JAVA-EE简单实例——Servlet

首先实现前后端交互有三种方式：

前后交互有3种实现： J2EE, SSM 和 Springboot。

本文就J2EE的方式来实例化。

项目效果：淘宝登录界面、购物车界面（主要实现前端、Servlet、数据库三者交互）。

项目结构图：

建好项目后导入需要用到的jar包放入WEB-INF下的lib包里。

首先，我们写一个登录界面效果如图（忽略我前端水平。23333）

user类

package bean;

public class User {
	public int id;
	public String name;
	public String password;
	
	
	public User() {
		super();
	}
	public User(int id, String name, String password) {
		super();
		this.id = id;
		this.name = name;
		this.password = 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;
	}
	
}

userDAO：

package dao;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

import bean.User;
import jdbc.Jdbc;

public class UserDAO {
	//参数
	User user=new User();
	//获取jdbc
	Jdbc jdbc=new Jdbc();
	Connection connection=jdbc.getConnection();	
	
	//登录验证--账户正确否
	public User getUser(String name,String password) {
		try {									
			String sql="select * from user where name = ? and password=?";		
			PreparedStatement ps=connection.prepareStatement(sql);
			ps.setString(1, name);
			ps.setString(2, password);
			ResultSet rs=ps.executeQuery();
			while(rs.next()) {
				user.setId(rs.getInt(1));
				user.setName(rs.getString(2));
				user.setPassword(rs.getString(3));
			}			
			ps.close();
			rs.close();
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		return user;
		
	}
	
}

jdbc：

package jdbc;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;

public class Jdbc {
	//全局变量
	Connection connection=null;
	
	public Connection getConnection() {		
		//jdbc
		try {
			Class.forName("com.mysql.jdbc.Driver");			
			String user ="root";
			String password="admin";
			String url="jdbc:mysql://127.0.0.1:3306/cart?characterEncoding=UTF-8";		
			connection=DriverManager.getConnection(url,user,password);
			if (connection != null) {
				System.out.println("conn: "+connection);
			}
		} catch (ClassNotFoundException e) {
			// TODO Auto-generated catch block	
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}	
		return connection;
	}
       //测试
	public static void main(String[] args) {
		Jdbc jdbc=new Jdbc();
		jdbc.getConnection();
	}

}

LoginServlet：

package servlet;

import java.io.IOException;
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 bean.User;
import dao.UserDAO;

/**
 * Servlet implementation class LoginServlet
 */
@WebServlet("/LoginServlet")
public class LoginServlet extends HttpServlet {
	//参数
	UserDAO userDAO =new UserDAO();
	private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServle