Java download an online file

The buffering and channeling capabilities allow the system to copy contents from a URL directly into the intended file without needing to save the bytes in application memory, which would be an intermediary step.

The ability to work with channels boosts performance. The downloaded contents will be transferred to a file on the local system via the corresponding file channel. After defining the file channel we will use the transferFrom method to copy the contents read from the readChannel object to the file destination using the writeChannel object.

The transferFrom and transferTo methods are much more efficient than working with streams using a buffer. The transfer methods enable us to directly copy the contents of the file system cache to the file on the system. Thus direct channeling restricts the number of context switches required and enhances the overall code performance.

Now, in the following sections, we will be looking at ways to download files from a URL using third-party libraries instead of core Java functionality components. Now you may be thinking why would we use this when Java has its own set of libraries to handle IO operations. However, Apache Commons IO overcomes the problem of code rewriting and helps avoid writing boilerplate code.

In order to start using the Apache Commons IO library, you will need to download the jar files from the official website. When you are done downloading the jar files, you need to add them to use them. If you are using an Integrated Development Environment IDE such as Eclipse , you will need to add the files to the build path of your project. There is only a single line of code required to download a file, which looks like:.

The connection and read timeouts convey the permissible time for which either the connection may stay idle or reading from the URL may stop. We will use the copy inputStream, fileOS method to download a file into the local system. Check out our hands-on, practical guide to learning Git, with best-practices, industry-accepted standards, and included cheat sheet. Stop Googling Git commands and actually learn it!

The function returns the number of bytes copied. If the value of the variable i is -1, then it indicates that the contents of the file are over 2GB. When the returned value is -1, you can use the function copyLarge inputStream, fileOS in place of the copy inputstream, fileOS function to handle this load.

Both of these functions buffer the inputstream internally. The internal buffer means we do not have to use the BufferedInputStream class to enhance our code performance and helps us avoid writing boilerplate code. This post will discuss how to download a file from a URL in Java. Using FileChannel. FileOutputStream ;. IOException ;. InputStream ;. URL ;.

Channels ;. ReadableByteChannel ;. Files ;. Paths ;. BufferedInputStream ;. FileUtils ;. File ;. Rate this post. We are sorry that this post was not useful for you! Tell us how we can improve this post? Submit Feedback. Next, we open a stream to get the bytes from the online resource and pass the inputSteam to copy.

As it takes three arguments, the first and second are the inputStream and path objects, while the third specifies the CopyOption or the way the copy operation should be performed. We use StandardCopyOption.

Download a File Using the java. FileOutputStream; import java. IOException; import java. URL; import java. Channels; import java. We use the following code to include the dependency in the project. FileUtils; import java.