Java tutorial
//package com.java2s; /* * Licensed to the Apache Software Foundation (ASF) under one * or more contributor license agreements. See the NOTICE file * distributed with this work for additional information * regarding copyright ownership. The ASF licenses this file * to you 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. */ import java.io.File; import java.io.FileInputStream; import java.security.DigestInputStream; import java.security.MessageDigest; public class Main { public static String calcHash(File file, String algo) throws Exception { MessageDigest digester = MessageDigest.getInstance(algo); FileInputStream is = new FileInputStream(file); DigestInputStream dis; try { dis = new DigestInputStream(is, digester); for (byte[] buffer = new byte[1024 * 4]; dis.read(buffer) >= 0;) { // just read it } } finally { is.close(); } byte[] digest = digester.digest(); StringBuffer hash = new StringBuffer(digest.length * 2); for (int i = 0; i < digest.length; i++) { int b = digest[i] & 0xFF; if (b < 0x10) { hash.append('0'); } hash.append(Integer.toHexString(b)); } return hash.toString(); } }