sha256-蒲公英云

sha256

import java.io.File;
import java.io.FileInputStream;
import java.math.BigInteger;
import java.security.MessageDigest;
public class SHA256File {
    String official_checksum = "";
    void OnEncFile() {
        System.out.println("Getting file...");
        File file = new File("/datas/upload/zip/bankcode_NJCBCNBN123444_20170328095225.zip");
        if (file.exists()) {
            System.out.println("File got.");
        } else {
            System.err.println("File not got.");
        }
        System.out.print("Calcuclating SHA-256 checksum......");
        String FileSHA256 = getFileSHA256(file);
        System.out.println();
        System.out.println("File's SHA-256 checksum is: ");
        System.out.println(FileSHA256);
        System.out.println(official_checksum + " --- the official checksum");
        if (official_checksum.equals(FileSHA256)) {
            System.out.println("SHA-256 checksums are the same.");
        } else {
            System.err.println("SHA-256 checksums differ!!!!");
        }
    }
    public  static String getFileSHA256(File file) {
//        if (!file.isFile()) {
//
//            System.err.println("not file");
//
//            return null;
//
//        }
        MessageDigest digest = null;
        FileInputStream in = null;
        byte buffer[] = new byte[1024];
        int len;
        try {
            digest = MessageDigest.getInstance("SHA-256");
            in = new FileInputStream(file);
            while ((len = in.read(buffer, 0, 1024)) != -1) {
                digest.update(buffer, 0, len);
            }
            in.close();
        } catch (Exception e) {
            e.printStackTrace();
            return null;
        }
        BigInteger bigInt = new BigInteger(1, digest.digest());
        return bigInt.toString(16);
    }
    public static void main(String[] args) {
        new SHA256File().OnEncFile();
    }
}