The working principle and application scenario of Base64 encoding in the Java class library

Base64 encoding is a encoding method that converts binary data into printed ASCII characters.The Java class library provides support for BASE64 encoding, allowing developers to easily encode and decoding data.This article will explore the working principle of Base64 encoding and introduce common application scenarios using Base64 encoding in Java. 1. The working principle of base64 encoding The base64 encoding is based on 64 printing characters, which is composed of a small and lower case letter, numbers, and two special symbols.Base64 encodes the binary data of 3 bytes into 4 printed characters, and the value range of each printed character is 0 to 63.The specific encoding process can be described as follows: 1. Divide data that need to be encoded into one group every 3 bytes. 2. Stimulate each set of data in accordance with binary methods. 3. The stitching binary data is packed in a group in a group in a group of 6 Specials (BIT) and converted into a decimal value. 4. Map the obtained decimal value through the alphabet to print as a printed character. Example of Base64 encoding: Suppose there is a data that needs to be coded as "Hello World!", And the corresponding binary data is: 01001000 01100101 01101100 01101100 01101111 00100000 01010111 01101111 01110010 01101100 01100100 00100001 Divide the above binary data into a group of bytes every 3 bytes: 01001000 01100101 01101100 01101100 01101111 00100000 01010111 01101111 01110010 01101100 01100100 00100001 The three decimal values after the conversion are: 174 229 152 108 111 32 87 111 114 108 100 33 According to the mapping rules of the Base64 alphabet, the decimal value is converted to the corresponding printed character: bf f0 gOh tdE！ The result obtained by Base64 is "BF F0 Goh TDE!". 2. The application scenario of base64 encoding 1. In the data transmission, because some protocols only support the transmission of printable characters, it is necessary to perform base64 encoding for non -printing characters (such as binary data) before transmission.For example, the attachment transmission of email will convert binary files to printed characters transmitted through base64 encoding. 2. In the encrypted scenario, the results of some encryption algorithms may include non -printed characters. In order to facilitate storage and display, Base64 is usually coded.For example, when using the RSA algorithm for encryption, the encrypted data is usually binary, and it encodes it into the Base64 string can be easily stored and transmitted. Java's support for base64 coding: In the Java 8 and above versions, the methods provided by Java.util.Base64 can be used for BASE64 encoding and decoding operations.Below is an example code that uses Base64 in the Java library: import java.util.Base64; public class Base64EncodingExample { public static void main(String[] args) { String originalData = "Hello World!"; // Use the Getencoder method of Base64 to get the Base64.encoder object Base64.Encoder encoder = Base64.getEncoder(); // Code data String encodedData = encoder.encodeToString(originalData.getBytes()); System.out.println("Encoded Data: " + encodedData); // Use the getDecoder method of Base64 to get the base64.decoder object Base64.Decoder decoder = Base64.getDecoder(); // Decoding data byte[] decodedData = decoder.decode(encodedData); String decodedString = new String(decodedData); System.out.println("Decoded Data: " + decodedString); } } The above code will output the following results: Encoded Data: SGVsbG8gV29ybGQh Decoded Data: Hello World! By using the encoding and decoding methods provided by the Java.util.Base64 class, developers can easily perform Base64 encoding and decoding operations.This makes Base64 a widely used encoding method in Java.