placeholder="商品编号" readonly="readonly"><br>商品名称:<input type="text" name="gname" value="${goods.gname}" placeholder="商品名称"><br>商品价格:<input type="number" step="0.01"  name="price" value="${goods.price}" placeholder="商品价格"><br>商品说明:<input type="text" name="mark" value="${goods.mark}" placeholder="商品说明"><br><input type="submit" value="修改商品">
</form>
</body>
</body>
</html>

 第四步 JDBC操作层面

1.在src里建三个包  Dao，httpServlet，Util

 2.在Dao中先创建两个接口 这里起名叫UserDao，GoodsDao

UserDao

login登录页面有两个参数

register 返回一个user对象

package com.chen.Dao;import com.chen.bean.User;public interface UserDao {/*** 完成登陆操作* @param uname 用户名* @param password 密码* @return  数据库查询的用户信息对象*/User login(String uname,String password);/*** 注册用户* @param user  封装的注册信息* @return  受影响的行数*/int register(User user);
}

 GoodsDao

这里我们写方法，在impl里GoodsDaoImpl中调用方法。

package com.chen.Dao;import com.chen.bean.Goods;import java.util.List;public interface GoodsDao {//全查public List<Goods> slectAll();public Goods selectById(int gid);//增public int selectInsert(Goods goods);//删public int selectDelete(int gid);//改public int selectUpdate(Goods goods);
}

3.再在Dao.impl中创建UserDaoImpl类，用这个类去继承UserDao接口，这里面写登录、注册JDBC的操作，用了分层操作，JDBC驱动、连接、调用方法、关闭资源 都在Util包中，httpservlet里写。

        util包-JDBCUtil类

package com.chen.Util;import com.chen.bean.User;import java.security.PublicKey;
import java.sql.*;public class JDBCUtil {private static String driver = "com.mysql.cj.jdbc.Driver";private static String url = "jdbc:mysql://127.0.0.1:3306/login?useSSL=false&serverTimezone=UTC";private static String user = "root";private static String password = "root";private static Connection conn = null;public static Connection getCon() {try {//1.加载数据库驱动Class.forName(driver);//2.获取数据库连接conn = DriverManager.getConnection(url, user, password);} catch (Exception e) {e.printStackTrace();}return conn;}//JDBCUtil.getCon()方法public static void main(String[] args) {System.out.println(JDBCUtil.getCon());}//登录的关闭资源public static void close(ResultSet rs,PreparedStatement pstm,Connection conn) {try {if (rs!=null){rs.close();}if (pstm!=null){pstm.close();}if (conn!=null){conn.close();}}catch (Exception e){e.printStackTrace();}}//注册的关闭资源public static void close(PreparedStatement pstm, Connection conn) {try {if (pstm!=null){pstm.close();}if (conn!=null){conn.close();}}catch (Exception e){e.printStackTrace();}}
}

 UserDaoImpl

package com.chen.Dao.imlp;import com.chen.Dao.UserDao;
import com.chen.Util.JDBCUtil;
import com.chen.bean.User;import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;public class UserDaoImpl implements UserDao {User login = null;Connection conn = null;  //数据库连接对象PreparedStatement pstm = null;  //预处理对象ResultSet rs = null;  //结果集对象int i = 0;//登录public User login (String uname, String password){try{conn = JDBCUtil.getCon();//3.sql语句String sql = "select * from user where uname=? and password=?";//4.获取预处理对象pstm = conn.prepareStatement(sql);//5.传参pstm.setObject(1,uname);pstm.setObject(2,password);//6.执行查询rs = pstm.executeQuery();//7.解析结果集if (rs.next()){login = new User();//从结果集中获取数据，封装到实体类对象中int uid = rs.getInt("uid");login.setId(uid);login.setUname(rs.getString("uname"));login.setPassword(rs.getString("password"));login.setPhone(rs.getString("phone"));login.setAddress(rs.getString("address"));}} catch (Exception throwables) {throwables.printStackTrace();}finally {//8.关闭资源JDBCUtil.close(rs,pstm,conn);}return login;}@Override//注册public int register(User user) {try {conn = JDBCUtil.getCon();String sql = "insert into user(uname,password,phone,address) values(?,?,?,?)";pstm = conn.prepareStatement(sql);pstm.setObject(1,user.getUname());pstm.setObject(2,user.getPassword());pstm.setObject(3,user.getPhone());pstm.setObject(4,user.getAddress());i = pstm.executeUpdate();} catch (Exception e) {e.printStackTrace();}finally {JDBCUtil.close(pstm,conn);}return i;}
}

