Here you can find the source of supportedSendTypes()
public static String[] supportedSendTypes()
//package com.java2s; /* Support for the websocket accessor. // w w w . j ava2 s.co m @Copyright (c) 2015 The Regents of the University of California. All rights reserved. Permission is hereby granted, without written agreement and without license or royalty fees, to use, copy, modify, and distribute this software and its documentation for any purpose, provided that the above copyright notice and the following two paragraphs appear in all copies of this software. IN NO EVENT SHALL THE UNIVERSITY OF CALIFORNIA BE LIABLE TO ANY PARTY FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF THE UNIVERSITY OF CALIFORNIA HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. THE UNIVERSITY OF CALIFORNIA SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS ON AN "AS IS" BASIS, AND THE UNIVERSITY OF CALIFORNIA HAS NO OBLIGATION TO PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS. PT_COPYRIGHT_VERSION_2 COPYRIGHTENDKEY */ import javax.imageio.ImageIO; public class Main { /** Return an array of the types supported by the current host for * sendType arguments. */ public static String[] supportedSendTypes() { String[] imageTypes = ImageIO.getWriterFormatNames(); String[] result = new String[imageTypes.length + 2]; result[0] = "application/json"; result[1] = "text/plain"; System.arraycopy(imageTypes, 0, result, 2, imageTypes.length); return result; } }