文件上传和下载实例源码

<?php
/**
 * gdbasic.php
 * description gd基础类
 */

namespace test\lib;


class gdbasic
{
    protected static $_check =false;

    //检查服务器环境中gd库
    public static function check()
    {
        //当静态变量不为false
        if(static::$_check)
        {
            return true;
        }

        //检查gd库是否加载
        if(!function_exists("gd_info"))
        {
            throw new \exception('gd is not exists');
        }

        //检查gd库版本
        $version = '';
        $info = gd_info();
        if(preg_match("/\\d+\\.\\d+(?:\\.\\d+)?/", $info["gd version"], $matches))
        {
            $version = $matches[0];
        }

        //当gd库版本小于2.0.1
        if(!version_compare($version,'2.0.1','>='))
        {
            throw new \exception("gd requires gd version '2.0.1' or greater, you have " . $version);
        }

        self::$_check = true;
        return self::$_check;
    }
}

<?php
/**
 * image.php
 * description 图像类
 */

namespace test\lib;

require_once 'gdbasic.php';

class image extends gdbasic
{
    protected $_width;
    protected $_height;
    protected $_im;
    protected $_type;
    protected $_mime;
    protected $_real_path;

    
    public function __construct($file)
    {
        //检查gd库
        self::check();
        $imageinfo = $this->createimagebyfile($file);
        $this->_width = $imageinfo['width'];
        $this->_height = $imageinfo['height'];
        $this->_im = $imageinfo['im'];
        $this->_type = $imageinfo['type'];
        $this->_real_path = $imageinfo['real_path'];
        $this->_mime = $imageinfo['mime'];
    }


    /**
     * 根据文件创建图像
     * @param $file
     * @return array
     * @throws \exception
     */
    public function createimagebyfile($file)
    {
        //检查文件是否存在
        if(!file_exists($file))
        {
            throw new \exception('file is not exits');
        }

        //获取图像信息
        $imageinfo = getimagesize($file);
        $realpath = realpath($file);
        if(!$imageinfo)
        {
            throw new \exception('file is not image file');
        }

        switch($imageinfo[2])
        {
            case imagetype_gif:
                $im = imagecreatefromgif($file);
                break;
            case imagetype_jpeg:
                $im = imagecreatefromjpeg($file);
                break;
            case imagetype_png:
                $im = imagecreatefrompng($file);
                break;
            default:
                throw  new \exception('image file must be png,jpeg,gif');
        }

        return array(
            'width'     => $imageinfo[0],
            'height'    => $imageinfo[1],
            'type'      => $imageinfo[2],
            'mime'      => $imageinfo['mime'],
            'im'        => $im,
            'real_path' => $realpath,
        );

    }

    /**
     * 缩略图
     * @param  int $width 缩略图高度
     * @param  int $height 缩略图宽度
     * @return $this
     * @throws \exception
     */
    public function resize($width, $height)
    {
        if(!is_numeric($width) || !is_numeric($height))
        {
            throw new \exception('image width or height must be number');
        }
        //根据传参的宽高获取最终图像的宽高
        $srcw = $this->_width; 
        $srch = $this->_height;

        if($width <= 0 || $height <= 0)
        {
            $desw = $srcw;//缩略图高度
            $desh = $srch;//缩略图宽度
        }
        else
        {
            $srcp = $srcw / $srch;//宽高比
            $desp = $width / $height; 

            if($width > $srcw)
            {
                if($height > $srch)
                {
                    $desw = $srcw;
                    $desh = $srch;
                }
                else
                {
                    $desh = $height;
                    $desw = round($desh * $srcp);
                }
            }
            else
            {
                if($desp > $srcp)
                {
                    $desw = $width;
                    $desh = round($desw / $srcp);
                }
                else
                {
                    $desh = $height;
                    $desw = round($desh * $srcp);
                }
            }
        }

