[For Java beginners] Complete guide to creating a simple web server | Learn about socket communication

"I want to experience a full-scale Java system, but I don't know where to start."
"I want to understand HTTP communication and how web servers work."
For those people, we recommendCreating a simple web serveris.

Through a web server that can be built using only Java,Socket communication, HTTP request processing, and response generationYou can learn how it works.
In this article,How to create a simple web server that anyone can implementWe will explain this in detail with example code.

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What is a simple web server?

Experience the Web with Java

Conclusion: The easiest way to experience HTTP communication in Java is to write your own web server.

Behind the scenes, when you view a web page,Server and client communicate via HTTPWe are doing it.
The easiest way to learn how this works is to actually create and run a server.

In Java,ServerSocketorSocketUsing base classes such as
A simple web server can be created with just a few hundred lines of code.is.

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Understand the basic structure of a web server

The server just "receives and returns"

In conclusion, it is a structure that reads an HTTP request and returns an HTTP response.

Basic web server flow:

1. Waiting for a connection from a client
2. Receive a request
3. Parse as a string (e.g.GET / HTTP/1.1)
4. Return a response such as HTML

The Ministry of Education, Culture, Sports, Science and Technology's "information utilization ability" also states thatUnderstanding communication is a basic skillIt is defined as (Source: https://www.mext.go.jp/a_menu/shotou/zyouhou/detail/1375607.htm).

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Preparation for using socket communication in Java

Understand the classes and mechanisms you need

Conclusion:ServerSocketandSocketThe class is central.

• ServerSocket: Listen for connections (open a port)
• Socket: Used to communicate with connected parties
• BufferedReader: Receive a request from a client
• PrintWriter:Return a response

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Implementation: Simple web server code example

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Common errors and how to fix them

This is the reason why it doesn't work or display

Bottom line: be careful with port numbers, browser caching, and request syntax.

• localhost:8080It doesn't work when I access it → Check if the port is blocked
• Your browser is using cache → Press Ctrl+F5 to force reload
• If multiple lines are not loaded, the browser may not receive the response.

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Application: What else can you do?

Let's develop the server and use it properly

Recommended additional features:

• Supports multiple HTML files (GET /about etc.)
• Threading for parallel processing
• File system integration (returning static HTML files)

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Complete code summary and configuration

• SimpleWebServer.java: Operation can be checked with a single file configuration

Combined with HTML knowledge,It can also be used as a test environment for your own web pages.

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Summary: Experience Web Communication with Java

In this article,A simple web server using JavaWe introduced how to create it.

What I learned:

• HTTP communication basics (request and response)
• ServerSocketSocket communication using
• How to structure practical Java programs

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My experience building a web server isA step towards a deeper understanding of how networks and the web workIt will be.
Please use this article as a reference and try developing your own Java server!