文档介绍：ThinkPHP实例 用户注册登录留言
PHP框架ThinkPHP一个实例，该实例包含用户注册、登录和留言等功效，最值得大家注意是在存在用户模型情况下实例化一个用户类时候使用D方法来实现。
<?php
class UserAction extends Action{
public function add(){
$user = D("user");
$user->create();
$result = $user->add();
if($result){
$this->assign("jumpUrl","__APP__/index/index");
$this->success('注册成功！');
}else{
//echo $user->getError();
$this->assign("jumpUrl","__APP__/user/register");
$this->error($user->getError());
}
}
public function register(){
$this->display();
}
public function login(){
$this->display();
}
public function checklogin(){
$username = $_POST['username'];
$passwd = $_POST['passwd'];
$user = D("user");
//$User->where('id=8')->find();这里where 语句要注意一下，假如是其它字段话后面一定要有单引号
$userinfo = $user->where("username ='$username'")->find();
if(!empty($userinfo)){
if($userinfo['passwd'] == $passwd){
Cookie::set('userid',$userinfo['id'],time()+3600*24);
Cookie::set('username',$username,time()+3600*24);
Cookie::set('lastlogintime',time(),time()+3600*24);
$this->assign("jumpUrl","__APP__/index/index");
$this->success('登陆成功！');
}else{
$this->assign("jumpUrl","__APP__/user/login");
$this->error('
密码犯错，请重新输入！');
}
}else{
$this->assign("jumpUrl","__APP__/user/login");
$this->error('用户名不存在！');
}
}
public function loginout(){
Cookie::delete('username');
Cookie::delete('lastlogintime');
$this->assign("jumpUrl","