        //php版本小于5.5
        if(version_compare(php_version, '5.5.0', '<'))
        {
            $desim = imagecreatetruecolor($desw, $desh);
            if(imagecopyresampled($desim, $this->_im, 0, 0, 0, 0, $desw, $desh, $srcw, $srch))
            {
                imagedestroy($this->_im);
                $this->_im = $desim;
                $this->_width = imagesx($this->_im);
                $this->_height = imagesy($this->_im);
            }
        }
        else
        {
            if($desim = imagescale($this->_im, $desw, $desh))
            {
                $this->_im = $desim;
                $this->_width = imagesx($this->_im);
                $this->_height = imagesy($this->_im);
            }

        }

        return $this;
    }


    /**
     * 根据百分比生成缩略图
     * @param int $percent 1-100
     * @return image
     * @throws \exception
     */
    public function resizebypercent($percent)
    {
        if(intval($percent) <= 0)
        {
            throw new \exception('percent must be gt 0');
        }

        $percent = intval($percent) > 100 ? 100 : intval($percent);

        $percent = $percent / 100;

        $desw = $this->_width * $percent;
        $desh = $this->_height * $percent;
        return $this->resize($desw, $desh);
    }


    /**
     * 图像旋转
     * @param $degree
     * @return $this
     */
    public function rotate($degree)
    {
        $degree = 360 - intval($degree);
        $back = imagecolorallocatealpha($this->_im,0,0,0,127);
        $im = imagerotate($this->_im,$degree,$back,1);
        imagesavealpha($im,true);
        imagedestroy($this->_im);
        $this->_im = $im;
        $this->_width = imagesx($this->_im);
        $this->_height = imagesy($this->_im);
        return $this;
    }


    /**
     * 生成水印
     * @param file $water 水印图片
     * @param int $pct   透明度
     * @return $this
     */
    public function watermask($water ='',$pct = 60 )
    {
        //根据水印图像文件生成图像资源
        $waterinfo = $this->createimagebyfile($water);
        imagecopymerge();
        //销毁$this->_im
        $this->_im = $waterinfo['im'];
        $this->_width = imagesx($this->_im);
        $this->_height = imagesy($this->_im);
        return $this;

    }



    /**
     * 图片输出
     * @return bool
     */
    public function show()
    {
        header('content-type:' . $this->_mime);
        if($this->_type == 1)
        {
            imagegif($this->_im);
            return true;
        }

        if($this->_type == 2)
        {
            imagejpeg($this->_im, null, 80);
            return true;
        }

        if($this->_type == 3)
        {
            imagepng($this->_im);
            return true;
        }
    }

    /**
     * 保存图像文件
     * @param $file
     * @param null $quality
     * @return bool
     * @throws \exception
     */
    public function save($file, $quality = null)
    {
        //获取保存目的文件的扩展名
        $ext = pathinfo($file, pathinfo_extension);
        $ext = strtolower($ext);
        if(!$ext || !in_array($ext, array('jpg', 'jpeg', 'gif', 'png')))
        {
            throw new \exception('image save file must be jpg ,png,gif');
        }

        if($ext === 'gif')
        {
            imagegif($this->_im, $file);
            return true;
        }
        if($ext === 'jpeg' || $ext === 'jpg')
        {
            if($quality > 0)
            {
                if($quality < 1)
                {
                    $quality = 1;
                }
                if($quality > 100)
                {
                    $quality = 100;
                }

                imagejpeg($this->_im, $file, $quality);
            }
            else
            {
                imagejpeg($this->_im, $file);
            }
            return true;
        }

        if($ext === 'png')
        {
            imagepng($this->_im, $file);
            return true;
        }

