get SHA1 hash for File - Java Security

Java examples for Security:SHA

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Description

get SHA1 hash for File

Demo Code


//package com.java2s;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

public class Main {
    public static void main(String[] argv) throws Exception {
        File file = new File("Main.java");
        System.out.println(getSHA1(file));
    }//from  www.jav a  2s  . c o  m

    public static String getSHA1(File file) throws IOException {
        try {
            MessageDigest md = MessageDigest.getInstance("SHA1");
            FileInputStream fis = new FileInputStream(file);
            byte[] dataBytes = new byte[1024];

            int nread = 0;

            while ((nread = fis.read(dataBytes)) != -1) {
                md.update(dataBytes, 0, nread);
            }
            ;

            byte[] mdbytes = md.digest();

            //convert the byte to hex format
            StringBuffer sb = new StringBuffer("");
            for (int i = 0; i < mdbytes.length; i++) {
                sb.append(Integer.toString((mdbytes[i] & 0xff) + 0x100, 16)
                        .substring(1));
            }
            return sb.toString();
        } catch (NoSuchAlgorithmException ex) {
            throw new RuntimeException(ex);
        }
    }
}

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