关于在网页内上传图片新人求教！

我做了一个网页，希望可以使用户上传图片资料，但是按照网上的代码，发现提示上传成功，但我的查看服务器并没有文件，而且上传之后文件也预览不了。求教！！！
我的表单代码：

<form action="upload_file.php" method="post"
enctype="multipart/form-data">
<label for="file">图像文件:</label>
<input type="file" name="file" id="file">
<br>
<input type="submit" name="submit" value="上传图片">
</form>


用的是php来做处理：



<?php
if ((($_FILES["file"]["type"] == "image/gif")
|| ($_FILES["file"]["type"] == "image/jpeg")
|| ($_FILES["file"]["type"] == "image/png")
|| ($_FILES["file"]["type"] == "image/pjpeg"))
&& ($_FILES["file"]["size"] < 2048000))
    {
        if ($_FILES["file"]["error"] > 0)
        {
            echo "Return Code: " . $_FILES["file"]["error"] . "<br/>";
        }
        else
        {
            echo "Upload: " . $_FILES["file"]["name"] . "<br/>";
            echo "Type: " . $_FILES["file"]["type"] . "<br/>";
            echo "Size: " . ($_FILES["file"]["size"] / 1024) . " Kb<br/>";
            echo "Temp file: " . $_FILES["file"]["tmp_name"] . "<br/>";
            $uploaddir="/upload/";
            $filename=$_FILES["file"]["name"];
            $uploadfile=$uploaddir . $filename;
            if (file_exists($filename))
            {
                echo $_FILES["file"]["name"] . " already exists. ";
            }
            else
            {
                move_uploaded_file($_FILES["file"]["tmp_name"], $uploadfile);
                copy($_FILES["file"]["tmp_name"],"$uploadfile");
                echo "<img src='$uploadfile'>";
                if (is_uploaded_file($_FILES["file"]["tmp_name"])==true)
                { //输出预览图片
                    if (file_exists($uploadfile)==true)
                        {echo "Yes!";}
                    else {echo "No!";}
                    echo "<center>您的文件已经上传完毕 上传预览图片：</center><br>
                    <center><img src='$uploadfile'></center>";
                    echo $_FILES["file"]["error"];
                }
                else{
                    "上传失败！";
                }
                echo "Stored in: " . "upload/" . $_FILES["file"]["name"];
            }
        }
    }
else
    {
        echo "无效文件";
    }
?>
测试了一下，结果如下：


但是服务器相应的文件夹下并没有这张图片。