    }
}

let $ = new class {

    constructor()
    {
        this.xhr = new xmlhttprequest();
        this.xhr.onreadystatechange = () => {
            if (this.xhr.readystate == 4 && this.xhr.status == 200) {
                // process response text
                let response = this.xhr.responsetext;
                if (this.type == "json") {
                    response = json.parse(response);
                }
                this.callback(response);
            }
        }
    }

    get(url, parameters, callback, type = "text")
    {
        // url = test.php?username=zhangsan&age=20
        // parameters = {"username": "zhangsan", "age": 20}
        let data = this.parseparameters(parameters);
        if (data.length > 0) {
            url += "?" + data;
        }
        this.type = type;
        this.callback = callback;
        this.xhr.open("get", url, true);
        this.xhr.send();
    }

    post(url, parameters, callback, type = "text")
    {
        let data = this.parseparameters(parameters);
        this.type = type;
        this.callback = callback;
        this.xhr.open("post", url, true);
        this.xhr.setrequestheader("content-type", "application/x-www-form-urlencoded");
        this.xhr.send(data);
    }

    parseparameters(parameters)
    {
        // username=zhangsan&age=20
        let buildstr = "";
        for (let key in parameters) {
            let str = key + "=" + parameters[key];
            buildstr += str + "&";
        }
        return buildstr.substring(0, buildstr.length - 1);
    }
};

<!doctype html>
<html lang="zh-cn">

<head>
    <meta charset="utf-8">
    <meta http-equiv="x-ua-compatible" content="ie=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <!-- 上述3个meta标签*必须*放在最前面，任何其他内容都*必须*跟随其后！ -->
    <title>文件上传和下载</title>
    <!-- bootstrap -->
    <link href="style/css/bootstrap.min.css" rel="stylesheet">
    <link href="style/css/site.min.css" rel="stylesheet">
    <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/4.7.0/css/font-awesome.min.css">
    <style>
        .projects .thumbnail .caption {
            height: auto;
            max-width: auto;
        }
        .image{
            margin:10px auto;
            border-radius:5px;
            overflow:hidden;
            border:1px solid #ccc;
        }
        .image .caption p{
            text-align: center;
        }
    </style>
</head>

<body>
    <!--导航栏-->
    <div class="navbar navbar-inverse navbar-fixed-top">
        <div class="container">
            <div class="navbar-header">
                <button class="navbar-toggle collapsed" type="button" data-toggle="collapse" data-target=".navbar-collapse">
                  <span class="sr-only">toggle navigation</span>
                  <span class="icon-bar"></span>
                  <span class="icon-bar"></span>
                  <span class="icon-bar"></span>
                </button>
                <a class="navbar-brand hidden-sm" href="" onclick="_hmt.push(['_trackevent', 'navbar', 'click', 'navbar-首页'])">xx网</a>
            </div>
            <div class="navbar-collapse collapse" role="navigation">
                <ul class="nav navbar-nav">
                    <li class="hidden-sm hidden-md">
                        <a href="" target="_blank"></a>
                    </li>
                    <li>
                        <a href="" target="_blank"></a>
                    </li>
                </ul>
            </div>
        </div>
    </div>
    <!--导航栏结束-->
    <!--巨幕-->
    <div class="jumbotron masthead">
        <div class="container">
            <h1>文件上传下载</h1>
            <h2>实现文件的上传和下载功能</h2>
            <p class="masthead-button-links">
                <form class="form-inline" onsubmit="return false;">
                    <div class="form-group">
                        <input type="search" class="form-control keywords" id="exampleinputname2" placeholder="输入搜索内容" name="keywords" value="">
                        <button class="btn btn-default searchbtn" type="submit">搜索</button>
                        <button type="button" class="btn btn-primary btn-default" data-toggle="modal" data-target="#mymodal">  上传  </button>
                    </div>
                </form>
            </p>
        </div>
    </div>
    <!--巨幕结束-->
    <!-- 模态框 -->
    <div class="modal fade" id="mymodal" tabindex="-1" role="dialog" aria-labelledby="mymodallabel">
        <div class="modal-dialog" role="document">
            <form class="form-inline" action="upload_class.php" method="post" enctype="multipart/form-data">
                <input type="hidden" name="max_file_size" value="10240000" />
                <div class="modal-content">
                    <div class="modal-header">
                        <button type="button" class="close" data-dismiss="modal" aria-label="close"><span aria-hidden="true">&times;</span></button>
                        <h4 class="modal-title" id="mymodallabel">上传图片</h4>
                    </div>
                    <div class="modal-body">
                        <p>选择图片：</p><input type="file" id="image" name="test_pic[]">
                        <br/>
                        <p>图片描述：</p><textarea class="form-control" cols="75" name="description" id="info"></textarea>
                        <br/><br/>
                        <p>
                          是否添加水印：
                          <select name="mark">
                            <option value="1">添加</option>
                            <option value="0">不添加</option>
                          </select>
                        </p>
                        <br/>
                        <p>
                          图片宽度比例：
                            <select name="scale">
                              <option value="800*600">800*600</option>
                              <option value="600*450">600*450</option>
                              <option value="400*300">400*300</option>
                            </select>
                        </p>
                    </div>
                    <div class="modal-footer">
                        <button type="submit" class="btn btn-default" name="submit" id="submit" onclick="show(this)">上传</button>
                        <button type="reset" class="btn btn-primary">重置</button>
                    </div>
                </div>
            </form>
        </div>
    </div>
    <!--模态框结束-->

