利用PHP怎么实现一个图片上传功能

<&#63;php
class more_file_upload{
  const FILE_PATH = '/uploadfile/'; //默认文件上传的目录，请自行修改
  var file_type;
  var file_type_array;
  var file_type_real_array;
  var file_type_string;
  var file_name;
  var file_size;
  var file_tmp_name;
  var file_error;
  var handledate;
  static totalsize = 0;
  function __construct(file_name, file_error, file_size, file_tmp_name, file_type){
    this -> handledate = date('m-d-Y');
    if (!empty(file_name)){
      this -> file_name = file_name;
      this -> file_error = file_error;
      this -> file_size = file_size;
      this -> file_tmp_name = file_tmp_name;
      this -> file_type = file_type;
      this -> file_type_array = array('/', 'image/gif', 'image/jpg', 'image/jpeg', 'image/pjpeg', 'image/png');
      this -> file_type_real_array = array(0.1, 'jpg' => 74707370, 'gif' => 7173, 'bmp' => 6677, 'png' => 807871);
      this -> show_execute_message(this -> file_error, this -> file_name, this -> file_type, this -> file_size);
      }
    }
  function __destruct(){
    this -> file_name = NULL;
    this -> file_error = NULL;
    this -> file_size = NULL;
    this -> file_tmp_name = NULL;
    this -> file_type = NULL;
    self :: totalsize = 0;
    }
  function show_execute_message(smfileerror, smfilename, smfiletype, smfilesize){
    if(smfileerror > 0){
      switch (smfileerror){
      case 1: smfilemessage = '<strong>文件超过服务器的约定大小！</strong>';
        break;
      case 2: smfilemessage = '<strong>文件超过指定的文件大小！</strong>';
        break;
      case 3: smfilemessage = '<strong>文件只上传了部分！</strong>';
        break;
      case 4: echo "this->file_name " . '文件上传失败！<br/>';
        break;
        }
      self :: __destruct();
      }else{
      smfiletypeflag = array_search(smfiletype, this -> file_type_array);
      // 进行真实格式验证
      if(smfiletypeflag != false){
        file = fopen(this -> file_tmp_name, "rb");
        bin = fread(file, 10);
        fclose(file);
        strInfo = @unpack("c10chars", bin);
        typeCode = intval(strInfo['chars1'] . strInfo['chars2']);
        smfiletypeflag = array_search(typeCode, this -> file_type_real_array);
        if(smfiletypeflag == false){ // 判断是否是png图片
          typeCode = intval(strInfo['chars2'] . strInfo['chars3'] . strInfo['chars4']);
          smfiletypeflag = array_search(typeCode, this -> file_type_real_array);
          if(smfiletypeflag == false){ // 判断是否是jpg图片
            $typeCode = intval(strInfo['chars7'] . strInfo['chars8'] . strInfo['chars9'] . strInfo['chars10']);
            smfiletypeflag = array_search(typeCode, this -> file_type_real_array);
            }
          }
        }
      if($smfiletypeflag == false){
        $smfilemessage = '<strong>文件类型不对，请核实！</strong>';
        self :: __destruct();
        }else{
        $resflag = $this -> move_file($this -> file_tmp_name, this -> file_name);
        if (resflag == 1){
          $smfilemessage = '文件上传成功！';
          self :: totalsize += intval($smfilesize);
          self :: __destruct();
          }else{
          $smfilemessage = '<strong>文件上传失败！</strong>';
          self :: __destruct();
          }
        }
      }
    $smfilesizeformat = $this -> size_BKM(smfilesize);
    echo '<tr>
<td align="left" >' . smfilename . '</td>
<td align="center" >' . smfiletype . '</td>
<td align="center" >' . smfilesizeformat . '</td>
<td align="center" >' . smfilemessage . '</td>
</tr>';
    }
  function move_file(mvfiletmp, mvfilename){ // 移动文件
    mvfilenamearr = explode('.', basename(mvfilename));
    mvfilenamearr[0] = this -> rand_string();
    mvfilename = implode('.', mvfilenamearr);
    if (is_uploaded_file(mvfiletmp)){
      uploadfile = self :: FILE_PATH . "mvfilename";
      result = move_uploaded_file(mvfiletmp, uploadfile);
      return result;
      }
    }
  function rand_string(){
    string = md5(uniqid(rand() . microtime()));
    return string;
    }
  function size_BKM(size){ // B/KB/MB单位转换
    if(size < 1024)
    {
      size_BKM = (string)size . " B";
      }
    elseif(size < (1024 * 1024))
      {
      size_BKM = number_format((double)(size / 1024), 1) . " KB";
      }else
      {
      size_BKM = number_format((double)(size / (1024 * 1024)), 1) . " MB";
      }
    return size_BKM;
    }
  }
&#63;>