PHP支持多种格式图片上传(支持jpg、png、gif)

此处一次支持上传2个图片，上传后生成原图和质量较差的图，原图用于保存质量高的图片，质量差的图用于网页显示。
PHP Code

<?php 
include_once("db.php"); 
include_once("dbinfo.php"); 
$connector = new nmdb($host, $username, $password); 
$connector -> select_db($database); 
$work_group = check_input($_POST['work_group']); 
$name = check_input($_POST['name']); 
$tel = check_input($_POST['tel']); 
$id_card = check_input($_POST['id_card']); 
$work_name = check_input($_POST['work_name']); 
$place = check_input($_POST['place']); 
$work1 = check_input($_POST['work1']); 
date_default_timezone_set('PRC'); 
$date = date("Y-m-d H:i:s"); 
$quality = 100; 
$quality2 = 70; 
$quality_png = 9; 
$quality2_png = 7; 
if(isset($_FILES['work1']) && $_FILES['work1']['error']==0) 
{ 
$size = getimagesize($_FILES['work1']['tmp_name']); 
$original = $_FILES['work1']['tmp_name']; 
$type = $_FILES['work1']['type']; 
//echo $type; 
$target_name = date('YmdHis').'_'.preg_replace('`[^a-z0-9-_.]`i','',$_FILES['work1']['name']); 
$work1 = $target_name; 
$target = dirname(__FILE__).'/uploads/'.$target_name; 
switch($type) 
{ 
case "image/jpeg": 
$resultImage = imagecreatefromjpeg($original); 
imagejpeg($resultImage, $target, $quality); 
break; 
case "image/png": 
$resultImage = imagecreatefrompng($original); 
imagepng($resultImage, $target, $quality_png); 
break; 
case "image/gif": 
$resultImage = imagecreatefromgif($original); 
imagegif($resultImage, $target, $quality); 
break; 
default : 
die("不支持此文件类型"); 
exit; 
} 
$work1_small = $target_name; 
$target = dirname(__FILE__).'/uploads/small/'.$target_name; 
switch($type) 
{ 
case "image/jpeg": 
$resultImage = imagecreatefromjpeg($original); 
imagejpeg($resultImage, $target, $quality2); 
break; 
case "image/png": 
$resultImage = imagecreatefrompng($original); 
imagepng($resultImage, $target, $quality2_png); 
break; 
case "image/gif": 
$resultImage = imagecreatefromgif($original); 
imagegif($resultImage, $target, $quality2); 
break; 
default : 
die("不支持此文件类型"); 
exit; 
} 
} 
if(isset($_FILES['work2']) && $_FILES['work2']['error']==0) 
{ 
$size = getimagesize($_FILES['work2']['tmp_name']); 
$original = $_FILES['work2']['tmp_name']; 
$type = $_FILES['work2']['type']; 
$target_name = date('YmdHis').'_'.preg_replace('`[^a-z0-9-_.]`i','',$_FILES['work2']['name']); 
$work2 = $target_name; 
$target = dirname(__FILE__).'/uploads/'.$target_name; 
switch($type) 
{ 
case "image/jpeg": 
$resultImage = imagecreatefromjpeg($original); 
imagejpeg($resultImage, $target, $quality); 
break; 
case "image/png": 
$resultImage = imagecreatefrompng($original); 
imagepng($resultImage, $target, $quality_png); 
break; 
case "image/gif": 
$resultImage = imagecreatefromgif($original); 
imagegif($resultImage, $target, $quality); 
break; 
default : 
die("不支持此文件类型"); 
exit; 
} 
$work2_small = $target_name; 
$target = dirname(__FILE__).'/uploads/small/'.$target_name; 
switch($type) 
{ 
case "image/jpeg": 
$resultImage = imagecreatefromjpeg($original); 
imagejpeg($resultImage, $target, $quality2); 
break; 
case "image/png": 
$resultImage = imagecreatefrompng($original); 
imagepng($resultImage, $target, $quality2_png); 
break; 
case "image/gif": 
$resultImage = imagecreatefromgif($original); 
imagegif($resultImage, $target, $quality2); 
break; 
default : 
die("不支持此文件类型"); 
exit; 
} 
} 
$sql="insert into photo(work_group,name,tel,id_card,work_name,place,work,work_small,date) values('$work_group','$name','$tel','$id_card','$work_name','$place','$work1','$work1_small','$date')"; 
//echo $sql; 
$result = $connector -> query($sql) or die(mysql_error()); 
if($work2 != "" && $work2_small != null) 
{ 
$sql2="insert into photo(work_group,name,tel,id_card,work_name,place,work,work_small,date) values('$work_group','$name','$tel','$id_card','$work_name','$place','$work2','$work2_small','$date')"; 
$result2 = $connector -> query($sql2) or die(mysql_error()); 
} 
$connector -> close($connector); 
$page="../upload.php"; 
echo "<script>alert('上传成功！'); window.location = \"".$page."\";</script>"; 
?>

有些问题需要说明下：
JPEG图像生成的图像的质量的是一个范围从0（最低质量，最小的文件大小）到100（最高质量，最大文件大小）。而ImagePNG生成图像的质量范围从0到9的，传入的这个范围以外的参数则该函数不会工作。
判断上传文件的类型，$type = $_FILES['work1']['type'];。
创建各种格式的图片可以使用这些函数：imagecreatefromjpeg()、imagecreatefrompng()、imagecreatefromgif()。