    <div class="container projects">
        <div class="projects-header page-header">
            <h2>上传图片展示</h2>
            <p>将上传的图片展示在页面中</p>
        </div>
        <div class="row pic_body">
            <!-- 使用js显示图片 -->
        </div>
        <!--分页-->
        <nav aria-label="page navigation" style="text-align:center">
            <ul class="pagination pagination-lg">
                <!-- 使用js显示页码 -->
            </ul>
        </nav>
    </div>

    <footer class="footer  container">
        <div class="row footer-bottom">
            <ul class="list-inline text-center">
                <h4><a href="class.test.com" target="_blank">class.test.com</a> | xx网</h4>
            </ul>
        </div>
    </footer>

    <!-- jquery (necessary for bootstrap's javascript plugins) -->
    <script src="style/js/jquery.min.js"></script>
    <!-- include all compiled plugins (below), or include individual files as needed -->
    <script src="style/js/bootstrap.min.js"></script>
    <script type="text/javascript">
        function show(){
          if(document.getelementbyid("image").value == ''){
            alert('请选择图片');
          }
          if(document.getelementbyid("info").value == ''){
            alert('请输入图片描述');
          }
        }
    </script>
    <!-- jquery first, then popper.js, then bootstrap js -->
    <script src="https://code.jquery.com/jquery-3.2.1.slim.min.js" integrity="sha384-kj3o2dktikvyik3uenzmm7kckrr/re9/qpg6aazgjwfdmvna/gpgff93hxpg5kkn" crossorigin="anonymous"></script>
    <script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.12.9/umd/popper.min.js" integrity="sha384-apnbgh9b+y1qktv3rn7w3mgpxhu9k/scqsap7huibx39j7fakfpskvxusvfa0b4q" crossorigin="anonymous"></script>
    <script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/js/bootstrap.min.js" integrity="sha384-jzr6spejh4u02d8jot6vlehfe/jqgirrsqqxsffwpi1mquvdayjuar5+76pvcmyl" crossorigin="anonymous"></script>
    <script src="style/js/ajax.js"></script>
    <script>
        let pageno = 1;
        let kws = '';
        let searchbtn = document.getelementsbyclassname('searchbtn')[0];
        searchbtn.onclick = function() {
            let search = document.getelementsbyclassname('keywords')[0];
            let keywords = search.value;
            requestdata(pageno, keywords);
            kws = keywords;
        };

        let requestpage = function(page) {
            requestdata(page, kws);
            pageno = page;
        };


