Java program to download a file from url

Thanks Pankaj for a very good example, explained is few simple steps. However, since I am a beginner in the field, I still cant apply the example to real exercise, I am trying to solve. Please, I need your assistance as soon as you can. Have tried with other few examples but cant just complete it. Hello sir, Actually I want to download. I went through this code with different URL but it throws the following exception could you please help me out with this problem.

The server might be blocking it, can you try after setting the User-Agent header? That way, it will look like the request is coming from a browser.

If I execute the same example I am getting below exception java. ConnectException: Connection timed out: connect at java. New HttpClient. Can you please tell me how to download file from dynamic URL www. BufferedReader; import java. File; import java. FileOutputStream; import java. FileReader; import java. IOException; import java. InputStream; import java. URL; import java.

Your email address will not be published. Pankaj I love Open Source technologies and writing about my experience about them is my passion. Follow Author. Comments Henzhi Mkali says:. May 23, at am. Jagdeep says:. There are multiple ways to download a file using Java code. Here are just a few ways of how you can accomplish the task:.

The most easily available and a basic package available for downloading a file from internet using Java code is the Java IO package. Here we will be using the BufferedInputStream and the URL classes to open and read a file on a given address to a file on our local system.

The reason we use the BufferedInputStream class instead of the InputStream is its buffering ability that gives our code a performance boost. Before we dive deeper into the coding aspect let's take an overview of the classes and the individual functions we will be using in the process. The java. URL class in Java is a built-in library that offers multiple methods to access and manipulate data on the internet.

In this case, we will be using the openStream function of the URL class. The method signature for the openStream function is:. The openStream function works on an object of the URL class. The URL class opens up a connection to the given URL and the openStream method returns an input stream which is used to read data from the connection. These classes are used for reading from a file and writing to it, respectively. The contents are read as bytes and copied to a file in the local directory using the FileOutputStream.

To lower the number of lines of code we can use the Files class available from Java 7. The Files class contains methods that read all the bytes at once and then copies it into another file. Here is how you can use it:. Java NIO is an alternative package to handle networking and input-output operations in Java.

The main advantage that the Java NIO package offers is that it's non-blocking, and has channeling and buffering capabilities. When we use the Java IO library we work with streams that read data byte by byte. However, the Java NIO package uses channels and buffers. 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:.