The underlying principle and implementation method of Base64 decoding in the Java class library

In the Java class library, the Base64 decoding is a process of converting the data of Base64 back to the original data.Base64 encoding is a common method for network transmission, storage, and processing text data. It converts binary data into printed ASCII characters by represented each byte in the form of 6 digits. The underlying principle of Base64 decoding operation is very simple.Basically, it follows the following steps: 1. First, convert Base64 -encoded string to byte array.This can be implemented by using the Base64 method in the Java class library.This method uses the Base64 string as input and returns the corresponding byte array. 2. Then re -combine each byte in the byte array to the original data.The base64 encoding converts every 3 bytes to 4 characters, so during the decoding process, you need to re -combine the original byte data.This can be achieved through a series of bit operations. 3. Finally, for the number of bytes that are not 3 times, additional processing needs to be performed.There may be filling characters (usually equal number '=') in the base64 encoding, which is used to make up the length of the input data to multiples of 3.Therefore, when the number of bytes of decoding is not a multiples of 3, these filling characters need to be removed. Below is a simple Java code example, showing how to use the Base64 in the Java class library for decoding: import java.util.Base64; public class Base64DecodeExample { public static void main(String[] args) { String base64string = "sgvsbg8gd29ybgq ="; // base64 coding string // Decoding the base64 string byte[] decodedBytes = Base64.getDecoder().decode(base64String); // Convert byte array to string String decodedString = new String(decodedBytes); System.out.println (decodedstring); // Output: Hello World } } In the above example, we use the Base64 string in the Base64 in the Base64 in the Java class library to decoding the Base64 string.Then, by converting the decoding byte array into a string, we can get the original data "Hello World".