在项目开发的过程中，可能会牵扯到大量的图片，PDF,ZIP等文件。这些文件不会放在本地或者本项目下。他们会有一个专门的图片服务器。如果你够细心的话你会发现，你从百度上下载下来的图片的网址都会有http://img.qkhl.net　注意这个就是一个图片服务器。实现文件上传到远程服务器，我用的是plupload来实现的。http://www.cnblogs.com/2050/p/3913184.html 插件可以在官网上download
用 plupload上传的思路是：在本地选择文件上传，在远程服务器那边接收，并且返回图片地址，在保存到数据库中即可。在上传的过程中要注意的是路径要保证正确。
plupload功能比较强大，不仅可以实现远程上传，也可以实现本地上传。
*html代码：

<div class="cont_box cont_boxH2 uploadBook">
    <div class="cont_inner">
        <div class="add_title clearself">
            <span class="fl">位置：教辅图书列表</span>
            <script type="text/javascript" src="<?= base_url('script/plupload/plupload.full.min.js') ?>"></script>


            <script type="text/javascript" src="<?= base_url('script/plupload/jquery-ui.min.js') ?>" charset="UTF-8"></script>

            <script type="text/javascript" src="<?= base_url('script/plupload/i18n/zh_CN.js') ?>"></script>
            <script type="text/javascript" src="<?= base_url('script/plupload/jquery.ui.plupload/jquery.ui.plupload.min.js') ?>" charset="UTF-8"></script>

        </div>
        <div class="stepNumb">
            2、上传图书
        </div>
        <div class="stepTips inline-block-parent">
            <div class="step stepActive inline-block">1<div class="stepFont stepF1 stepFontActive">添加图书信息</div></div>
            <div class="line lineActive inline-block"></div>
            <div class="step stepActive inline-block">2<div class="stepFont stepFontActive">上传图书</div></div>
            <div class="line lineActive inline-block"></div>
            <div class="step inline-block">3<div class="stepFont stepF1">设置图书价格</div></div>
        </div>
        <!--上传pdf开始-->
        <form action="" method="post" enctype="multipart/form-data" id="upapk">
            <!--第一个开始-->
            <div class="upload">
                <span class="inline-block">上传PDF:</span>
                <div class="uploadInput inline-block">
                    <input type="text" id="filename" style="width: 80%;height: 100%;">
                    <div class="file fr">
                        <a  href="javascript:;" id="list_browse" >选择文件</a>
                    </div>
                </div>
                <span id="jd"></span><input type="hidden" name="filepath" id="filepath" >
            </div>
            <div class="book_box" id="file-list"></div>
            <!--第一个结束-->
            <!--第二个开始-->
            <div class="upload">
                <span class="inline-block">上传PDF:</span>
                <div class="uploadInput inline-block">
                    <input type="text" id="filename1" style="width: 80%;height: 100%;">
                    <div class="file fr">
                        <a  href="javascript:;" id="list_browse1" >选择文件</a>
                    </div>
                </div>
                <span id="jd1"></span><input type="hidden" name="filepath" id="filepath" >
            </div>
            <div class="book_box" id="file-list1"></div>
            <!--第二个结束-->
            <div class="nextStep">
                <input type="button" id="uploadfile" style="background-color: initial;" value="提交" />
            </div>
        </form>
        <!--上传结束-->


        <script src="<?= base_url('script/index.min.js') ?>"></script>
        <script>
            function DropDown(el) {
                this.dd = el;
                this.initEvents();
            }
            DropDown.prototype = {
                initEvents: function () {
                    var obj = this;
                    obj.dd.on('click', function (event) {
                        var that = this;
                        $(that).addClass("active");
                        $(".li", that).on({
                            mouseover: function () {
                                $(this).addClass("liActive");
                            },
                            mouseout: function () {
                                $(this).removeClass("liActive");
                            },
                            click: function () {
                                var optionValue = $(this).html();
                                $(".avctiveVal", that).text(optionValue);
                            }
                        });
                        $(".dropdown", that).stop().slideToggle(500);
                        $(that).siblings().find(".dropdown").slideUp("fast", function () {
                            $(that).siblings().removeClass("active");
                        });
                        event.stopPropagation(500);
                    });
                }
            };
            $(function () {
                var dd1 = new DropDown($('#dd1'));
                v`ar dd2 = new DropDown($('#dd2'));
                        var dd3 = new DropDown($('#dd3'));
                var dd4 = new DropDown($('#dd4'));
                var dd5 = new DropDown($('#dd5'));
                $(document).click(function () {
                    $('.wrapper-dropdown-2 .dropdown').slideUp(500);
                    $('.wrapper-dropdown-2').removeClass("active");
                });
            })
        </script>
        <script type="text/javascript">
//上传参数
            var callback_url = '';
            var callback_url1 = '';
            var file_path = "qw<?php echo date("Y-h-d"); ?>";
//图片列表中的上传按钮
            var uploader = new plupload.Uploader({
                runtimes: 'html5,flash,silverlight,html4',
                browse_button: ['list_browse', 'list_browse1'],
                    url: "http://img.qkhl.net/test/pdf_booky.php",
                    chunk_size: '1gb',
                    unique_names: true,
                multipart: true,
                    filters: {//uploader包含 的那些特性
                    max_file_size: '1024mb',
                    chunk_size: '1mb',
                    mime_types: [
                        {title: "Image pdf", extensions: "pdf"}
                    ]
                    },
                flash_swf_url: "<?= base_url('script/plupload/Moxie.swf') ?>",
                silverlight_xap_url: "<?= base_url('script/plupload/Moxie.xap') ?>",
                 preinit: {
                    UploadFile: function (up, file) {//当一个文件被上传时触发
                        up.setOption('multipart_params', {callback_url: [callback_url, callback_url1], file_path: file_path});
                    }
                },
                init: {
                    PostInit: function (up) {//init执行完以后要执行的触发
                        document.getElementById('uploadfile').onclick = function () {
                            if (parseInt(up.total.queued) <= 0)
                            {
                                alert("请选择上传文件");
                                uploader.stop();
                                return false;
                            }
                            uploader.start();
                            return false;
                        };
                    },
                    FilesAdded: function (up, file) {//用户选择文件触发
                        document.getElementById('filename').value = file[0]['name'];
                        document.getElementById('filename1').value = file[0]['name'];
                    },
                    UploadProgress: function (up, file) {//文件上传中触发
                        //alert(file.percent);
                        document.getElementById("jd").innerHTML = file.percent;
                        document.getElementById("jd1").innerHTML = file.percent;
                    },
                    FileUploaded: function (up, file, info) {//文件上传后触发
                        if (info['status'] != 200)
                        {
                            alert(info['result']['message']);
                            up.stop();
                            return false;
                        } else {
                            var str = info.response;
                            alert(str)
                            var json = eval('(' + str + ')');

