Book Image

The Java Workshop

By : David Cuartielles, Andreas Göransson, Eric Foster-Johnson
Book Image

The Java Workshop

By: David Cuartielles, Andreas Göransson, Eric Foster-Johnson

Overview of this book

Java is a versatile, popular programming language used across a wide range of industries. Learning how to write effective Java code can take your career to the next level, and The Java Workshop will help you do just that. This book is designed to take the pain out of Java coding and teach you everything you need to know to be productive in building real-world software. The Workshop starts by showing you how to use classes, methods, and the built-in Collections API to manipulate data structures effortlessly. You’ll dive right into learning about object-oriented programming by creating classes and interfaces and making use of inheritance and polymorphism. After learning how to handle exceptions, you’ll study the modules, packages, and libraries that help you organize your code. As you progress, you’ll discover how to connect to external databases and web servers, work with regular expressions, and write unit tests to validate your code. You’ll also be introduced to functional programming and see how to implement it using lambda functions. By the end of this Workshop, you’ll be well-versed with key Java concepts and have the knowledge and confidence to tackle your own ambitious projects with Java.
Table of Contents (20 chapters)

Using HttpUrlConnection

The java.net.HttpUrlConnection class provides the main way to access HTTP resources from Java. To establish an HTTP connection, you can use code like the following:

String path = "http://example.com";
URL url = new URL(path);
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
connection.setRequestMethod("HEAD");

This code sets up a URL initialized with a link to example.com. The openConnection() method on the URL then returns HttpUrlConnection. Once you have HttpUrlConnection, you can set the HTTP method (HEAD, in this case). You can get data from the server, upload data to the server, and specify request headers.

With HttpUrlConnection, you can call setRequestProperty() to specify a request header:

connection.setRequestProperty("User-Agent", "Mozilla/5.0");

Each request generates a response, which may be successful or not. To check the response, get the response code:

int responseCode...