FileHelper.java

/**
 * Copyright (C) 2015 Orange
 * 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.francetelecom.clara.cloud.commons.file;

import java.io.BufferedInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import java.net.URLConnection;

/**
 * FileHelper
 *   This class is an utility class which contains common file operations
 * Last update  : $LastChangedDate$
 * Last author  : $Author$
 *
 * @version : $Revision$
 */
public class FileHelper {

    /**
     * Read a content from an URL
     * @param url
     * @return byte array
     * @throws IOException
     */
    public static byte[] readBinaryFileFromUrl(URL url) throws IOException {
        URLConnection uc = url.openConnection();
        int contentLength = uc.getContentLength();
        /*
        if (contentType.startsWith("text/") || contentLength == -1) {
            throw new IOException("This is not a binary file.");
        }
        */
        InputStream raw = uc.getInputStream();
        InputStream in = new BufferedInputStream(raw);
        byte[] data = new byte[contentLength];
        int bytesRead = 0;
        int offset = 0;
        while (offset < contentLength) {
            bytesRead = in.read(data, offset, data.length - offset);
            if (bytesRead == -1)
                break;
            offset += bytesRead;
        }
        in.close();
        if (offset != contentLength) {
            throw new IOException("Only read " + offset + " bytes; Expected " + contentLength + " bytes");
        }
        return data;
    }

    /**
     * read a local file content and get the corresponding byte array
     * @param file
     * @return
     * @throws IOException
     */
    public static byte[] getBytesFromFile(File file) throws IOException {
        InputStream is = new FileInputStream(file);

        // Get the size of the file
        long length = file.length();

        // You cannot create an array using a long type.
        // It needs to be an int type.
        // Before converting to an int type, check
        // to ensure that file is not larger than Integer.MAX_VALUE.
        if (length > Integer.MAX_VALUE) {
            // File is too large
        }

        // Create the byte array to hold the data
        byte[] bytes = new byte[(int)length];

        // Read in the bytes
        int offset = 0;
        int numRead = 0;
        while (offset < bytes.length
                && (numRead=is.read(bytes, offset, bytes.length-offset)) >= 0) {
            offset += numRead;
        }

		// Close the input stream and return bytes
		is.close();

        // Ensure all the bytes have been read in
        if (offset < bytes.length) {
            throw new IOException("Could not completely read file "+file.getName());
        }

        return bytes;
    }
}