                            if (json['status'] == 'success')
                            {
                                alert(json);
                                var img_s = json['result']['imgpath'];
                                alert(img_s)
                            }
                            else
                            {
                                //alert(info['result']['message']);
                                up.stop();
                                return false;
                            }

                        }
                    },
                    Error: function (up, args) {//上传错误时触发

                        alert('上传失败，文件错误！');
                        up.stop();
                        return false;
                    }
                }
            });
            uploader.init();
        </script>

*服务器那边的接收文件：

header('Access-Control-Allow-Origin:*'); //html5跨域接收文件
date_default_timezone_set('PRC');
@set_time_limit(5 * 60);
 * 接收参数
$file_path = isset($_POST['file_path']) ? $_POST['file_path'] : '';   //文件路径新建的文件夹
$callback_url = isset($_POST['file_path']) ? $_POST['callback_url'] : '';  //回调地址
$host_url = "task_cloud.qkhl.net";       //回调域名
$url = $host_url . $callback_url . '?1=1';
//循环POST参数
foreach ($_POST as $k => $v) {
    if ($k != 'file_path' && $k != 'callback_url') {
        $url .= '&' . $k . '=' . $v;
    }
}

if (!$file_path) {
    die('{"status" : "success", "result" : {"code": 201, "message": "data is null"}}');
}

//sleep(1); //为了显示进度条

$targetDir = $file_path;

$cleanupTargetDir = true;

$maxFileAge = 5 * 3600;

if (!file_exists($targetDir)) {
    @mkdir($targetDir);
}
if (isset($_REQUEST["name"])) {
    $fileName = $_REQUEST["name"];
} elseif (!empty($_FILES)) {
    $fileName = $_FILES["file"]["name"];
} else {
    $fileName = uniqid("file_");
}

$filePath = $targetDir . '/' . $fileName;
$ys_filePath = $targetDir . '/ys_' . $fileName;

$chunk = isset($_REQUEST["chunk"]) ? intval($_REQUEST["chunk"]) : 0;
$chunks = isset($_REQUEST["chunks"]) ? intval($_REQUEST["chunks"]) : 0;

if ($cleanupTargetDir) {
    if (!is_dir($targetDir) || !$dir = opendir($targetDir)) {
        die('{"status" : "error", "result" : {"code": 100, "message": "Failed to open temp directory."}, "id" : "id"}');
    }

    while (($file = readdir($dir)) !== false) {
        $tmpfilePath = $targetDir . '/' . $file;
        if ($tmpfilePath == "{$filePath}.part") {
            continue;
        }

        if (preg_match('/\.part$/', $file) && (filemtime($tmpfilePath) < time() - $maxFileAge)) {
            @unlink($tmpfilePath);
        }
    }
    closedir($dir);
}


if (!$out = @fopen("{$filePath}.part", $chunks ? "ab" : "wb")) {
    die('{"status" : "error", "result" : {"code": 102, "message": "Failed to open output stream."}, "id" : "id"}');
}

if (!empty($_FILES)) {
    if ($_FILES["file"]["error"] || !is_uploaded_file($_FILES["file"]["tmp_name"])) {
        die('{"status" : "error", "result" : {"code": 103, "message": "Failed to move uploaded file."}, "id" : "id"}');
    }

    if (!$in = @fopen($_FILES["file"]["tmp_name"], "rb")) {
        die('{"status" : "error", "result" : {"code": 101, "message": "Failed to open input stream."}, "id" : "id"}');
    }
} else {
    if (!$in = @fopen("php://input", "rb")) {
        die('{"status" : "error", "result" : {"code": 101, "message": "Failed to open input stream."}, "id" : "id"}');
    }
}

while ($buff = fread($in, 4096)) {
    fwrite($out, $buff);
}

@fclose($out);
@fclose($in);

if (!$chunks || $chunk == $chunks - 1) {
    rename("{$filePath}.part", $filePath);

    die('{"status" : "success", "result": {"imgpath" : "' . $filePath . '"}}');
}