Java下载文件如何保证数据完整性

?Java??????????????????:

1. ??HTTP?HTTPS??:???????HTTP?HTTPS??????,???????????????????????

2. ????????:???????,????????(??MD5?SHA-1),????????????????????????????,???????????????

???????Java???????????????:

import java.io.*;
import java.net.URL;
import java.nio.file.Files;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

public class DownloadFileWithIntegrityCheck {

    public static void main(String[] args) throws IOException, NoSuchAlgorithmException {
        String fileUrl = "https://example.com/path/to/your/file.txt";
        String outputFilePath = "downloaded_file.txt";
        String expectedChecksum = "expected_checksum_value"; // ????????????????

        downloadFileWithIntegrityCheck(fileUrl, outputFilePath, expectedChecksum);
    }

    public static void downloadFileWithIntegrityCheck(String fileUrl, String outputFilePath, String expectedChecksum) throws IOException, NoSuchAlgorithmException {
        URL url = new URL(fileUrl);
        try (InputStream inputStream = url.openStream();
             BufferedInputStream bufferedInputStream = new BufferedInputStream(inputStream);
             FileOutputStream fileOutputStream = new FileOutputStream(outputFilePath);
             BufferedOutputStream bufferedOutputStream = new BufferedOutputStream(fileOutputStream)) {

            byte[] buffer = new byte[1024];
            int bytesRead;

            while ((bytesRead = bufferedInputStream.read(buffer)) != -1) {
                bufferedOutputStream.write(buffer, 0, bytesRead);
            }
        }

        String actualChecksum = calculateChecksum(outputFilePath, "MD5");
        if (actualChecksum.equals(expectedChecksum)) {
            System.out.println("???????????");
        } else {
            System.out.println("????????????");
            Files.deleteIfExists(Paths.get(outputFilePath));
        }
    }

    public static String calculateChecksum(String filePath, String algorithm) throws IOException, NoSuchAlgorithmException {
        MessageDigest messageDigest = MessageDigest.getInstance(algorithm);
        try (InputStream inputStream = Files.newInputStream(Paths.get(filePath));
             BufferedInputStream bufferedInputStream = new BufferedInputStream(inputStream)) {

            byte[] buffer = new byte[1024];
            int bytesRead;

            while ((bytesRead = bufferedInputStream.read(buffer)) != -1) {
                messageDigest.update(buffer, 0, bytesRead);
            }
        }

        byte[] checksumBytes = messageDigest.digest();
        StringBuilder sb = new StringBuilder();
        for (byte b : checksumBytes) {
            sb.append(String.format("x", b));
        }
        return sb.toString();
    }
}

??????,????????URL????,???????MD5????????????????????????????????,?????????????????,???????????????