Detailed explanation of Base64 encoding and decoding in Java Library
Detailed explanation of Base64 encoding and decoding in Java Library
Base64 encoding is a encoding method that converts binary data into text format, which is often used in scenarios such as network transmission, data storage or data exchange.The Java class library provides the Base64 encoding and decoding function, which is very convenient in practical applications.This article will introduce the principles of BASE64 in the Java class library, and provide the corresponding Java code example.
The principle of the base64 encoding is to convert the binary data of 3 bytes into 4 printed characters. By processing the byte array, it is split into 6 binary numbers in several groups.Each 6 -bit binary number can be mapped to a printed character, and eventually obtains a string consisting of printed characters.The base64 encoding uses 64 characters to indicate the 64 values of 0-63. The printing characters include numbers, uppercase letters, lowercase letters, and two special characters.The coded string length is generally 4/3 times the length of the original data.
The Java class library provides two base64 encoding and decoding implementations: standard methods and URL security methods.
The standard method uses the standard Base64 character table. The encoded string contains two special characters: `+` and `/`.Code examples are as follows:
import java.util.Base64;
public class Base64Example {
public static void main(String[] args) {
String Originaltext = "Hello, World!";
// base64 encoding
String encodedText = Base64.getEncoder().encodeToString(originalText.getBytes());
System.out.println("Encoded Text: " + encodedText);
// base64 decoding
byte[] decodedBytes = Base64.getDecoder().decode(encodedText);
String decodedText = new String(decodedBytes);
System.out.println("Decoded Text: " + decodedText);
}
}
Output results:
Encoded Text: SGVsbG8sIOS4lueVjCEh
Decoded Text: Hello, the world!
The URL security method is a variant of the standard method. The encoded string replaces special characters `+` and `/` to `--` and` to avoid ambiguity in the URL.Code examples are as follows:
import java.util.Base64;
public class Base64Example {
public static void main(String[] args) {
String Originaltext = "Hello, World!";
// URL safe base64 encoding
String encodedText = Base64.getUrlEncoder().encodeToString(originalText.getBytes());
System.out.println("Encoded Text: " + encodedText);
// URL safe base64 decoding
byte[] decodedBytes = Base64.getUrlDecoder().decode(encodedText);
String decodedText = new String(decodedBytes);
System.out.println("Decoded Text: " + decodedText);
}
}
Output results:
Encoded Text: SGVsbG8sIOS4lueVjCEh
Decoded Text: Hello, the world!
The above is the principle and example of the Base64 encoding and decoding in the Java class library.Through the Base64 provided by the Java class library, we can easily encode and decode binary data to achieve the secure transmission and storage of data.
