guacamole实现上传下载

分析的入手点，查看websocket连接的frame

看到首先服务端向客户端发送了filesystem请求，紧接着浏览器向服务端发送了get请求，并且后面带有根目录标识（“/”）。

1. 源码解读

查看指令

/**
 * Handlers for all instruction opcodes receivable by a Guacamole protocol
 * client.
 * @private
 */
var instructionHandlers = {
    ...其它指令
    
    "filesystem" : function handleFilesystem(parameters) {

        var objectIndex = parseInt(parameters[0]);
        var name = parameters[1];

        // Create object, if supported
        if (guac_client.onfilesystem) {
        
            //这里实例化一个object，并且传递给客户端监听的onfilesystem方法
            var object = objects[objectIndex] = new Guacamole.Object(guac_client, objectIndex);
            guac_client.onfilesystem(object, name);
        }

        // If unsupported, simply ignore the availability of the filesystem

    },
    ...其它指令
}

查看实例化的object源码

/**
 * An object used by the Guacamole client to house arbitrarily-many named
 * input and output streams.
 * 
 * @constructor
 * @param {Guacamole.Client} client
 *     The client owning this object.
 *
 * @param {Number} index
 *     The index of this object.
 */
Guacamole.Object = function guacamoleObject(client, index) {

    /**
     * Reference to this Guacamole.Object.
     *
     * @private
     * @type {Guacamole.Object}
     */
    var guacObject = this;

    /**
     * Map of stream name to corresponding queue of callbacks. The queue of
     * callbacks is guaranteed to be in order of request.
     *
     * @private
     * @type {Object.<String, Function[]>}
     */
    var bodyCallbacks = {};

    /**
     * Removes and returns the callback at the head of the callback queue for
     * the stream having the given name. If no such callbacks exist, null is
     * returned.
     *
     * @private
     * @param {String} name
     *     The name of the stream to retrieve a callback for.
     *
     * @returns {Function}
     *     The next callback associated with the stream having the given name,
     *     or null if no such callback exists.
     */
    var dequeueBodyCallback = function dequeueBodyCallback(name) {

        // If no callbacks defined, simply return null
        var callbacks = bodyCallbacks[name];
        if (!callbacks)
            return null;

        // Otherwise, pull off first callback, deleting the queue if empty
        var callback = callbacks.shift();
        if (callbacks.length === 0)
            delete bodyCallbacks[name];

        // Return found callback
        return callback;

    };

    /**
     * Adds the given callback to the tail of the callback queue for the stream
     * having the given name.
     *
     * @private
     * @param {String} name
     *     The name of the stream to associate wi