com.redhat.red.offliner.ChecksumOutputStream.java Source code

Introduction

Here is the source code for com.redhat.red.offliner.ChecksumOutputStream.java

Source

/**
 * Copyright (C) 2015 Red Hat, Inc. (jcasey@redhat.com)
 *
 * 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.
 */
package com.redhat.red.offliner;

import org.apache.commons.codec.binary.Hex;
import org.apache.commons.io.IOUtils;

import java.io.FilterOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.io.PrintStream;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

/**
 * Calculates a SHA-256 checksum while the stream it wraps is written to, for later verification.
 */
public final class ChecksumOutputStream extends FilterOutputStream {
    private MessageDigest digest;

    public ChecksumOutputStream(final OutputStream out) throws NoSuchAlgorithmException {
        super(out);
        this.digest = MessageDigest.getInstance("SHA-256");
    }

    @Override
    public void write(int b) throws IOException {
        super.write(b);
        this.digest.update((byte) b);
    }

    public String getChecksum() {
        return Hex.encodeHexString(digest.digest());
    }
}