com.turn.ttorrent.common.Utils.java Source code

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Here is the source code for com.turn.ttorrent.common.Utils.java

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/**
 * 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
 * <p/>
 * http://www.apache.org/licenses/LICENSE-2.0
 * <p/>
 * 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.turn.ttorrent.common;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.URI;

import org.apache.commons.io.IOUtils;
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;

/**
 * Utility class for keeping common static methods
 * 
 * @author pisek
 * @since 24.11.2015
 */
public final class Utils {

    private final static char[] HEX_SYMBOLS = "0123456789ABCDEF".toCharArray();

    /**
     * Static class
     */
    private Utils() {
    }

    /**
     * Resolves a file from URI and returns its byte array.
     * 
     * @param uri
     * @return
     * @throws ClientProtocolException
     * @throws IOException
     */
    public static byte[] resolveUrlFileToByteArray(URI uri) throws ClientProtocolException, IOException {
        CloseableHttpClient httpclient = HttpClients.createDefault();

        try {

            HttpGet get = new HttpGet(uri);
            HttpResponse response = httpclient.execute(get);
            HttpEntity entity = response.getEntity();

            if (entity != null) {
                InputStream inputStream = entity.getContent();
                ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
                IOUtils.copy(inputStream, outputStream);
                return outputStream.toByteArray();
            }

            throw new IOException("Could not resolve file... [" + uri + "]");

        } finally {
            httpclient.close();
        }

    }

    /**
     * Convert a byte string to a string containing the hexadecimal
     * representation of the original data.
     *
     * @param bytes The byte array to convert.
     * @see <a href="http://stackoverflow.com/questions/332079">http://stackoverflow.com/questions/332079</a>
     */
    public static String bytesToHex(byte[] bytes) {
        char[] hexChars = new char[bytes.length * 2];
        for (int j = 0; j < bytes.length; j++) {
            int v = bytes[j] & 0xFF;
            hexChars[j * 2] = HEX_SYMBOLS[v >>> 4];
            hexChars[j * 2 + 1] = HEX_SYMBOLS[v & 0x0F];
        }
        return new String(hexChars);
    }
}