GenerateFileChecksum.java

/*
 * Created on 13-3-29
 * 
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
 * in compliance with the License. You may obtain a copy of the License at
 * 
 * http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software distributed under the License
 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
 * or implied. See the License for the specific language governing permissions and limitations under
 * the License.
 * 
 * Copyright @2013 the original author or authors.
 */
package ch18io.file;

/**
 * Description of this file.
 *
 * @author XiongNeng
 * @version 1.0
 * @since 13-3-29
 */

import java.io.FileInputStream;
import java.security.MessageDigest;

public class GenerateFileChecksum {

    public static void main(String args[]) throws Exception {
        String datafile = "c:\\INSTLOG.TXT";
        MessageDigest md = MessageDigest.getInstance("SHA1");
        FileInputStream fis = new FileInputStream(datafile);
        byte[] dataBytes = new byte[1024];
        int nread;
        while ((nread = fis.read(dataBytes)) != -1) {
            md.update(dataBytes, 0, nread);
        }
        byte[] mdbytes = md.digest();
        //convert the byte to hex format
        StringBuilder sb = new StringBuilder("");
        for (byte mdbyte : mdbytes) {
            sb.append(Integer.toString((mdbyte & 0xff) + 0x100, 16).substring(1));
        }
        System.out.println("Digest(in hex format):: " + sb.toString());

    }
}