In this article, you will learn how to encode and decode strings with base64 in Java. There are various utilities that provide Base64 encoding and decoding functionality in Java.
Here are the examples to encode the plain text to Base64 and decode the plain text from Base64 using Java.
The Base64 class was introduced in Java 8. The Base64 class is part of java.util class that provides static methods for the Base64 encoding and decoding scheme. This class supports three types of Base64 encoding such as Basic, URL, Filename Safe, and MIME.
In this example, you’ll learn how to encode a simple string to Base64 in Java. We used the getEncoder() method that returns a simple Base64.Encoder() and the encodeToString() method which takes a byte array as input and returns an encoded string. Let's take an example:
//Encode String to Base64 in Java
import java.util.Base64;
public class JavaPrograms {
public static void main(String[] args) {
// Normal String Encoding
String plainText = "Hello, TutorialsRack!";
ToBase64Encoded(plainText);
}
public static void ToBase64Encoded(String plainText){
Base64.Encoder simpleEncoder = Base64.getEncoder();
String encodedText = simpleEncoder.encodeToString(plainText.getBytes());
System.out.println("Base64 Encoded String: "+ encodedText);
}
}
Base64 Encoded String: SGVsbG8sIFR1dG9yaWFsc1JhY2sh
In this example, you’ll learn how to decode a simple string from Base64 in Java. We used the getDecoder() method that returns a simple Base64.Decoder() and the decode() method which takes an encoded string as input and returns a decoded string. Let's take an example:
//Decode String From Base64 in Java
import java.util.Base64;
public class JavaPrograms {
public static void main(String[] args) {
// Encoded String
String EncodedText = "SGVsbG8sIFR1dG9yaWFsc1JhY2sh";
FromBase64Decoded(EncodedText);
}
public static void FromBase64Decoded(String EncodedText) {
byte[] decodedByteArr = Base64.getDecoder().decode(EncodedText);
String decodedStr = new String(decodedByteArr);
System.out.println("Decoded String: " + decodedStr);
}
}
Decoded String: Hello, TutorialsRack!
In this example, we encode the string to Base64 without padding in Java. Padding characters helps to complete the length requirements and carries no meaning. If the encoded string's length is not a multiple of three of the string then the encoder method adds some additional padding characters(such as =) to the encoded string. Let's take an example to understand this:
//Encode String to Base64 with or Without Padding in Java
import java.util.Base64;
public class JavaPrograms {
public static void main(String[] args) {
// Normal String Encoding with Padding
String plainText = "Java World";
ToBase64Encoded(plainText);
// Normal String Encoding without Padding
ToBase64EncodedWithoutPadding(plainText);
}
// Encode String with Padding Character
public static void ToBase64Encoded(String plainText) {
Base64.Encoder simpleEncoder = Base64.getEncoder();
String encodedText = simpleEncoder.encodeToString(plainText.getBytes());
System.out.println("Base64 Encoded String With Padding: " + encodedText);
}
// Encode String without Padding Character
public static void ToBase64EncodedWithoutPadding(String plainText) {
Base64.Encoder simpleEncoder = Base64.getEncoder();
String encodedText = simpleEncoder.withoutPadding().encodeToString(plainText.getBytes());
System.out.println("Base64 Encoded String Without Padding: " + encodedText);
}
}Base64 Encoded String With Padding: SmF2YSBXb3JsZA==
Base64 Encoded String Without Padding: SmF2YSBXb3JsZA
URL encoding is very similar to basic encoding. Base64 class also handles URL encoding and decoding by using the URL and Filename safe Base64 Alphabet.
You can use the getUrlEncoder() method to get a Base64 URL encoder. Then, you can use the encodeToString() method as we did in the previous examples for encoding simple strings to Base64.
