Here's the rundown on this project:

INTRODUCTION:

This is an online file browser, representing the exact files on the file system specified on the server.
(This 'specification' is done using a .properties file. Check WebContent/WEB-INF/default.properties)
Uses Java + Servlets and JSP.
Supports session-based authentication
Check the downloads section for a working WAR file (includes source)

Working the server

The server has 4 servlets:

1. auth (/OnlineFileBrowser/auth)
2. browser (/OnlineFileBrowser/browser)
3. data-transfer (/OnlineFileBrowser/data-transfer)
4. upload (/OnlineFileBrowser/upload)

auth

GET

Uses a database (MySQL in this case) to load user information based on the username & password provided.
Stores these in a session

browser

GET

GETs the information for the requested path (URI). Eg: GET /.../browser/users/arunjitsingh/uploads

POST

Creates a new directory at the requested URI. Eg: POST /.../browser/users/arunjitsingh/NEW-DIR-NAME

PUT

Rename a file at the URI with the body of the request (JSON string) containing a 'name' key with its value as the new name. Eg: PUT /.../browser/users/arunjitsingh/OLD-DIR-NAME; Request body: {"name":"NEW-DIR-NAME"}

DELETE

DELETEs a file at the URI requested. Eg: DELETE /.../browser/users/arunjitsingh/DEL-THIS-DIR

data-transfer

GET

Download the file at the URI. Directories cannot be downloaded (yet). Eg: GET /.../data-transfer/users/arunjitsingh/sample.txt

POST

Upload a file to the URI requested. Uses Apache Common's ServletFileUpload

upload

Upload a file to the URI requested. Uses Apache Common's ServletFileUpload.
Automatically redirects to upload.html#success or upload.html#failure in the root of the servlet's context.

JSON and JSONP

Google them to know what they are.

Using JSON

All requests and responses, by default, use JSON.

Using JSONP

Send the JS callback in a parameter to the request. The parameters accepted for JSONP are callback (recommended) and jsonp.