servlet

package com.davd.dao;

import java.sql.Connection; import java.sql.DriverManager; import java.sql.ResultSet; import java.sql.SQLException; import java.sql.Statement; import java.util.ArrayList; import java.util.List;

import com.davd.Bean.UserBean;

public class UserDao {

public List<UserBean> select(String name)
{
	try {
		Class.forName("com.mysql.jdbc.Driver");
		
		String sql="select * from User where name='"+name+"'";
		System.out.println(sql);
		Connection conn;
		try {
			conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/web?useUnicode=true&characterEncoding=utf-8&useSSL=false","root","root");
			Statement stat=conn.createStatement();
			ResultSet rs = stat.executeQuery(sql);
			ArrayList<UserBean> al = new ArrayList<UserBean>(); 
			while(rs.next())
			{
				UserBean ub = new UserBean();
				ub.setName(rs.getString(2));
				ub.setPassword(rs.getString(3));
				al.add(ub);
			}
			return al;	
			
			
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		
	} catch (ClassNotFoundException e) {
		// TODO Auto-generated catch block
		e.printStackTrace();
	}
	return null;
}
//注册用户方法
public void insertUser(UserBean ub){
	try {
		Class.forName("com.mysql.jdbc.Driver");
		
		String sql="INSERT INTO `user` VALUES ("+0+",'"+ub.getName()+"','"+ub.getPassword()+"');";
		System.out.println(sql);
		Connection conn;
		try {
			conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/web?useUnicode=true&characterEncoding=utf-8&useSSL=false","root","root");
			Statement stat=conn.createStatement();
			stat.execute(sql);
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		
	} catch (ClassNotFoundException e) {
		// TODO Auto-generated catch block
		e.printStackTrace();
	}
		
}

}

import java.io.IOException; import java.util.ArrayList; import java.util.List;

import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse;

import com.davd.Bean.UserBean; import com.davd.dao.UserDao;

public class LoginServlet extends HttpServlet{

public void init()
{
	
}
public void destroy()
{
	
}
public void doPost(HttpServletRequest request,HttpServletResponse response)
{
	//获取请求参数
	String name =request.getParameter("username");
	String password = request.getParameter("password");
	
	//实例化一个dao类，dao类负操作数据库插入
	UserDao ud = new UserDao();
	List<UserBean>  ab =new ArrayList<UserBean>();
	ab = ud.select(name);
	if(ab.size()>0)
	{
		try {
			response.sendRedirect("index.html");
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}else{
		try {
			response.sendRedirect("unregister.html");
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		
	}
	
}

}