Similarly, you also have a getUrlDecoder() method that returns a URL Decoder. Again, you can use the decode() method with this decoder. Let's take an example:
//Encode and Decode URL in Java
import java.util.Base64;
public class JavaPrograms {
public static void main(String[] args) {
// Encode URL
String urlToEncode = "https://go.java/?intcmp=gojava-banner-java-com";
String encodedURL = ToBase64EncodedURL(urlToEncode);
System.out.println("Base64 Encoded URL: " + encodedURL);
// Decode URL
String decodedURL = FromBase64DecodedURL(encodedURL);
System.out.println("Base64 Decoded URL: " + decodedURL);
}
// Encode URL
public static String ToBase64EncodedURL(String plainURL) {
String encodedURL = Base64.getUrlEncoder().encodeToString(plainURL.getBytes());
return encodedURL;
}
// Decode URL
public static String FromBase64DecodedURL(String EncodedURL) {
byte[] decodedUrlBytes = Base64.getUrlDecoder().decode(EncodedURL);
String deocdedURL = new String(decodedUrlBytes);
return deocdedURL;
}
}Base64 Encoded URL: aHR0cHM6Ly9nby5qYXZhLz9pbnRjbXA9Z29qYXZhLWJhbm5lci1qYXZhLWNvbQ==
Base64 Decoded URL: https://go.java/?intcmp=gojava-banner-java-com
MIME stands for Multipurpose Internet Mail Extension, and the Base64 class uses the Base64 Alphabet for its encoding and decoding operations. In the encoded output, each line of the output is no longer than 76 characters. And also it ends with a carriage return(\r) followed by a linefeed(\n) as the line separator.
You can use the getMimeEncoder() and the encodeToString() methods for the encoding and for the decoding process, you can use getMimeDecoder() method that returns a java.util.Base64.Decoder with decode() method to decode the encoded string.
import java.util.Base64;
import java.util.UUID;
public class JavaPrograms {
public static void main(String[] args) {
// creating a MIME input for encoding
StringBuilder strBuilder = getMimeBuffer();
String encodedURL = ToBase64EncodedMIME(strBuilder);
System.out.println("Base64 Encoded: " + encodedURL);
// Decode URL
String decodedURL = FromBase64DecodedMIME(encodedURL);
System.out.println("Base64 Decoded: " + decodedURL);
}
// Method for creating a MIME input for encoding
private static StringBuilder getMimeBuffer() {
StringBuilder buffer = new StringBuilder();
for (int count = 0; count < 10; ++count) {
buffer.append(UUID.randomUUID().toString());
}
return buffer;
}
// Encoding
public static String ToBase64EncodedMIME(StringBuilder buffer) {
byte[] encodedAsBytes = buffer.toString().getBytes();
String encodedMime = Base64.getMimeEncoder().encodeToString(encodedAsBytes);
return encodedMime;
}
// Decoding
public static String FromBase64DecodedMIME(String encodedText) {
byte[] mimeDecodedBytes = Base64.getMimeDecoder().decode(encodedText);
String mimeDecodedStr = new String(mimeDecodedBytes);
return mimeDecodedStr;
}
}
The org.apache.commons.codec.binary.Base64 is not part of the default java language, it is part of a library. To use it you have to put this library on the classpath.
If you use a build and dependency management tool like maven you can add it as a dependency in the pom.xml file.
First, you need to define the commons-codec dependency in the pom.xml:
<dependencies>
<dependency>
<groupId>commons-codec</groupId>
<artifactId>commons-codec</artifactId>
<version>1.9</version>
</dependency>
</dependencies>
Once the Base64 API is created, both the encoding and decoding processes are quite simple.
import org.apache.commons.codec.binary.Base64;
public class EncodingDecodingBase64 {
public static void main(String[] args) {
String strToEncode = "Hello World";
// encoding
String encodedStr = new String(Base64.encodeBase64(strToEncode.getBytes()));
System.out.println("Encoded String: " + encodedStr);
// decoding
String decodedStr = new String(Base64.decodeBase64(encodedStr.getBytes()));
System.out.print("Decoded String: " + decodedStr);
}
}
I hope this article will help you to understand how to encode and decode strings with base64 in Java.
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