1.类文件名为：upclass.php

<?php
class upclass {
    public $previewsize = 0.125 ; //预览图片比例
    public $preview = 0; //是否生成预览，是为1，否为0
    public $datetime; //随机数
    public $ph_name; //上传图片文件名
    public $ph_tmp_name; //图片临时文件名
    public $ph_path = "./userimg/"; //上传文件存放路径
    public $ph_type; //图片类型
    public $ph_size; //图片大小
    public $imgsize; //上传图片尺寸，用于判断显示比例
    public $al_ph_type = array('image/jpg', 'image/jpeg', 'image/png', 'image/pjpeg', 'image/gif', 'image/bmp', 'image/x-png'); //允许上传图片类型
    public $al_ph_size = 1000000; //允许上传文件大小
    function __construct() {
        $this->set_datatime();
    } 
    function set_datatime() {
        $this->datetime = date("YmdHis");
    } 
    // 获取文件类型
    function get_ph_type($phtype) {
        $this->ph_type = $phtype;
    } 
    // 获取文件大小
    function get_ph_size($phsize) {
        $this->ph_size = $phsize . "<br>";
    } 
    // 获取上传临时文件名
    function get_ph_tmpname($tmp_name) {
        $this->ph_tmp_name = $tmp_name;
        $this->imgsize = getimagesize($tmp_name);
    } 
    // 获取原文件名
    function get_ph_name($phname) {
        $this->ph_name = $this->ph_path . $this->datetime . strrchr($phname, "."); //strrchr获取文件的点最后一次出现的位置
        // $this->ph_name=$this->datetime.strrchr($phname,"."); //strrchr获取文件的点最后一次出现的位置
        return $this->ph_name;
    } 
    // 判断上传文件存放目录
    function check_path() {
        if (!file_exists($this->ph_path)) {
            mkdir($this->ph_path);
        } 
    } 
    // 判断上传文件是否超过允许大小
    function check_size() {
        if ($this->ph_size > $this->al_ph_size) {
            $this->showerror("上传图片超过2000KB");
        } 
    } 
    // 判断文件类型
    function check_type() {
        if (!in_array($this->ph_type, $this->al_ph_type)) {
            $this->showerror("上传图片类型错误");
        } 
    } 
    // 上传图片
    function up_photo() {
        if (!move_uploaded_file($this->ph_tmp_name, $this->ph_name)) {
            $this->showerror("上传文件出错");
        } 
    } 
    // 图片预览
    function showphoto() {
        if ($this->preview == 1) {
            if ($this->imgsize[0] > 2000) {
                $this->imgsize[0] = $this->imgsize[0] * $this->previewsize;
                $this->imgsize[1] = $this->imgsize[1] * $this->previewsize;
            } 
            echo("<img src={$this->ph_name} width={$this->imgsize['0']} height={$this->imgsize['1']}>");
		} 
	} 
	// 错误提示
	function showerror($errorstr) {
		echo "<script language='javascript'>alert('$errorstr');location='javascript:history.go(-1)';</script>";
		exit();
	} 
	function save() {
		$this->check_path();
		$this->check_size();
		$this->check_type();
		$this->up_photo();
		$this->showphoto();
	} 
} 
?>

<form action="upphoto.php" method="post" enctype="multipart/form-data">
图片来源：<input type="file" name="photo" id="photo">
<input type="submit" name="submit" value="上传">
</form>	

<?php
header("Content-Type:text/html; charset=utf-8"); 
// 类的实例化：
include("upclass.php"); //类的文件名是upoop.php
$up = new upclass();
$submit = $_POST['submit'];
if ($submit == "上传") {
    $up->get_ph_tmpname($_FILES['photo']['tmp_name']);
    $up->get_ph_type($_FILES['photo']['type']);
    $up->get_ph_size($_FILES['photo']['size']);
    $up->get_ph_name($_FILES['photo']['name']);
    $up->save();
} 
?>
<?php
$images = $up->get_ph_name($_FILES['photo']['name']);
echo "<img src=" . $images . ">";
?>