在 Java 中解码 Base64 字符串

Question

I'm trying to decode a simple Base64 string, but am unable to do so. I'm currently using the org.apache.commons.codec.binary.Base64 package.

The test string I'm using is: abcdefg , encoded using PHP YWJjZGVmZw== .

This is the code I'm currently using:

Base64 decoder = new Base64();
byte[] decodedBytes = decoder.decode("YWJjZGVmZw==");
System.out.println(new String(decodedBytes) + "\n") ;   

The above code does not throw an error, but instead doesn't output the decoded string as expected.

Answer 1

Modify the package you're using:

import org.apache.commons.codec.binary.Base64;

And then use it like this:

byte[] decoded = Base64.decodeBase64("YWJjZGVmZw==");
System.out.println(new String(decoded, "UTF-8") + "\n");

Answer 2

The following should work with the latest version of Apache common codec

byte[] decodedBytes = Base64.getDecoder().decode("YWJjZGVmZw==");
System.out.println(new String(decodedBytes));

and for encoding

byte[] encodedBytes = Base64.getEncoder().encode(decodedBytes);
System.out.println(new String(encodedBytes));

Answer 3

If you don't want to use apache, you can use Java8:

byte[] decodedBytes = Base64.getDecoder().decode("YWJjZGVmZw=="); 
System.out.println(new String(decodedBytes) + "\n");

Answer 4

Commonly base64 it is used for images. if you like to decode an image (jpg in this example with org.apache.commons.codec.binary.Base64 package):

byte[] decoded = Base64.decodeBase64(imageJpgInBase64);
FileOutputStream fos = null;
fos = new FileOutputStream("C:\\output\\image.jpg");
fos.write(decoded);
fos.close();