        let requestdata = function(page_number, keywords) {
            let pagination = document.getelementsbyclassname('pagination')[0];
            let pic_body = document.getelementsbyclassname('pic_body')[0];
            pic_body.innerhtml = '<p style="text-align:center"><i class="fa fa-spinner fa-spin" style="font-size:24px"></i> 加载中...</p>';
            $.get('search.php', {"page": page_number, "keywords": keywords}, function (res) {
                let divs = '';
                if (res.code == 1) {
                    // 请求成功
                    res.rows.foreach(function (item) {
                        let div = '<div class="col-sm-6 col-md-3 col-lg-4"><div class="image"><a href="' + item.path + '" target="_blank"><img class="img-responsive" src="' + item.path + '" ></a><div class="caption"><p>' + item.info + '</p></div></div></div>';
                        divs += div;
                    });
                    pic_body.innerhtml = divs;


                    // 加载页码导航
                    // previous
                    let previousbtn = '';
                    if (res.page_number == 1) {
                        previousbtn = '<li class="page-item disabled"><a class="page-link" href="javascript:requestpage(' + (res.page_number - 1) + ');">previous</a></li>';
                    } else {
                        previousbtn = '<li class="page-item"><a class="page-link" href="javascript:requestpage(' + (res.page_number - 1) + ');">previous</a></li>';
                    }
                    // next
                    let nextbtn = '';
                    if (res.page_total == res.page_number) {
                        nextbtn = '<li class="page-item disabled"><a class="page-link" href="javascript:requestpage(' + (res.page_number + 1) + ');">next</a></li>';
                    } else {
                        nextbtn = '<li class="page-item"><a class="page-link" href="javascript:requestpage(' + (res.page_number + 1) + ');">next</a></li>'
                    }

                    let pages = previousbtn;
                    for (let page = 1; page <= res.page_total; page++) {
                        let active = '';
                        if (page == res.page_number) {
                            active = 'active';
                        }
                        pages += '<li class="page-item ' + active + '"><a class="page-link" href="javascript:requestpage(' + page + ');">' + page + '</a></li>';
                    }
                    pages += nextbtn;
                    pagination.innerhtml = pages;
                }   
            },'json');
        };
        requestdata(1, '');
    </script>
</body>
</html>

<?php

//接收传过来的数据
$description=$_post['description'];//描述
$mark=$_post['mark'];//水印
$scale=$_post['scale'];//比例 800*600
$path='';//图片存储路径


//根据比例获取宽高
$width=substr($scale,0,3);//800
$height=substr($scale,4,3);//600


//上传图片并存储
require('uploadfile.php');

$upload = new uploadfile('test_pic');
$upload->setdestinationdir('./uploads');
$upload->setallowmime(['image/jpeg', 'image/gif','image/png']);
$upload->setallowext(['gif', 'jpeg','jpg','png']);
$upload->setallowsize(2*1024*1024);
if ($upload->upload()) {
    $filename=$upload->getfilename()[0];
    $dir=$upload->getdestinationdir();
    $path=$dir.'/'.$filename;//图片存储的实际路径
    
} else {
    var_dump($upload->geterrors());
}


//根据比例调整图像
require_once './lib/image.php';
$image = new \test\lib\image($path);
//放大并保存
$image->resize($width,$height)->save($path);

$info = getimagesize($path);
//根据不同的图像type 来创建图像
switch($info[2])
{
    case 1://imagetype_gif
        $image = imagecreatefromgif($path);
        break;
    case imagetype_jpeg:
        $image = imagecreatefromjpeg($path);
        break;
    case 3:
        $image = imagecreatefrompng($path);
        break;

    default:
        echo '图像格式不支持';
        break;

}
    
//添加水印
if($mark==1){

    $logo=imagecreatefrompng('./uploads/logo.png');
    //添加水印
    imagecopy($image,$logo,0,0,0,0,imagesx($logo),imagesy($logo));
    //header('content-type:image/png');
    imagejpeg($image,$path);
}