 GoodsDaoImpl

在这里面就要完成全查的操作、添加操作、删除操作、修改操作根据id查找那条数据展现在页面中，再去写sql的修改代码操作。

package com.chen.Dao.imlp;import com.chen.Dao.GoodsDao;
import com.chen.Util.JDBCUtil;
import com.chen.bean.Goods;
import com.chen.bean.User;import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.util.ArrayList;
import java.util.List;public class GoodsDaoImpl implements GoodsDao {private User login = null;private Connection conn = null;  //数据库连接对象private PreparedStatement pstm = null;  //预处理对象private ResultSet rs = null;  //结果集对象private int i = 0; //增删改受影响的行数//全查@Overridepublic List<Goods> slectAll() {List<Goods> goodslist = new ArrayList<>();try {conn = JDBCUtil.getCon();//3.sql语句String sql = "select * from goods";//4.获取预处理对象pstm = conn.prepareStatement(sql);//5.执行查询rs = pstm.executeQuery();Goods goods=null;//6.解析结果集while (rs.next()){goods = new Goods();goods.setGid(rs.getInt("gid"));goods.setGname(rs.getString("gname"));goods.setPrice(rs.getDouble("price"));goods.setMark(rs.getString("mark"));goodslist.add(goods);}}catch (Exception e){e.printStackTrace();}finally {try {if (rs!=null){rs.close();}if (pstm!=null){pstm.close();}if (conn!=null){conn.close();}}catch (Exception e){e.printStackTrace();}}return goodslist;
}//模糊查询public List<Goods> seach(String keyword) {List<Goods> goodslist = new ArrayList<>();try {conn = JDBCUtil.getCon();//3.sql语句String sql = "select * from goods where gname like concat('%',?,'%')";//4.获取预处理对象pstm = conn.prepareStatement(sql);pstm.setObject(1,keyword);//5.执行查询rs = pstm.executeQuery();//6.解析结果集while (rs.next()){goods = new Goods();goods.setGid(rs.getInt("gid"));goods.setGname(rs.getString("gname"));goods.setPrice(rs.getDouble("price"));goods.setMark(rs.getString("mark"));goodslist.add(goods);}}catch (Exception e){e.printStackTrace();}finally {try {if (rs!=null){rs.close();}if (pstm!=null){pstm.close();}if (conn!=null){conn.close();}}catch (Exception e){e.printStackTrace();}}return goodslist;}//id查询public Goods selectById(int gid){Goods goods = null;try {conn = JDBCUtil.getCon();//3.sql语句String sql = "select * from goods where gid=?";//4.获取预处理对象pstm = conn.prepareStatement(sql);pstm.setObject(1,gid);//5.执行查询rs = pstm.executeQuery();//6.解析结果集if (rs.next()){goods = new Goods();goods.setGid(rs.getInt("gid"));goods.setGname(rs.getString("gname"));goods.setPrice(rs.getDouble("price"));goods.setMark(rs.getString("mark"));}}catch (Exception e){e.printStackTrace();}finally {try {if (rs!=null){rs.close();}if (pstm!=null){pstm.close();}if (conn!=null){conn.close();}}catch (Exception e){e.printStackTrace();}}return goods;}//添加数据@Overridepublic int selectInsert(Goods goods) {try {conn = JDBCUtil.getCon();//3.sql语句String sql = "insert into goods(gname,price,mark) values (?,?,?)";//4.获取预处理对象pstm = conn.prepareStatement(sql);pstm.setObject(1,goods.getGname());pstm.setObject(2,goods.getPrice());pstm.setObject(3,goods.getMark());//5.执行查询i = pstm.executeUpdate();}catch (Exception e){e.printStackTrace();}finally {try {if (pstm!=null){pstm.close();}if (conn!=null){conn.close();}}catch (Exception e){e.printStackTrace();}}return i;}//删除@Overridepublic int selectDelete(int gid) {System.out.println("selectDelete");try {conn = JDBCUtil.getCon();//3.sql语句String sql = "delete  from goods where gid=?";//4.获取预处理对象pstm = conn.prepareStatement(sql);pstm.setObject(1,gid);//5.执行查询i = pstm.executeUpdate();}catch (Exception e){e.printStackTrace();}finally {try {if (pstm!=null){pstm.close();}if (conn!=null){conn.close();}}catch (Exception e){e.printStackTrace();}}return i;}
//修改@Overridepublic int selectUpdate(Goods goods) {try {conn = JDBCUtil.getCon();//3.sql语句String sql = "update goods set gname=?,price=?,mark=? where gid=?";//4.获取预处理对象pstm = conn.prepareStatement(sql);pstm.setObject(1,goods.getGname());pstm.setObject(2,goods.getPrice());pstm.setObject(3,goods.getMark());pstm.setObject(4,goods.getGid());//5.执行查询i = pstm.executeUpdate();System.out.println("i="+i);}catch (Exception e){e.printStackTrace();}finally {try {if (pstm!=null){pstm.close();}if (conn!=null){conn.close();}}catch (Exception e){e.printStackTrace();}}return i;}}

