Hi, this is for java and I can't figure it out. Any help would be amazing.

In Assignment 4, you wrote a simple web browser client. This time around, you will write a multithreaded webserver which will serve HTML files from the filesystem to a browser client. Write a program called Webserver.java that creates a ServerSocket object and then enters an infinite loop. The program should take the Socket returned by the ServerSockets accept() method, create a Runnable object that uses the Socket, pass this object to a Thread, start the Thread running, and go back to waiting for another client connection. The Runnable object will handle establishing the connection and serving the file.

You already know what the clients handshake string looks like:

GET HTTP/1.1

Your server should receive this string and extract the name of the file. If the request is empty (ie the name of the file is simply /), then by convention the server should load a file called index.html. You will need to look for the requested file on the filesystem and load it into memory. You will then respond to the clients request using the simplest possible HTTP response:

HTTP/1.1 200 OK

Content-type: text/html

Backslash-r and backslash-n here correspond to the carriage return and newline characters, respectively. After you send these lines, you should send the contents of the text file. If the browser asks for a file that does not exist, you should instead send the response:

HTTP/1.1 404 Not Found

If anything else goes wrong you can try to send:

HTTP/1.1 500 Internal Server Error

Important: This server is extremely insecure, and will allow a malicious user to access any textfile on your machine. You should implement a check so that the server will only send files that are located inside a particular directory designated by you. If the user tries to navigate outside of that directory (by using the parent-directory symbol ..), the server should not permit it.

Note: By convention, webservers should run on port 80. However, many operating systems protect 2- and 3-digit port numbers for security reasons, and running a Java webserver on port 80 would require running the program with administrative permissions. For that reason, it is common to choose port 8000 or 8080 for running webservers in development (like yours are). If you are running your server on port 8080, you can access it with any standard browser (Safari, Firefox, Chrome, etc.) by pointing it to http://localhost:8080.

Extra credit: Allow the server to serve images as well as HTML files. Check the filename, and if it ends with .jpg, change the HTTP content-type from text/html to image/jpeg, and load and transmit as a binary file rather than a textfile. 3 Sorting and orders of growth (35 points)