$dst_image=imagecreatetruecolor($width,$height);
//拷贝源图像左上角起始
imagecopy( $dst_image, $image, 0, 0, 0, 0, $width, $height );
imagejpeg($dst_image,$path);

//存入数据库
$servername = "localhost";
$username = "root";
$password = "123456";
$dbname = "pic";

try {
$conn = new pdo("mysql:host=$servername;dbname=$dbname", $username, $password);
// 设置 pdo 错误模式，用于抛出异常
$conn->setattribute(pdo::attr_errmode, pdo::errmode_exception);
$sql = "insert into pic(`path`, `mark`, `scale`,`info`)
values ('$path', '$mark', '$scale','$description')";
// 使用 exec() ，没有结果返回
$conn->exec($sql);
    exit("<script>alert(\"图片上传成功!\");window.location=\"index.php\";</script>");
}
catch(pdoexception $e)
{
    echo $sql . "<br>" . $e->getmessage();
}

<?php
/**
 * created by phpstorm.
 * user: jasonlee
 * date: 2018/11/11
 * time: 22:01
 */

class uploadfile
{

    /**
     *
     */
    const upload_error = [
        upload_err_ini_size => '文件大小超出了php.ini当中的upload_max_filesize的值',
        upload_err_form_size => '文件大小超出了max_file_size的值',
        upload_err_partial => '文件只有部分被上传',
        upload_err_no_file => '没有文件被上传',
        upload_err_no_tmp_dir => '找不到临时目录',
        upload_err_cant_write => '写入磁盘失败',
        upload_err_extension => '文件上传被扩展阻止',
    ];

    /**
     * @var
     */
    protected $field_name;

    /**
     * @var string
     */
    protected $destination_dir;

    /**
     * @var array
     */
    protected $allow_mime;

    /**
     * @var array
     */
    protected $allow_ext;

    /**
     * @var
     */
    protected $file_org_name;

    /**
     * @var
     */
    protected $file_type;

    /**
     * @var
     */
    protected $file_tmp_name;

    /**
     * @var
     */
    protected $file_error;

    /**
     * @var
     */
    protected $file_size;

    /**
     * @var array
     */
    protected $errors;

    /**
     * @var
     */
    protected $extension;

    /**
     * @var
     */
    protected $file_new_name;

    /**
     * @var float|int
     */
    protected $allow_size;

    /**
     * uploadfile constructor.
     * @param $keyname
     * @param string $destinationdir
     * @param array $allowmime
     * @param array $allowext
     * @param float|int $allowsize
     */
    public function __construct($keyname, $destinationdir = './uploads', $allowmime = ['image/jpeg', 'image/gif'], $allowext = ['gif', 'jpeg'], $allowsize = 2*1024*1024)
    {
        $this->field_name = $keyname;
        $this->destination_dir = $destinationdir;
        $this->allow_mime = $allowmime;
        $this->allow_ext = $allowext;
        $this->allow_size = $allowsize;
    }

    /**
     * @param $destinationdir
     */
    public function setdestinationdir($destinationdir)
    {
        $this->destination_dir = $destinationdir;
    }

    /**
     * @param $allowmime
     */
    public function setallowmime($allowmime)
    {
        $this->allow_mime = $allowmime;
    }

    /**
     * @param $allowext
     */
    public function setallowext($allowext)
    {
        $this->allow_ext = $allowext;
    }

    /**
     * @param $allowsize
     */
    public function setallowsize($allowsize)
    {
        $this->allow_size = $allowsize;
    }

    /**
     * @return bool
     */
    public function upload()
    {
        // 判断是否为多文件上传
        $files = [];
        if (is_array($_files[$this->field_name]['name'])) {
            foreach($_files[$this->field_name]['name'] as $k => $v) {
                $files[$k]['name'] = $v;
                $files[$k]['type'] = $_files[$this->field_name]['type'][$k];
                $files[$k]['tmp_name'] = $_files[$this->field_name]['tmp_name'][$k];
                $files[$k]['error'] = $_files[$this->field_name]['error'][$k];
                $files[$k]['size'] = $_files[$this->field_name]['size'][$k];
            }
        } else {
            $files[] = $_files[$this->field_name];
        }

        foreach($files as $key => $file) {
            // 接收$_files参数
            $this->setfileinfo($key, $file);

