Simple question, I want to know is Java free (especially for web development). Later on if I've build a large website, w开发者_如何学Cill the servers, databases cost me much like in .net for example?

Cheers.

Java is free. Check licences of frameworks you're using, but you shouldn't worry about that since most of them are free.

Servers (physical) will, of course, cost you.

There are free application servers like Glassfish and JBoss.

There are free databases like mySQL and PostgreSQL.

So, you can get away with everything being free except hardware and, possibly, hosting of your web app.

Yes and no - depending on how big your site gets, you may be required to invest more money into better servers/databases.

It's not really something that can just be answered, without looking into the future.

Update, as of 2021

Be sure to read the document prepared by pillars of the Java community, Java is Still Free. This document provides a short overview as well as a longer section with all the gory details.

Understand that Java is a set of specifications, not a product.

• Java Language and Virtual Machine Specifications
• JEPs and JSRs

Many vendors provide binaries or installers for an implementation of Java. Nowadays, all of those implementations are based largely or entirely on the OpenJDK project. Participants including Oracle, IBM, SAP, Apple, Azul Systems, and more have banded together to pool their best technologies for implementing Java as open-source free-of-cost.

The OpenJDK project provides only source-code. Various vendors build that source code to provide binaries or installers for you and me to conveniently put Java on our computers. Some of their distributions of Java are available free-of-cost, and some are commercial with paid support. Some are general-purpose JVMs, and some are special-purpose. Some are a basic JDK and some have bundled extras.

Here is a diagram I made to help you in choosing a vendor for a Java implementation.

And some considerations to think about when choosing a vendor.