How to convert an InputStream to a File in Java

In this quick article, you'll learn how to convert an instance of InputStream to a file using Java. In Java, there are several ways to do this conversion as explained below.

Using Files.copy() Method

In Java 7 or higher, you can use the Files.copy() method from Java's NIO API to copy an InputStream object to a file as shown below:

try (InputStream stream = Files.newInputStream(Paths.get("input.txt"))) {

    // convert stream to file
    Files.copy(stream, Paths.get("output.txt"));

} catch (IOException ex) {
    ex.printStackTrace();
}

The above code will throw an error if the file already exists. To replace the existing file, you can use the below example code:

try (InputStream stream = Files.newInputStream(Paths.get("input.txt"))) {

    // convert stream to file
    Files.copy(stream, Paths.get("output.txt"), StandardCopyOption.REPLACE_EXISTING);

} catch (IOException ex) {
    ex.printStackTrace();
}

Using OutputStream Class

In Java 6 or below, you can use the OutputStream class to manually copy data from InputStream to a file as shown below:

try (InputStream inputStream = new FileInputStream(new File("input.txt"));
     OutputStream outputStream = new FileOutputStream(new File("output.txt"))) {
        int length;
        byte[] bytes = new byte[1024];
        // copy data from input stream to output stream
        while ((length = inputStream.read(bytes)) != -1) {
            outputStream.write(bytes, 0, length);
        }

} catch (IOException ex) {
    ex.printStackTrace();
}

Using Apache Commons IO

The Apache Commons IO library provides IOUtils.copyInputStreamToFile() method to easily copy an instance of InputStream to a file as shown below:

try (InputStream stream = Files.newInputStream(Paths.get("input.txt"))) {

    // convert input stream to file
    FileUtils.copyInputStreamToFile(stream, new File("output.txt"));

} catch (IOException ex) {
    ex.printStackTrace();
}

Don't forget to include Apache Commons IO dependency to your Maven's project pom.xml file:

<dependency>
    <groupId>commons-io</groupId>
    <artifactId>commons-io</artifactId>
    <version>2.6</version>
</dependency>

For a Gradle project, add the following dependency to your build.gralde file:

implementation 'commons-io:commons-io:2.6'

Further Reading

You may be interested in other Java I/O articles:

✌️ Like this article? Follow me on Twitter and LinkedIn. You can also subscribe to RSS Feed.

You might also like...

Digital Ocean

The simplest cloud platform for developers & teams. Start with a $200 free credit.

Buy me a coffee ☕

If you enjoy reading my articles and want to help me out paying bills, please consider buying me a coffee ($5) or two ($10). I will be highly grateful to you ✌️

Enter the number of coffees below:

✨ Learn to build modern web applications using JavaScript and Spring Boot

I started this blog as a place to share everything I have learned in the last decade. I write about modern JavaScript, Node.js, Spring Boot, core Java, RESTful APIs, and all things web development.

The newsletter is sent every week and includes early access to clear, concise, and easy-to-follow tutorials, and other stuff I think you'd enjoy! No spam ever, unsubscribe at any time.