文件上传和下载实例源码

效果图

首先是封装好的图片类（缩放及生成水印）

GDBasic.php

<?php
/**
 * GDBasic.php
 * description GD基础类
 */

namespace testLib;


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;
    }
}

Image.php

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

namespace testLib;

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;
        }

    }
}

style样式不是重点，先不放了

然后是ajax类封装的文件 ajax.js

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);
    }
};

首页文件index.php

<!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- 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>

图片相关功能处理 upload_class.php

<?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';
$image = new 	estLibImage($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();
}

封装好的文件上传类 UploadFile.php

<?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;
    }

}

搜索功能实现 search.php

<?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);

最后数据库格式 

/*
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');