本文实例讲解了PHP图片上传并压缩的实现方法，分享给大家供大家参考，具体内容如下

使用到三个文件

• connect.php：连接数据库
• test_upload.php：执行SQL语句
• upload_img.php：上传图片并压缩
  

三个文件代码如下：
连接数据库：connect.php

<?php$db_host = '';$db_user = '';$db_psw = '';$db_name = '';$db_port = '';$sqlconn=new mysqli($db_host,$db_user,$db_psw,$db_name);$q="set names utf8;";$result=$sqlconn->query($q);if (mysqli_connect_errno()) { printf("Connect failed: %s\n", mysqli_connect_error()); exit();}?>

执行SQL语句：test_upload.php

<?phprequire ("connect.php");require ("upload_img.php");$real_img=$uploadfile; $small_img=$uploadfile_resize;$insert_sql = "insert into img (real_img,small_img) values (?,?)";$result = $sqlconn -> prepare($insert_sql);$result -> bind_param("ss", $real_img,$small_img);$result -> execute();?>

上传图片并压缩：upload_img.php

<?php //设置文件保存目录$uploaddir = "upfiles/"; //设置允许上传文件的类型$type=array("jpg","gif","bmp","jpeg","png"); //获取文件后缀名函数 function fileext($filename) { return substr(strrchr($filename, '.'), 1); } //生成随机文件名函数 function random($length) { $hash = 'CR-'; $chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789abcdefghijklmnopqrstuvwxyz'; $max = strlen($chars) - 1; mt_srand((double)microtime() * 1000000); for($i = 0; $i < $length; $i++) { $hash .= $chars[mt_rand(0, $max)]; } return $hash; } $a=strtolower(fileext($_FILES['filename']['name'])); //判断文件类型 if(!in_array(strtolower(fileext($_FILES['filename']['name'])),$type)) { $text=implode(",",$type); $ret_code=3;//文件类型错误 $page_result=$text; $retArray = array('ret_code' => $ret_code,'page_result'=>$page_result); $retJson = json_encode($retArray); echo $retJson; return;} //生成目标文件的文件名 else{ $filename=explode(".",$_FILES['filename']['name']); do { $filename[0]=random(10); //设置随机数长度 $name=implode(".",$filename); //$name1=$name.".Mcncc"; $uploadfile=$uploaddir.$name; } while(file_exists($uploadfile)); if (move_uploaded_file($_FILES['filename']['tmp_name'],$uploadfile)) { if(is_uploaded_file($_FILES['filename']['tmp_name'])) { $ret_code=1;//上传失败 } else {//上传成功 $ret_code=0; } } $retArray = array('ret_code' => $ret_code);$retJson = json_encode($retArray);echo $retJson;}//压缩图片$uploaddir_resize="upfiles_resize/";$uploadfile_resize=$uploaddir_resize.$name;//$pic_width_max=120;//$pic_height_max=90;//以上与下面段注释可以联合使用，可以使图片根据计算出来的比例压缩$file_type=$_FILES["filename"]['type'];function ResizeImage($uploadfile,$maxwidth,$maxheight,$name){ //取得当前图片大小 $width = imagesx($uploadfile); $height = imagesy($uploadfile); $i=0.5; //生成缩略图的大小 if(($width > $maxwidth) || ($height > $maxheight)) { /* $widthratio = $maxwidth/$width; $heightratio = $maxheight/$height; if($widthratio < $heightratio) { $ratio = $widthratio; } else { $ratio = $heightratio; } $newwidth = $width * $ratio; $newheight = $height * $ratio; */ $newwidth = $width * $i; $newheight = $height * $i; if(function_exists("imagecopyresampled")) { $uploaddir_resize = imagecreatetruecolor($newwidth, $newheight); imagecopyresampled($uploaddir_resize, $uploadfile, 0, 0, 0, 0, $newwidth, $newheight, $width, $height); } else { $uploaddir_resize = imagecreate($newwidth, $newheight); imagecopyresized($uploaddir_resize, $uploadfile, 0, 0, 0, 0, $newwidth, $newheight, $width, $height); } ImageJpeg ($uploaddir_resize,$name); ImageDestroy ($uploaddir_resize); } else { ImageJpeg ($uploadfile,$name); }}if($_FILES["filename"]['size']){ if($file_type == "image/pjpeg"||$file_type == "image/jpg"|$file_type == "image/jpeg") { //$im = imagecreatefromjpeg($_FILES[$upload_input_name]['tmp_name']); $im = imagecreatefromjpeg($uploadfile); } elseif($file_type == "image/x-png") { //$im = imagecreatefrompng($_FILES[$upload_input_name]['tmp_name']); $im = imagecreatefromjpeg($uploadfile); } elseif($file_type == "image/gif") { //$im = imagecreatefromgif($_FILES[$upload_input_name]['tmp_name']); $im = imagecreatefromjpeg($uploadfile); } else//默认jpg { $im = imagecreatefromjpeg($uploadfile); } if($im) { ResizeImage($im,$pic_width_max,$pic_height_max,$uploadfile_resize); ImageDestroy ($im); }} ?>

请按照现实情况更改connect.php，test_upload.php中对应的信息。

以上就是PHP实现图片上传并压缩的方法，希望对大家的学习php程序设计有所帮助