要进行购买，还需要用户处于登陆状态，因为后续生成的订单，需要挂在某个用户的名下。
步骤1:SQL
步骤2:User
步骤3:UserDAO
步骤4:login.jsp
步骤5:UserLoginServlet
步骤6:配置web.xml
步骤7:listProduct.jsp
步骤8:测试
步骤 1 : SQL
与Product模块类似的，不提供完整的用户CRUD(增 删 改 查) 也是通过SQL准备User数据。
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create table user(
id int,
name varchar(50),
password varchar(50)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
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insert into user values(1,'tom','123');
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步骤 2 : User
User 类
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package bean;
public class User {
private int id;
private String name;
private String password;
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 getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
}
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步骤 3 : UserDAO
根据name和password查询表user,如果有数据就表示账号密码正确
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package dao;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import bean.User;
public class UserDAO {
public static void main(String[] args) {
System.out.println(new UserDAO().getUser("tom", "123").getId());
}
public User getUser(String name, String password) {
User result = null;
try {
Class.forName("com.mysql.jdbc.Driver");
Connection c = DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/cart?characterEncoding=UTF-8",
"root", "admin");
String sql = "select * from user where name = ? and password = ?";
PreparedStatement ps = c.prepareStatement(sql);
ps.setString(1, name);
ps.setString(2, password);
ResultSet rs = ps.executeQuery();
if (rs.next()){
result = new User();
result.setId(rs.getInt(1));
result.setPassword(password);
result.setName(name);
}
ps.close();
c.close();
} catch (ClassNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return result;
}
}
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步骤 4 : login.jsp
登陆页面
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<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8" import="java.util.*"%>
<!DOCTYPE html>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<form action="login" method="post">
账号： <input type="text" name="name"> <br>
密码： <input type="password" name="password"> <br>
<input type="submit" value="登录">
</form>
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步骤 5 : UserLoginServlet
登陆Servlet， 通过name和password获取user对象
如果对象不为空，就表示账号密码正确，跳转到产品显示界面 /listProduct
如果对象为空，就跳转到登陆界面，重新登陆
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package servlet;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import bean.User;
import dao.UserDAO;
public class UserLoginServlet extends HttpServlet {
protected void service(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
String name = request.getParameter("name");
String password = request.getParameter("password");
User user = new UserDAO().getUser(name, password);
if (null != user) {
request.getSession().setAttribute("user", user);
response.sendRedirect("/listProduct");
} else
response.sendRedirect("/login.jsp");
}
}
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步骤 6 : 配置web.xml
在web.xml中为路径/login加上相关配置
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<?xml version="1.0" encoding="UTF-8"?>
<web-app>
<servlet>
<servlet-name>ProductListServlet</servlet-name>
<servlet-class>servlet.ProductListServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>ProductListServlet</servlet-name>
<url-pattern>/listProduct</url-pattern>
</servlet-mapping>
<servlet>
<servlet-name>LoginServlet</servlet-name>
<servlet-class>servlet.UserLoginServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>LoginServlet</servlet-name>
<url-pattern>/login</url-pattern>
</servlet-mapping>
</web-app>
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步骤 7 : listProduct.jsp
修改listProduct.jsp，如果用户登陆了，就显示用户的名字
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<c:if test="${!empty user}">
<div align="center">
当前用户: ${user.name}
</div>
</c:if>
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<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8" import="java.util.*" isELIgnored="false"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
<c:if test="${!empty user}">
<div align="center">
当前用户: ${user.name}
</div>
</c:if>
<table align='center' border='1' cellspacing='0'>
<tr>
<td>id</td>
<td>名称</td>
<td>价格</td>
<td>购买</td>
</tr>
<c:forEach items="${products}" var="product" varStatus="st">
<tr>
<td>${product.id}</td>
<td>${product.name}</td>
<td>${product.price}</td>
<td>
<form action="addOrderItem" method="post">
数量<input type="text" value="1" name="num">
<input type="hidden" name="pid" value="${product.id}">
<input type="submit" value="购买">
</form>
</tr>
</c:forEach>
</table>
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步骤 8 : 测试
访问登陆页面，输入账号密码： tom: 123
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http://127.0.0.1/login.jsp
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