 第五步 业务处理层面

httpServlet中写的三个类是处理 ：

1.设置请求和响应的编码格式2.获取请求的参数3.执行业务处理

Login

1.映射地址

@WebServlet("/login")

请求：

request.getRequestDispatcher("        ").forward(request,response);//请求别的地址

package com.chen.httpServlet;import com.chen.Dao.UserDao;
import com.chen.Dao.imlp.UserDaoImpl;
import com.chen.bean.User;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 java.io.IOException;@WebServlet("/login")
public class Login extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {System.out.println("Login-get");doPost(request,response);}@Overrideprotected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {System.out.println("Login-post");//前端请求（request），后端处理后，最后给前端做出响应（response）//1.设置请求和响应的编码格式，以及响应的格式request.setCharacterEncoding("utf-8");  //设置请求的编码格式为中文response.setCharacterEncoding("utf-8");    //设置响应的编码格式response.setContentType("text/html;charset=UTF-8");  //以什么样的格式 （文本/网页）响应//2.获取请求的参数String uname = request.getParameter("uname"); //根据表单的name属性获取用户输入的值String password = request.getParameter("password");//3.执行业务处理UserDao userDao = new UserDaoImpl();User login = userDao.login(uname,password);//判断登录的用户信息是否为空if (login!=null) {System.out.println("登录成功！");//登录成功,当前servlet的业务处理完毕----后续执行查询商品的操作应该由别人来完成---请求转发给别的servlet处理request.getRequestDispatcher("selectAllGoods").forward(request,response);//请求别的地址} else {//登录失败，跳转到错误页response.sendRedirect("error.jsp");}}
}

 Register

1.映射地址

@WebServlet("/register")

package com.chen.httpServlet;import com.chen.Dao.UserDao;
import com.chen.Dao.imlp.UserDaoImpl;
import com.chen.bean.User;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 java.io.IOException;
import java.sql.*;@WebServlet("/register")
public class Register extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {System.out.println("register-get");doPost(request,response);}@Overrideprotected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {System.out.println("register-post");//1.设置请求和响应的编码格式，以及响应的格式request.setCharacterEncoding("utf-8");  //设置请求的编码格式为中文response.setCharacterEncoding("utf-8");    //设置响应的编码格式//2.获取请求的参数String uname = request.getParameter("uname"); //根据表单的name属性获取用户输入的值String password = request.getParameter("password");String phone = request.getParameter("phone");String address = request.getParameter("address");//封装：把上面所有的变量装载到User对象中User user = new User();user.setUname(uname);user.setPassword(password);user.setPhone(phone);user.setAddress(address);System.out.println(user);//3.执行业务处理UserDao userDao = new UserDaoImpl();int i = userDao.register(user);//判断登录的用户信息是否为空if (i > 0) {//注册成功，跳转到登录页面response.sendRedirect("login.jsp");//指定跳转的页面} else {//登录失败，跳转到错误页response.sendRedirect("register.jsp");}}}

 SelectAllGoods

1.映射地址

@WebServlet("/selectAllGoods")

//通过request获取session对象，该对象可以向前端传递传输数据的容器HttpSession               session = req.getSession();

package com.chen.httpServlet;import com.chen.Dao.imlp.GoodsDaoImpl;
import com.chen.bean.Goods;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 javax.servlet.http.HttpSession;
import java.io.IOException;
import java.util.List;@WebServlet("/selectAllGoods")
public class SelectAllGoods extends HttpServlet {@Overrideprotected void doPut(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {doPost(req, resp);}@Overrideprotected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {System.out.println("SelectAllGoods..dopost");//查询所有商品信息GoodsDaoImpl goodsDao = new GoodsDaoImpl();List<Goods> goodsList = goodsDao.slectAll();System.out.println(goodsList);//把数据传递到前端页面//通过request获取session对象，该对象可以向前端传递传输数据的容器HttpSession session = req.getSession();//向session 中存入商品信息集合session.setAttribute("goodsList", goodsList);//登录成功，跳转到主页resp.sendRedirect("zhuye.jsp");//指定的跳转页面}
}

