java+mysql实现登录和注册功能

<form action="login.do"  method="get">
     <table>
        <tr><td>账号:</td><td><input style="line-height: 28px;" type="text" name="id" /></td></tr>
        <tr><td>密码:</td><td><input style="line-height: 28px;" type="password" name="password" /></td></tr> 
        <tr><td> <a href="register.jsp" rel="external nofollow"  >还没注册？点击注册</a></td><td><input id="login_in" type="submit" value=" 登录 "></td></tr>
        </table>
 </form>

<form name="form1" action="register.do" method="post">
    <table width="200" border="0">
        <tr>
            <td colspan="2">
                <div id="status">注册新用户</div>
            </td>
        <tr>
            <td>*用户名</td>
            <td><input type="text" name="username" size="10" id="username"></td>
        </tr>
        <tr>
            <td>*密码</td>
            <td><input type="password" name="password1" size="10"></td>
        </tr>
        <tr>
            <td>*确认密码</td>
            <td><input type="password" name="password2" size="10"></td>
        </tr>
        <tr>
            <td>Email</td>
            <td><input type="text" name="email" size="10"></td>
        </tr>
        <tr>
            <td colspan="2"><a href="login.jsp" rel="external nofollow" >返回登录页</a> <input
                    type="submit" name="submit" value="提交注册"></td>
        </tr>
    </table>
</form>

create table login(
uname char(15) primary key,
password char(15) not null,
email char(20)
)

import java.sql.*;
public class userlogin {
 
    String drv = "com.mysql.jdbc.Driver";
    String url = "jdbc:mysql://localhost:3306/login";
    String usr = "root";
    String pwd = "***";//自己的密码
 
    public boolean isuserlogin(String id,String password){
        boolean isValid = false;
 
        String sql="select * from ulogin where uname='"+id+"' and password='"+password+"'";
        try{
            Class.forName(drv).newInstance();
            Connection conn = DriverManager.getConnection(url,usr,pwd);
            Statement stm = conn.createStatement();
            ResultSet rs = stm.executeQuery(sql);
 
            if(rs.next()){
                isValid = true;
            }
 
            rs.close();
            stm.close();
            conn.close();
        }catch (Exception e) {
            e.printStackTrace();
            System.out.println(e);
        }
        if(isValid){//判断用户名以及密码是否与设定相符
            return true;
        }
        else return false;
    }
}

import java.sql.*;
public class register {
 
    String drv = "com.mysql.jdbc.Driver";
    String url = "jdbc:mysql://localhost:3306/login";
    String usr = "root";
    String pwd = "***";
 
    public boolean userregister(String id,String password,String email){
 
        boolean b = false;
 
        String sql = "select * from ulogin where uname='"+id+"'";
 
        try{
            Class.forName(drv).newInstance();
            Connection conn = DriverManager.getConnection(url,usr,pwd);
            Statement stm = conn.createStatement();
            ResultSet rs = stm.executeQuery(sql);
 
            if(!rs.next()){
 
                sql = "insert into ulogin(uname,password,email) values('"+id+"','"+password+"','"+email+"')";
                stm.execute(sql);
                b = true;
            }
 
            rs.close();
            stm.close();
            conn.close();
        }catch (Exception e) {
            e.printStackTrace();
            System.out.println(e);
        }
 
        if(b)
        {
            return true;
        }
        else return false;
    }
}

@WebServlet(name = "ServletLogin")
public class ServletLogin extends HttpServlet {
    public void init() throws ServletException {
    }
 
    public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException{
        boolean b=false;
        userlogin MyPOJO=new userlogin();//新建MyPOJO类的对象myPOJO
 
        //根据标示名获取JSP文件中表单所包含的参数
        String id=request.getParameter("id");
        String password=request.getParameter("password");
        String result = "";
 
        b=MyPOJO.isuserlogin(id,password);//使用模型对账号和密码进行验证，返回一个boolean类型的对象
        PrintWriter out = response.getWriter();
        if(b){  //如果验证结果为真，跳转至登录成功页面
            out.println("success");
            result = "success";
            //Cookie
            Cookie username= new Cookie("username",id);
 
            //设置路径，这个路径即该工程下都可以访问该cookie 如果不设置路径，那么只有设置该cookie路径及其子路径可以访问
 
            username.setPath("/");
            username.setMaxAge(60*60);
            response.addCookie(username);
            response.sendRedirect("index.jsp");
        }
        else {  //如果验证结果为假，跳转至登录失败页面
            out.println("fail");
            result = "fail";
            response.sendRedirect("JSP/LoginFailed.jsp" );
        }
        out.write(result);
        out.flush();
        out.close();
        System.out.println(result);
    }

@WebServlet(name = "ServletRegister")
public class ServletRegister extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        boolean b = false;
        register myPOJO=new register();
 
        String id=request.getParameter("username");
        String password=request.getParameter("password1");
        String email = request.getParameter("email");
 
        b=myPOJO.userregister(id,password,email);
 
        if(b){
            response.sendRedirect("login.jsp");
        }
        else{
            response.sendRedirect("register.jsp");
        }
    }
}

<servlet>
        <servlet-name>ServletLogin</servlet-name>
        <servlet-class>service.ServletLogin</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>ServletLogin</servlet-name>
        <url-pattern>/login.do</url-pattern>
    </servlet-mapping>
 
    <servlet>
        <servlet-name>ServletRegister</servlet-name>
        <servlet-class>service.ServletRegister</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>ServletRegister</servlet-name>
        <url-pattern>/register.do</url-pattern>
    </servlet-mapping>

insert into ulogin values('test1','123',null);