How is byte encoding and decoding implemented in Java I/O streams?

In Java I/O streams, encoding converts character data into binary data, and decoding converts binary data into character data. Encoding: Use Charset.forName() to obtain the encoding, then use Charset.encode() to encode the character data into a byte array. Decoding: Use CharsetDecoder.decode() to decode the byte array into character data. Practical case: Use BufferedWriter/BufferedReader combined with Charset to read and write text files, and specify the encoding format to ensure correct conversion of data.

Byte encoding and decoding in Java I/O streams

In Java I/O streams, byte encoding And decoding refers to the process of converting binary data into character data or vice versa. Java provides a variety of classes and methods to perform this task.

Encoding: character data to binary data

To encode character data into binary data, you can use the java.nio.charset package Charset Class. The following is an encoding example:

Charset charset = Charset.forName("UTF-8");
byte[] bytes = charset.encode("Hello World").array();

This example encodes the string "Hello World" into a UTF-8 encoded byte array.

Decoding: Binary data to character data

To decode binary data into character data, you can use the java.nio.charset package CharsetDecoder Class. The following is a decoding example:

CharsetDecoder decoder = charset.newDecoder();
String decodedString = decoder.decode(ByteBuffer.wrap(bytes)).toString();

This example decodes a UTF-8 encoded byte array into the string "Hello World".

Practical case: reading and writing text files

The following code demonstrates how to use byte encoding and decoding to read and write text files:

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.nio.charset.Charset;

public class Main {
    public static void main(String[] args) {
        // 编码：将字符串写入文本文件
        try (BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(new FileOutputStream("text.txt"), Charset.forName("UTF-8")))) {
            writer.write("Hello World");
        } catch (IOException e) {
            e.printStackTrace();
        }

        // 解码：读取文本文件中的字符串
        try (BufferedReader reader = new BufferedReader(new InputStreamReader(new FileInputStream("text.txt"), Charset.forName("UTF-8")))) {
            String line;
            while ((line = reader.readLine()) != null) {
                System.out.println(line);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

This code will write the string "Hello World" to the text.txt file in UTF-8 encoding, and then read and output the contents of the file in UTF-8 encoding.

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