InsertGoods

1.映射地址

@WebServlet("/addGoods")

package com.chen.httpServlet;import com.chen.Dao.GoodsDao;
import com.chen.Dao.imlp.GoodsDaoImpl;
import com.chen.bean.Goods;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 java.io.IOException;@WebServlet("/addGoods")
public class InsertGoods extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {doPost(req, resp);}@Overrideprotected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {req.setCharacterEncoding("UTF-8");resp.setCharacterEncoding("UTF-8");//获取请求参数并封装到Goods对象中Goods goods = new Goods();goods.setGname(req.getParameter("gname"));//使用Double包装类把req.getParameter获取到字符串数字 转换为 double类型的数据goods.setPrice(Double.parseDouble(req.getParameter("price")));goods.setMark(req.getParameter("mark"));//执行JDBC的添加操作GoodsDao goodsDao = new GoodsDaoImpl();int i = goodsDao.selectInsert(goods);if (i > 0) {//添加成功req.getRequestDispatcher("selectAllGoods").forward(req, resp);} else {//添加失败req.setAttribute("error_msg", "添加商品出错了!");req.getRequestDispatcher("error.jsp").forward(req, resp);}}
}

 DeleteGoods

1.映射地址

@WebServlet("/del")

package com.chen.httpServlet;import com.chen.Dao.GoodsDao;
import com.chen.Dao.imlp.GoodsDaoImpl;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 java.io.IOException;@WebServlet("/del")
public class DeleteGoods extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {doPost(req, resp);}@Overrideprotected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {int gid = Integer.parseInt(req.getParameter("gid"));//根据id执行数据库的删除GoodsDao goodsDao = new GoodsDaoImpl();int i = goodsDao.selectDelete(gid);if (i>0){//请求转发，查讯所有商品信息（刷新）req.getRequestDispatcher("selectAllGoods").forward(req,resp);}else {req.setAttribute("error_msg","删除出现了问题!");req.getRequestDispatcher("error.jsp").forward(req,resp);}}
}

FindByIdGoods 

1.映射地址

@WebServlet("/findById")

package com.chen.httpServlet;import com.chen.Dao.GoodsDao;
import com.chen.Dao.imlp.GoodsDaoImpl;
import com.chen.bean.Goods;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 java.io.IOException;@WebServlet("/findById")
public class FindByIdGoods extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {doPost(req, resp);}@Overrideprotected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {int gid = Integer.parseInt(req.getParameter("gid"));//根据gid查询商品信息GoodsDao goodsDao = new GoodsDaoImpl();Goods goods = goodsDao.selectById(gid);if (goods!= null){//把数据存储到req域对象中，然后请求转发到页面req.setAttribute("goods",goods);req.getRequestDispatcher("showGoods.jsp").forward(req,resp);}else {//登录失败，跳转到错误页req.setAttribute("error_msg","修改出现异常!");req.getRequestDispatcher("error.jsp").forward(req,resp);}}
}

UpdateGoods

1.映射地址

@WebServlet("/updateGoods")

package com.chen.httpServlet;import com.chen.Dao.GoodsDao;
import com.chen.Dao.UserDao;
import com.chen.Dao.imlp.GoodsDaoImpl;
import com.chen.Dao.imlp.UserDaoImpl;
import com.chen.bean.Goods;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 java.io.IOException;@WebServlet("/updateGoods")
public class UpdateGoods extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {doPost(req, resp);}@Overrideprotected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {req.setCharacterEncoding("utf-8");resp.setCharacterEncoding("utf-8");//获取表单请求的数据，封装到goods对象中Goods goods = new Goods();goods.setGid(Integer.parseInt(req.getParameter("gid")));goods.setGname(req.getParameter("gname"));goods.setPrice(Double.parseDouble(req.getParameter("price")));goods.setMark(req.getParameter("mark"));//执行数据库的修改操作GoodsDao goodsDao = new GoodsDaoImpl();goodsDao.selectUpdate(goods)if (i>0){//请求转发，查讯所有商品信息（刷新）req.getRequestDispatcher("selectAllGoods").forward(req,resp);}else {req.setAttribute("error_msg","修改失败，请重新尝试!");req.getRequestDispatcher("error.jsp").forward(req,resp);}}
}

