PHP中Curl封装类的定义及使用

<?php
//curl类
class Curl
{
 function Curl(){
  return true;
 }
 function execute($method, $url, $fields='', $userAgent='', $httpHeaders='', $username='', $password=''){
  $ch = Curl::create();
  if(false === $ch){
   return false;
  }
  if(is_string($url) && strlen($url)){
   $ret = curl_setopt($ch, CURLOPT_URL, $url);
  }else{
   return false;
  }
  //是否显示头部信息
  curl_setopt($ch, CURLOPT_HEADER, false);
  //
  curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
  if($username != ''){
   curl_setopt($ch, CURLOPT_USERPWD, $username . ':' . $password);
  }
  $method = strtolower($method);
  if('post' == $method){
   curl_setopt($ch, CURLOPT_POST, true);
   if(is_array($fields)){
    $sets = array();
    foreach ($fields AS $key => $val){
     $sets[] = $key . '=' . urlencode($val);
    }
    $fields = implode('&',$sets);
   }
   curl_setopt($ch, CURLOPT_POSTFIELDS, $fields);
  }else if('put' == $method){
   curl_setopt($ch, CURLOPT_PUT, true);
  }
  //curl_setopt($ch, CURLOPT_PROGRESS, true);
  //curl_setopt($ch, CURLOPT_VERBOSE, true);
  //curl_setopt($ch, CURLOPT_MUTE, false);
  curl_setopt($ch, CURLOPT_TIMEOUT, 10);//设置curl超时秒数
  if(strlen($userAgent)){
   curl_setopt($ch, CURLOPT_USERAGENT, $userAgent);
  }
  if(is_array($httpHeaders)){
   curl_setopt($ch, CURLOPT_HTTPHEADER, $httpHeaders);
  }
  $ret = curl_exec($ch);
  if(curl_errno($ch)){
   curl_close($ch);
   return array(curl_error($ch), curl_errno($ch));
  }else{
   curl_close($ch);
   if(!is_string($ret) || !strlen($ret)){
    return false;
   }
   return $ret;
  }
 }
 function post($url, $fields, $userAgent = '', $httpHeaders = '', $username = '', $password = ''){
  $ret = Curl::execute('POST', $url, $fields, $userAgent, $httpHeaders, $username, $password);
  if(false === $ret){
   return false;
  }
  if(is_array($ret)){
   return false;
  }
  return $ret;
 }
 function get($url, $userAgent = '', $httpHeaders = '', $username = '', $password = ''){
  $ret = Curl::execute('GET', $url, '', $userAgent, $httpHeaders, $username, $password);
  if(false === $ret){
   return false;
  }
  if(is_array($ret)){
   return false;
  }
  return $ret;
 }
 function create(){
  $ch = null;
  if(!function_exists('curl_init')){
   return false;
  }
  $ch = curl_init();
  if(!is_resource($ch)){
   return false;
  }
  return $ch;
 }
}
?>

$curl = new Curl();
$curl->get('http://www.XXX.com/');

$curl = new Curl();
$curl->get('http://www.XXX.com/', 'p=1&time=0');