百度个人云盘空间大，完全免费，而且提供了pcs api供调用操作文件，在平时的项目里往里面保存一些文件是很实用的。

环境准备：

开通读写网盘的权限及获取access_token:http://blog.csdn.net/langyuezhang/article/details/47206621

百度官方pcs api文档：http://developer.baidu.com/wiki/index.php?title=docs/pcs/overview，上面有各种语言的SDK，我用的laravel5，直接导里面的php SDK还用不了，稍做了修改才能用的。

看完上面两篇文章，基本就可以使用了，下面贴出写直接把用户选择的图片预览然后upload到网盘，上传的api：
https://pcs.baidu.com/rest/2.0/pcs/file?method=upload&path=%2fapps%2wp2pcs%2f1.JPG&access_token=***红色部分是固定的，因为只允许上传到这个目录下，实际对应到网盘的目录是我的网盘/我的应用数据/wp2pcs、，无需先创建目录再上传文件，只需要指定路径，它会自动创建，如你想把图片上传到/apps/wp2pcs/img下，path就写/apps/wp2pcs/img/1.jpg就可以了。下面是把用户在网页上选择的图片，预览后直接上传到网盘的代码，参照了网上的例子：预览：

//图片上传预览 IE是用了滤镜。function previewImage(file, product){getPhotopty();console.log("previewImage");uploadAndSubmit(product);var div = document.getElementById('preview' + product);var fileName = file.value;//upload();if (file.files){var i = 0;var funAppendImage = function () {var _file = file.files[i];if (_file) {var reader = new FileReader()reader.onload = function (evt) {fileName = _file.name;div.innerHTML += '<div class="col-xs-6 col-md-3"><a style="float:right;cursor:pointer;" onclick="del(this)">X</a><div class="thumbnail"><img id=imghead' + product + fileName + '></div></div>';var img = document.getElementById('imghead' + product + fileName);img.src = evt.target.result;i++;funAppendImage();}reader.readAsDataURL(_file);}};funAppendImage();}$('#coverBg').show();$('#coverDiv').show();//$("#uploadFrm" + product).submit();}

上传：

var access_token = "***********";var baseUrl = "https://c.pcs.baidu.com/rest/2.0/pcs/";function uploadAndSubmit(product) {console.log("start uploadAndSubmit");if (typeof FileReader == 'undefined') {alert("你的浏览器不支持FileReader接口！");}var taskName = $("#txtTask").val() + "-" + $("#txtTask2").val();var form = document.forms["uploadFrm" + product];console.log("form:" + form);var fileCtrl = "filectrl" + product;console.log("filectrl:" + fileCtrl);//if (form[fileCtrl].files.length > 0)console.log($("#filectrl" + product)[0]);if ($("#filectrl" + product)[0].files.length > 0){for (var i = 0; i < $("#filectrl" + product)[0].files.length; i++){var file = form[fileCtrl].files[i];console.log(file.name);var filePath = "%2fapps%2fwp2pcs%2f" + taskName + "%2f" + file.name;console.log("add exif info to db");getExifIinfo(taskName, file, product, filePath);//document.getElementById("bytesRead").textContent = file.size;console.log("start XMLHttpRequest");var xhr = new XMLHttpRequest();console.log(access_token);var url = baseUrl + "file?method=upload&path=%2fapps%2fwp2pcs%2f" + taskName + "%2f" + file.name + "&access_token=" + access_token + "&ondup=overwrite&count=" + i;console.log(url);xhr.open("POST", url, true);var formData = new FormData();formData.append("file", file);console.log("onreadystatechange");xhr.onreadystatechange = function () {console.log("onreadystatechange start");//console.log(xhr.status);if (xhr.readyState == 4) {if (xhr.status == 200) {console.log("upload complete");console.log("response: " + xhr.responseText);var result = $.parseJSON(xhr.responseText);if (result.hasOwnProperty("path")){$("#reusltMsg").append('<div class="alert alert-success" role="alert"> 上传成功.</div>');} else{$("#reusltMsg").append('<div class="alert alert-danger" role="alert"> 上传失败.</div>');}} else{$("#reusltMsg").append('<div class="alert alert-danger" role="alert"> 上传失败(200).</div>');}}$('#coverBg').hide();$('#coverDiv').hide();}xhr.send(formData);}} else{alert("Please choose a file.");$('#coverBg').hide();$('#coverDiv').hide();}}