登陆注册的简单实现

（一）搭建简单的登陆页面

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>用户登录</title>
</head>
<body>
    <form action="login.do" method="post">
        用户名:<input type="text" name="name" /><br/>
        密 &nbsp;码 :<input type="text" name="password" /><br />      
        <input type="submit" value="登录"  />
        <a href="register.jsp">没有账号，去注册</a>
    </form> 
    <font color="red" size="2"> ${mes }</font>
</body>
</html>

（二）将工程结构进行完善

这里写图片描述

（三）编写User类与DBCPUtils类以及配置

1.User类

public class User {
    private int id;
    private String name;
    private String password;
    public User() {

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

    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;
    }
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    @Override
    public String toString() {
        return "User [id=" + id + ", name=" + name + ", password=" + password + "]";
    }   
}

2.DBCPUtils数据库连接池

import java.io.IOException;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.SQLException;
import java.util.Properties;

import javax.sql.DataSource;

import org.apache.commons.dbcp.BasicDataSource;
import org.apache.commons.dbcp.BasicDataSourceFactory;

public class DBCPUtils {
    private static DataSource ds=null;
    static {
        try {
        InputStream is=DBCPUtils.class.getClassLoader().getResourceAsStream("dbcpconfig.properties");
        Properties pro=new Properties();
            pro.load(is);
            ds=BasicDataSourceFactory.createDataSource(pro);
        } catch ( Exception e) {
            e.printStackTrace();
        }
    }
    public static DataSource getDataSource() {
        return ds;
    }
    public static Connection getConnection() {
        try {
            return ds.getConnection();
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return null;
    }
}

3.连接数据库
在src目录下新建dbcpconfig.properties文件
配置：
#\u8FDE\u63A5\u8BBE\u7F6E
driverClassName=com.mysql.jdbc.Driver
url=jdbc:mysql://localhost:3306/myjdbc
username=root
password=root
#\u521D\u59CB\u5316\u8FDE\u63A5
initialSize=5
#\u6700\u5927\u8FDE\u63A5\u6570\u91CF
maxActive=10
#\u6700\u5927\u7A7A\u95F2\u8FDE\u63A5
maxIdle=10

（四）写LoginServlet类

import java.io.IOException;
import java.sql.SQLException;
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 dao.UserDao;

@WebServlet("/login.do")
public class LoginServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

    public LoginServlet() {
        super();
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        doPost(request, response);

    }

    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        request.setCharacterEncoding("utf-8");
        response.setCharacterEncoding("text/html;charset=utf-8");
        String name = request.getParameter("name");
        String password = request.getParameter("password");
        if(name.equals("")||password.equals("")){
            HttpSession session = request.getSession();
            request.getSession().setAttribute("mes", "用户名和密码不能为空");
            request.getRequestDispatcher("index.jsp").forward(request, response);
            return;
        }
        UserDao dao = new UserDao();
        try {
            boolean flag = dao.login(name, password);
            if (flag == true) {
                HttpSession session = request.getSession();
                session.setAttribute("isLogin", "登录成功");
                response.sendRedirect("success.jsp");
            } else {
                request.getSession().setAttribute("mes", "登录失败,用户名或密码错误！");
                response.sendRedirect("index.jsp");
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

（五）在UserDao类下实现login()方法并测试

1.设计并实现login()方法

public boolean login(String name, String password) throws Exception {
        QueryRunner runner = new QueryRunner(DBCPUtils.getDataSource());
        String sql = "select * from tb_user where name=? and password=?";
        User user = runner.query(sql, new BeanHandler<User>(User.class), name, password);
        if (user != null) {
            return true;
        } else {
            return false;
        }
    }

2.测试
这里写图片描述

（六）完成注册页面

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>用户注册</title>
</head>
<body>
<form action="reg.do" method="post">
 &nbsp;用 户 名&nbsp;:<input type="text" name="name"/><br/>
 &nbsp; 密 &nbsp;&nbsp;码 &nbsp;:<input type="text" name="password"/><br/>
确认密码:<input type="text" name="password2"/><br/>
<input type="submit" value="注册"/>
</form>
<font color="red" size="2"> ${mess }</font>
</body>
</html>

（七）创建并完成RegisterServlet类

import java.io.IOException;
import java.io.PrintWriter;
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 dao.UserDao;
import domain.User;

@WebServlet("/reg.do")
public class RegistServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

    public RegistServlet() {
        super();
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) 
            throws ServletException, IOException {
        doPost(request,response);
    }

    protected void doPost(HttpServletRequest request, HttpServletResponse response) 
            throws ServletException, IOException {
        request.setCharacterEncoding("utf-8");
        response.setContentType("text/html;charset=utf-8");
        PrintWriter out=response.getWriter();
        String name=request.getParameter("name");
        String password=request.getParameter("password");
        String password2=request.getParameter("password2");
        User user=new User(name,password);
        HttpSession session=request.getSession();
        if(name.equals("")||password.equals("")){
            request.getSession().setAttribute("mess", "用户名和密码不能为空");
            request.getRequestDispatcher("register.jsp").forward(request, response);
            return;
        }
        if(!password.equals(password2)){
            request.getSession().setAttribute("mess", "两次输入的密码不同");
            request.getRequestDispatcher("register.jsp").forward(request, response);
            return;
        }
        UserDao dao=new UserDao();
        if(dao.select(name)==true) {
            request.setAttribute("mess", "用户名已存在！");
            request.getRequestDispatcher("register.jsp").forward(request, response);
            return;
        }
        if(dao.addUser(user)>=1) {
            //根据结果判断  给出不同的view页面
            request.getRequestDispatcher("regSuccess.jsp").forward(request, response);
        }else {
            request.getSession().setAttribute("mess", "注册失败,请重试！！！");
            request.getRequestDispatcher("register.jsp").forward(request, response);
        }
    }
}

（八）完善UserDao类中的select()方法与addUser()方法，然后测试
1.select()方法

public boolean select(String name) {
        String sql = "select * from tb_user where name=?";
        QueryRunner run = new QueryRunner(DBCPUtils.getDataSource());
        User u=null;
        try {
            u=run.query(sql,new BeanHandler<User>(User.class),name);
            if (u!=null&&u.getName().equals(name)) {
                return true;
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        return false;

2.addUser()方法

public int addUser(User user) {
        int result = 0;
        String sql = "insert into tb_user(name,password)values(?,?)";
        QueryRunner run = new QueryRunner(DBCPUtils.getDataSource());
        try {
            result = run.update(sql, user.getName(), user.getPassword());
        } catch (Exception e) {
            e.printStackTrace();
        }
        return result;
    }

3.测试
这里写图片描述

（九）应该注意的问题
1.需要传输数据时使用post请求相对于get请求更安全
2.不登录时,可以通过输入url地址直接访问登录成功界面,所以，登录成功界面也需要验证
在登录成功页面添加下面代码可以完成验证。

<%
   if(session.getAttribute("isLogin")==null){ 
      response.sendRedirect("fail.jsp");
       return;
   }
%>

输入url地址直接访问时，会出现如下界面
这里写图片描述