SpringBoot前端网页上传文件案例

#[jQuery Form Plugin](http://jquery.malsup.com/form/) ##Overview The jQuery Form Plugin allows you to easily and unobtrusively upgrade HTML forms to use AJAX. The main methods, ajaxForm and ajaxSubmit, gather information from the form element to determine how to manage the submit process. Both of these methods support numerous options which allows you to have full control over how the data is submitted. No special markup is needed, just a normal form. Submitting a form with AJAX doesn't get any easier than this! --- ##API ###jqXHR The jqXHR object is stored in element <em>data</em>-cache with the <code>jqxhr</code> key after each <code>ajaxSubmit</code> call. It can be accessed like this: ````javascript var form = $('#myForm').ajaxSubmit({ /* options */ }); var xhr = form.data('jqxhr'); xhr.done(function() { ... }); ```` ###ajaxForm( options ) Prepares a form to be submitted via AJAX by adding all of the necessary event listeners. It does **not** submit the form. Use `ajaxForm` in your document's `ready` function to prepare existing forms for AJAX submission, or with the `delegation` option to handle forms not yet added to the DOM. Use ajaxForm when you want the plugin to manage all the event binding for you. ````javascript // prepare all forms for ajax submission $('form').ajaxForm({ target: '#myResultsDiv' }); ```` ###ajaxSubmit( options ) Immediately submits the form via AJAX. In the most common use case this is invoked in response to the user clicking a submit button on the form. Use ajaxSubmit if you want to bind your own submit handler to the form. ````javascript // bind submit handler to form $('form').on('submit', function(e) { e.preventDefault(); // prevent native submit $(this).ajaxSubmit({ target: 'myResultsDiv' }) }); ```` --- ##Options Note: all standard [$.ajax](http://api.jquery.com/jQuery.ajax) options can be used. ###beforeSerialize Callback function invoked prior to form serialization. Provides an opportunity to manipulate the form before its values are retrieved. Returning `false` from the callback will prevent the form from being submitted. The callback is invoked with two arguments: the jQuery wrapped form object and the options object. ````javascript beforeSerialize: function($form, options) { // return false to cancel submit } ```` ###beforeSubmit Callback function invoked prior to form submission. This provides an opportunity to manipulate the form before it's values are retrieved. Returning `false` from the callback will prevent the form from being submitted. The callback is invoked with three arguments: the form data in array format, the jQuery wrapped form object, and the options Oobject. ````javascript beforeSubmit: function(arr, $form, options) { // form data array is an array of objects with name and value properties // [ { name: 'username', value: 'jresig' }, { name: 'password', value: 'secret' } ] // return false to cancel submit } ```` ###clearForm Boolean flag indicating whether the form should be cleared if the submit is successful ###data An object containing extra data that should be submitted along with the form. ````javascript data: { key1: 'value1', key2: 'value2' } ```` ###dataType Expected data type of the response. One of: null, 'xml', 'script', or 'json'. The dataType option provides a means for specifying how the server response should be handled. This maps directly to jQuery's dataType method. The following values are supported: * 'xml': server response is treated as XML and the 'success' callback method, if specified, will be passed the responseXML value * 'json': server response will be evaluted and passed to the 'success' callback, if specified * 'script': server response is evaluated in the global context ###delegation true to enable support for event delegation *requires jQuery v1.7+* ````javascript // prepare all existing and future forms for ajax submission $('form').ajaxForm({ delegation: true }); ```` ###error Callback function to be invoked upon error. ###forceSync Only applicable when explicity using the iframe option or when uploading files on browses that don't support XHR2. Set to `true` to remove the short delay before posting form when uploading files. The delay is used to allow the browser to render DOM updates prior to performing a native form submit. This improves usability when displaying notifications to the user, such as "Please Wait..." ###iframe Boolean flag indicating whether the form should *always* target the server response to an iframe instead of leveraging XHR when possible. ###iframeSrc String value that should be used for the iframe's src attribute when/if an iframe is used. ###iframeTarget Identifies the iframe element to be used as the response target for file uploads. By default, the plugin will create a temporary iframe element to capture the response when uploading files. This options allows you to use an existing iframe if you wish. When using this option the plugin will make no attempt at handling the response from the server. ###replaceTarget Optionally used along with the the target option. Set to true if the target should be replaced or false if only the target contents should be replaced. ###resetForm Boolean flag indicating whether the form should be reset if the submit is successful ###semantic Boolean flag indicating whether data must be submitted in strict semantic order (slower). Note that the normal form serialization is done in semantic order with the exception of input elements of `type="image"`. You should only set the semantic option to true if your server has strict semantic requirements and your form contains an input element of `type="image"`. ###success Callback function to be invoked after the form has been submitted. If a `success` callback function is provided it is invoked after the response has been returned from the server. It is passed the following arguments: 1. responseText or responseXML value (depending on the value of the dataType option). 2. statusText 3. xhr (or the jQuery-wrapped form element if using jQuery < 1.4) 4. jQuery-wrapped form element (or undefined if using jQuery < 1.4) ###target Identifies the element(s) in the page to be updated with the server response. This value may be specified as a jQuery selection string, a jQuery object, or a DOM element. ###type The method in which the form data should be submitted, 'GET' or 'POST'. ###uploadProgress Callback function to be invoked with upload progress information (if supported by the browser). The callback is passed the following arguments: 1. event; the browser event 2. position (integer) 3. total (integer) 4. percentComplete (integer) ###url URL to which the form data will be submitted. --- ##Utility Methods ###formSerialize Serializes the form into a query string. This method will return a string in the format: `name1=value1&name2=value2` ````javascript var queryString = $('#myFormId').formSerialize(); ```` ###fieldSerialize Serializes field elements into a query string. This is handy when you need to serialize only part of a form. This method will return a string in the format: `name1=value1&name2=value2` ````javascript var queryString = $('#myFormId .specialFields').fieldSerialize(); ```` ###fieldValue Returns the value(s) of the element(s) in the matched set in an array. This method always returns an array. If no valid value can be determined the array will be empty, otherwise it will contain one or more values. ###resetForm Resets the form to its original state by invoking the form element's native DOM method. ###clearForm Clears the form elements. This method emptys all of the text inputs, password inputs and textarea elements, clears the selection in any select elements, and unchecks all radio and checkbox inputs. It does *not* clear hidden field values. ###clearFields Clears selected field elements. This is handy when you need to clear only