Comment le flux d'E/S Java effectue-t-il les opérations sur les chaînes ?

// 从 FileInputStream 中读取字符串
try (InputStreamReader reader = new InputStreamReader(new FileInputStream("input.txt"))) {
    StringBuilder sb = new StringBuilder();
    int c;
    while ((c = reader.read()) != -1) {
        sb.append((char) c);
    }
    String text = sb.toString();
} catch (IOException e) {
    e.printStackTrace();
}

// 向 FileWriter 中写入字符串
try (FileWriter writer = new FileWriter("output.txt")) {
    String text = "Hello, world!";
    writer.write(text);
    writer.flush();
} catch (IOException e) {
    e.printStackTrace();
}

import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;

class FileCopy {
    public static void main(String[] args) {
        try {
            // 从 input.txt 中读取
            File inputFile = new File("input.txt");
            FileReader reader = new FileReader(inputFile);
            BufferedReader bufferedReader = new BufferedReader(reader);

            // 向 output.txt 中写入
            File outputFile = new File("output.txt");
            FileWriter writer = new FileWriter(outputFile);

            String line;
            while ((line = bufferedReader.readLine()) != null) {
                writer.write(line + "\n");
            }

            reader.close();
            writer.close();
            System.out.println("文件已复制完成。");
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}