确定InputStream的大小

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;

public class InputStreamSizeExample {
    public static void main(String[] args) {
        File file = new File("path/to/your/file.txt");
        try (FileInputStream fis = new FileInputStream(file)) {
            long size = file.length();
            System.out.println("File size: " + size + " bytes");
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

import java.io.ByteArrayInputStream;

public class InputStreamSizeExample {
    public static void main(String[] args) {
        byte[] data = "Hello, World!".getBytes();
        try (ByteArrayInputStream bais = new ByteArrayInputStream(data)) {
            int size = data.length;
            System.out.println("ByteArray size: " + size + " bytes");
        }
    }
}

import java.io.BufferedInputStream;
import java.io.FileInputStream;
import java.io.IOException;

public class InputStreamSizeExample {
    public static void main(String[] args) {
        File file = new File("path/to/your/file.txt");
        try (BufferedInputStream bis = new BufferedInputStream(new FileInputStream(file))) {
            int size = 0;
            byte[] buffer = new byte[1024];
            while (bis.read(buffer) != -1) {
                size += buffer.length;
            }
            System.out.println("BufferedInputStream size: " + size + " bytes");
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

import java.io.InputStream;
import java.net.URL;
import java.net.URLConnection;

public class InputStreamSizeExample {
    public static void main(String[] args) {
        try {
            URL url = new URL("http://example.com/data");
            URLConnection connection = url.openConnection();
            try (InputStream is = connection.getInputStream()) {
                int size = connection.getContentLength();
                if (size == -1) {
                    size = 0;
                    byte[] buffer = new byte[1024];
                    int bytesRead;
                    while ((bytesRead = is.read(buffer)) != -1) {
                        size += bytesRead;
                    }
                }
                System.out.println("InputStream size: " + size + " bytes");
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}