com.lithium.flow.util.HashEncoder.java Source code

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Here is the source code for com.lithium.flow.util.HashEncoder.java

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/*
 * Copyright 2015 Lithium Technologies, Inc.
 *
 * 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.lithium.flow.util;

import static com.google.common.base.Preconditions.checkNotNull;

import java.io.IOException;
import java.io.InputStream;

import javax.annotation.Nonnull;

import org.apache.commons.io.IOUtils;

import com.google.common.hash.HashFunction;
import com.google.common.hash.HashingInputStream;
import com.google.common.io.BaseEncoding;
import com.google.common.io.ByteStreams;

/**
 * @author Matt Ayres
 */
public class HashEncoder {
    private final HashFunction function;
    private final BaseEncoding encoding;

    public HashEncoder(@Nonnull HashFunction function, @Nonnull BaseEncoding encoding) {
        this.function = checkNotNull(function);
        this.encoding = checkNotNull(encoding);
    }

    @Nonnull
    public String process(@Nonnull InputStream in) throws IOException {
        checkNotNull(in);
        try {
            HashingInputStream hashIn = new HashingInputStream(function, in);
            IOUtils.copy(hashIn, ByteStreams.nullOutputStream());
            return encoding.encode(hashIn.hash().asBytes());
        } finally {
            IOUtils.closeQuietly(in);
        }
    }
}