Seach

@WebServlet("/seach")

package com.chen.httpServlet;import com.chen.Dao.GoodsDao;
import com.chen.Dao.imlp.GoodsDaoImpl;
import com.chen.bean.Goods;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 javax.servlet.http.HttpSession;
import java.io.IOException;
import java.util.List;@WebServlet("/seach")
public class Seach extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {doPost(req, resp);}@Overrideprotected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {req.setCharacterEncoding("utf-8");resp.setCharacterEncoding("utf-8");String keyword = req.getParameter("keyword");//根据关键词执行JDBC的模糊查询GoodsDao goodsDao = new GoodsDaoImpl();List<Goods> goodsList = goodsDao.seach(keyword);//把数据传递到前端页面//通过request获取session对象，该对象可以向前端传递传输数据的容器HttpSession session = req.getSession();//向session 中存入商品信息集合session.setAttribute("goodsList", goodsList);//登录成功，跳转到主页resp.sendRedirect("zhuye.jsp");//指定的跳转页面}
}

到这里代码就结束了，数据库原本的三条数据，正确的账号密码。

如果注册，注册的信息就存在后台的数据库里，如果注册成功就可以登录成功,在后台数据库里添加商品信息，通过session在主页页面中就能看到商品信息。增删改查操作。

不能随意访问网址就能进入注册、添加、主页页面中，所以我们要写个过滤器，防止外来人员直接访问。

第六步 Filter过滤器

1、filter简介

Filter中文意思为过滤器。顾名思义，过滤器可在浏览器以及目标资源之间起到一个过滤的作用。例如:水净化器，可以看成是生活中的一个过滤器，他可以将污水中的杂质过滤，从而使进入的污水变成净水。对于WEB应用来说，过滤器是一个驻留在服务器中的WEB组件，他可以截取客户端和WEB资源之间的请求和响应信息。WEB资源可能包括ServletJSPHTML页面等。

Filter是Tomcat容器内的过滤器，在请求到达容器是先会调用过滤器，再调用我们的servlet或者jsp。

当服务器收到特定的请求后，会先将请求交给过滤器，程序员可以在过滤器中对请求信息进行读取修改等操作，然后将请求信息再发送给目标资源。目标资源作出响应后，服务器会再次将响应转交给过滤器，在过滤器中同样可以对响应信息做一些操作，然后再将响应发送给浏览器。

也就是说过滤器可以在WEB资源收到请求之前，浏览器收到响应之前，对请求和响应信息做一些相应的操作。

在一个WEB应用中可以部署多个过滤器，多个过滤器就组成了一个过滤器链，请求和响应必须在经过多个过滤器后才能到达目标。

过滤器不是必须将请求传送到下一个过滤器(或WEB资源)，也可以自己来处理请求，发送响应。

2、filter的实现

 Filter接口，实现Filter需要实现该接口
1、init()方法用于初始化Filter。

2、doFilter()作用和service()方法类似，是过滤请求和响应的主要方法。

3、destroy0用于在Filter对象被销毁前做一些收尾工作。如:释放资源等

3、filter的生命周期

Filter的生命周期和Servlet类似
构造器:创建Filter实例是调用，Filter实例服务器一旦启动就会被创建
init():实例创建后马上被调用，用来对Filter做一些初始化的操作
doFilter():Filter的主要方法，用来完成过滤器主要功能的方法，每次访问目标资源时都会调用。
destroy():服务器停止时调用，用来释放资源

首先

映射所有

@WebFilter("/*")

实现filter接口

 

 因为要登录（+登录的映射地址），没有账号的要注册（+注册的映射地址），登陆失败跳转错误页面，这些页面都需要放行，直接访问主页会回到登录页面。

具体代码如下：

package com.chen.filter;import com.chen.bean.User;import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.io.IOException;@WebFilter("/*")
public class MyFilter implements Filter {@Overridepublic void init(FilterConfig filterConfig) throws ServletException {System.out.println("初始化..");}@Overridepublic void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {//1.在过滤器中把servletRequest、servletResponse转换为HttpServletRequest、HttpServletResponseHttpServletRequest request = (HttpServletRequest) servletRequest;HttpServletResponse response = (HttpServletResponse) servletResponse;//2.获取请求的资源路径String servletPath = request.getServletPath();//3.获取session储存的用户对象HttpSession session = request.getSession();User user = (User) session.getAttribute("user");//4.1如果请求index.jsp、login.jsp、login、register.jsp、register、error.jsp则放行if (servletPath.equals("/index.jsp") ||servletPath.equals("/login.jsp") ||servletPath.equals("/login") ||servletPath.equals("/register.jsp") ||servletPath.equals("/register") ||servletPath.equals("/error.jsp")){filterChain.doFilter(servletRequest,servletResponse);//放行}else if (user!=null){filterChain.doFilter(servletRequest,servletResponse);//放行}else {response.sendRedirect("login.jsp");}}@Overridepublic void destroy() {System.out.println("销毁..");}
}

项目效果如下：