            // 检查错误
            $this->checkerror($key);

            // 检查mime类型
            $this->checkmime($key);

            // 检查扩展名
            $this->checkext($key);

            // 检查文件大小
            $this->checksize($key);

            // 生成新的文件名称
            $this->generatenewname($key);

            if (count((array)$this->geterror($key)) > 0) {
                continue;
            }
            // 移动文件
            $this->movefile($key);
        }
        if (count((array)$this->errors) > 0) {
            return false;
        }
        return true;
    }

    /**
     * @return array
     */
    public function geterrors()
    {
        return $this->errors;
    }

    /**
     * @param $key
     * @return mixed
     */
    protected function geterror($key)
    {
        return $this->errors[$key];
    }

    /**
     *
     */
    protected function setfileinfo($key, $file)
    {
        // $_files  name type temp_name error size
        $this->file_org_name[$key] = $file['name'];
        $this->file_type[$key] = $file['type'];
        $this->file_tmp_name[$key] = $file['tmp_name'];
        $this->file_error[$key] = $file['error'];
        $this->file_size[$key] = $file['size'];
    }


    /**
     * @param $key
     * @param $error
     */
    protected function seterror($key, $error)
    {
        $this->errors[$key][] = $error;
    }


    /**
     * @param $key
     * @return bool
     */
    protected function checkerror($key)
    {
        if ($this->file_error > upload_err_ok) {
            switch($this->file_error) {
                case upload_err_ini_size:
                case upload_err_form_size:
                case upload_err_partial:
                case upload_err_no_file:
                case upload_err_no_tmp_dir:
                case upload_err_cant_write:
                case upload_err_extension:
                    $this->seterror($key, self::upload_error[$this->file_error]);
                    return false;
            }
        }
        return true;
    }


    /**
     * @param $key
     * @return bool
     */
    protected function checkmime($key)
    {
        if (!in_array($this->file_type[$key], $this->allow_mime)) {
            $this->seterror($key, '文件类型' . $this->file_type[$key] . '不被允许!');
            return false;
        }
        return true;
    }


    /**
     * @param $key
     * @return bool
     */
    protected function checkext($key)
    {
        $this->extension[$key] = pathinfo($this->file_org_name[$key], pathinfo_extension);
        if (!in_array($this->extension[$key], $this->allow_ext)) {
            $this->seterror($key, '文件扩展名' . $this->extension[$key] . '不被允许！');
            return false;
        }
        return true;
    }

    /**
     * @return bool
     */
    protected function checksize($key)
    {
        if ($this->file_size[$key] > $this->allow_size) {
            $this->seterror($key, '文件大小' . $this->file_size[$key] . '超出了限定大小' . $this->allow_size);
            return false;
        }
        return true;
    }


    /**
     * @param $key
     */
    protected function generatenewname($key)
    {
        $this->file_new_name[$key] = uniqid() . '.' . $this->extension[$key];
    }


    /**
     * @param $key
     * @return bool
     */
    protected function movefile($key)
    {
        if (!file_exists($this->destination_dir)) {
            mkdir($this->destination_dir, 0777, true);
        }
        $newname = rtrim($this->destination_dir, '/') . '/' . $this->file_new_name[$key];
        if (is_uploaded_file($this->file_tmp_name[$key]) && move_uploaded_file($this->file_tmp_name[$key], $newname)) {
            return true;
        }
        $this->seterror($key, '上传失败！');
        return false;
    }

    /**
     * @return mixed
     */
    public function getfilename()
    {
        return $this->file_new_name;
    }

