MultipartObjects.java

/*
 * Copyright 2014-2016 CyberVision, 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 org.kaaproject.kaa.server.transports.http.transport;

import java.io.DataOutputStream;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.util.HashMap;
import java.util.Map;
import java.util.Random;

/**
 * Represent Multipart mixed objects of http request
 *
 * @author Andrey Panasenko <apanasenko@cybervisiontech.com>
 */
public class MultipartObjects {

  /**
   * boundary size
   */
  public static final int BOUNDARY_LENGTH = 35;
  /**
   * ContentType constant string
   */
  public static final String CONTENT_TYPE_CONST = "multipart/form-data; boundary=";
  /**
   * ContentDisposition constant string
   */
  public static final String CONTENT_DISPOSITION = "Content-Disposition: form-data; ";
  /**
   * Content name filed
   */
  public static final String CONTENT_NAME = "name=";
  /**
   * CRLF
   */
  public static final String crlf = "\r\n";
  /**
   * The pool of ASCII chars to be used for generating a multipart boundary.
   */
  private final static char[] MULTIPART_CHARS =
      "-_1234567890abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
          .toCharArray();
  /**
   * Random number generator
   */
  private static Random rnd = new Random();
  /**
   * Generated boundary
   */
  private String boundary;
  /**
   * Multipart objects
   */
  private Map<String, ByteBuffer> objects;

  /**
   * Constructor.
   */
  public MultipartObjects() {
    boundary = getRandomString(BOUNDARY_LENGTH);
    objects = new HashMap<String, ByteBuffer>();
  }

  /**
   * Generate String with random ascii symbols from 48 till 122 with length size.
   *
   * @param size of String
   * @return String with random ascii symbols
   */
  public static String getRandomString(int size) {
    StringBuffer sb = new StringBuffer();
    for (int i = 0; i < size; i++) {
      int j = rnd.nextInt(MULTIPART_CHARS.length);
      sb.append(MULTIPART_CHARS[j]);
    }
    return sb.toString();
  }

  /**
   * Add multipart/mixed object
   *
   * @param name  - String name of object
   * @param bytes - byte[] array of object
   */
  public void addObject(String name, byte[] bytes) {
    objects.put(name, ByteBuffer.wrap(bytes));
  }

  /**
   * Generate Multipart/mixed POST request objects to DataOutputStream
   *
   * @param out - DataOutputStream of HTTP request
   * @throws IOException - if write failed
   */
  public void dumbObjects(DataOutputStream out) throws IOException {
    for (String name : objects.keySet()) {
      out.writeBytes("--" + boundary + crlf);
      out.writeBytes(CONTENT_DISPOSITION + CONTENT_NAME + "\"" + name + "\"" + crlf);
      out.writeBytes("Content-Type: application/octet-stream" + crlf);
      out.writeBytes(crlf);
      out.write(objects.get(name).array());
      out.writeBytes(crlf);
    }
    out.writeBytes("--" + boundary + "--" + crlf);
  }

  /**
   * Multipart mixed boundary getter.
   *
   * @return the boundary
   */
  public String getBoundary() {
    return boundary;
  }

  /**
   * Multipart mixed Content-Length with boundary getter.
   *
   * @return the boundary
   */
  public String getContentType() {
    return CONTENT_TYPE_CONST + boundary;
  }
}