How to create a data URI (base64) in Java

A note on how to generate a ** data URI ** from a file in Java

What is a data URI?

** data URI ** is base64 encoded media data etc. and is as follows

data:video/mp4;base64,AAAAIGZ0eXBpc29tAAACAGlzb21pc28y ...==


<image src="data:image/png;base64,AAAAIGZ0eXBpc29tAAAC ・ ・ ・">

<video src="data:video/mp4;base64,AAAAIGZ0eXBpc29tAAAC ・ ・ ・">

It is possible to specify src like.

1. Check the MIME type that represents the file type

Examine the MIME type of the file.

File file = new File("movie.mp4");

String contentType = Files.probeContentType(file.toPath());

2. Read all the contents of the file into the byte [] array

byte[] data = Files.readAllBytes(file.toPath());

3. Encode the byte [] array to base64

--Java 7 approach

 String base64str = DatatypeConverter.printBase64Binary(data);

--Java 8 approach

 String base64str = Base64.getEncoder().encodeToString(data);

4. Make data URI format

Format as follows

StringBuilder sb = new StringBuilder();

Full source code

package org.example;

import java.nio.file.Files;

import javax.xml.bind.DatatypeConverter;

public class ToDataURI {

	public static void main(String[] args) throws IOException {

		//Source file
		File file = new File("movie.mp4");

		//Examine the content type of a file
		String contentType = Files.probeContentType(file.toPath());

		//File contents byte[]Load into
		byte[] data = Files.readAllBytes(file.toPath());

		// byte[]To a base64 string(java7)
		String base64str = DatatypeConverter.printBase64Binary(data);

		// byte[]To a base64 string(java8)
		// String base64str = Base64.getEncoder().encodeToString(data);

		//Create a data URI
		StringBuilder sb = new StringBuilder();

		//View results


When executed, the data URI is completed

data:video/mp4;base64,AAAAIGZ0eXBpc29tAAACAGlzb21pc28yYXZjMW1wN ・ ・ ・ Omitted below

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