    /**
     * @return string
     */
    public function getdestinationdir()
    {
        return $this->destination_dir;
    }

    /**
     * @return mixed
     */
    public function getextension()
    {
        return $this->extension;
    }

    /**
     * @return mixed
     */
    public function getfilesize()
    {
        return $this->file_size;
    }

}

<?php

// 接收请求数据
$pageno = $_get['page'] ?? 1;
$pagesize = 9;

// 接收查询参数
$keywords = $_get['keywords'] ?? '';

$data = [];
//模拟加载中的图标sleep(3);
try {
    $pdo = new pdo('mysql:host=localhost:3306;dbname=pic',
        'root',
        '123456',
        [pdo::attr_errmode => pdo::errmode_exception]
    );

    // 请求mysql 查询记录总数
    $sql = 'select count(*) as aggregate from pic';
    if (strlen($keywords) > 0) {
        $sql .= ' where info like ?';
    }
    $stmt = $pdo->prepare($sql);
    if (strlen($keywords) > 0) {
        $stmt->bindvalue(1, '%' . $keywords . '%', pdo::param_str);
    }
    $stmt->execute();
    $total = $stmt->fetch(pdo::fetch_assoc)['aggregate'];
    
    // 计算最大页码，设置页码边界
    $minpage = 1;
    $maxpage = ceil($total / $pagesize); // 3.6
    $pageno = max($pageno, $minpage);
    $pageno = min($pageno, $maxpage);
    $offset = ($pageno - 1) * $pagesize;


    $sql="select `path`,`info` from pic ";
    if (strlen($keywords) > 0) {
        $sql .= ' where info like ?';
    }
    $sql .= 'order by id desc limit ?, ?';
    $stmt = $pdo->prepare($sql);
    if (strlen($keywords) > 0) {
        $stmt->bindvalue(1, '%' . $keywords . '%', pdo::param_str);
        $stmt->bindvalue(2, (int)$offset, pdo::param_int);
        $stmt->bindvalue(3, (int)$pagesize, pdo::param_int);
    } else {
        $stmt->bindvalue(1, (int)$offset, pdo::param_int);
        $stmt->bindvalue(2, (int)$pagesize, pdo::param_int);
    }
    $stmt->execute();
    $results = $stmt->fetchall(pdo::fetch_assoc);
    $data = [
        'code' => 1,
        'msg' => 'ok',
        'rows' => $results,
        'total_records' => (int)$total,
        'page_number' => (int)$pageno,
        'page_size' => (int)$pagesize,
        'page_total' => (int)$maxpage,
    ];   

} catch (pdoexception $e) {
    $data = [
        'code' => 0,
        'msg' => $e->getmessage(),
        'rows' => [],
        'total_records' => 0,
        'page_number' => 0,
        'page_size' => (int)$pagesize,
        'page_total' => 0,
    ];
}

header('content-type: application/json');
echo json_encode($data);

/*
navicat mysql data transfer

source server         : localhost
source server version : 80012
source host           : localhost:3306
source database       : pic

target server type    : mysql
target server version : 80012
file encoding         : 65001

date: 2020-01-14 16:22:49
*/

set foreign_key_checks=0;

-- ----------------------------
-- table structure for pic
-- ----------------------------
drop table if exists `pic`;
create table `pic` (
  `id` int(10) unsigned not null auto_increment,
  `path` varchar(255) default null,
  `mark` tinyint(3) default null,
  `scale` varchar(255) default null,
  `info` varchar(255) default null,
  primary key (`id`)
) engine=myisam auto_increment=3 default charset=utf8;

-- ----------------------------
-- records of pic
-- ----------------------------
insert into `pic` values ('1', './uploads/5e1d788084cc5.jpg', '1', '800*600', '这是测试图片1');
insert into `pic` values ('2', './uploads/5e1d789766591.jpg', '1', '600*450', '这是测试图片2');