Java tutorial
/* * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER. * * Copyright (c) 1997-2017 Oracle and/or its affiliates. All rights reserved. * * The contents of this file are subject to the terms of either the GNU * General Public License Version 2 only ("GPL") or the Common Development * and Distribution License("CDDL") (collectively, the "License"). You * may not use this file except in compliance with the License. You can * obtain a copy of the License at * https://oss.oracle.com/licenses/CDDL+GPL-1.1 * or LICENSE.txt. See the License for the specific * language governing permissions and limitations under the License. * * When distributing the software, include this License Header Notice in each * file and include the License file at LICENSE.txt. * * GPL Classpath Exception: * Oracle designates this particular file as subject to the "Classpath" * exception as provided by Oracle in the GPL Version 2 section of the License * file that accompanied this code. * * Modifications: * If applicable, add the following below the License Header, with the fields * enclosed by brackets [] replaced by your own identifying information: * "Portions Copyright [year] [name of copyright owner]" * * Contributor(s): * If you wish your version of this file to be governed by only the CDDL or * only the GPL Version 2, indicate your decision by adding "[Contributor] * elects to include this software in this distribution under the [CDDL or GPL * Version 2] license." If you don't indicate a single choice of license, a * recipient has the option to distribute your version of this file under * either the CDDL, the GPL Version 2 or to extend the choice of license to * its licensees as provided above. However, if you add GPL Version 2 code * and therefore, elected the GPL Version 2 license, then the option applies * only if the new code is made subject to such option by the copyright * holder. */ package javax.mail.util; import java.io.*; import javax.activation.*; import javax.mail.internet.*; /** * A DataSource backed by a byte array. The byte array may be * passed in directly, or may be initialized from an InputStream * or a String. * * @since JavaMail 1.4 * @author John Mani * @author Bill Shannon * @author Max Spivak */ public class ByteArrayDataSource implements DataSource { private byte[] data; // data private int len = -1; private String type; // content-type private String name = ""; static class DSByteArrayOutputStream extends ByteArrayOutputStream { public byte[] getBuf() { return buf; } public int getCount() { return count; } } /** * Create a ByteArrayDataSource with data from the * specified InputStream and with the specified MIME type. * The InputStream is read completely and the data is * stored in a byte array. * * @param is the InputStream * @param type the MIME type * @exception IOException errors reading the stream */ public ByteArrayDataSource(InputStream is, String type) throws IOException { DSByteArrayOutputStream os = new DSByteArrayOutputStream(); byte[] buf = new byte[8192]; int len; while ((len = is.read(buf)) > 0) os.write(buf, 0, len); this.data = os.getBuf(); this.len = os.getCount(); /* * ByteArrayOutputStream doubles the size of the buffer every time * it needs to expand, which can waste a lot of memory in the worst * case with large buffers. Check how much is wasted here and if * it's too much, copy the data into a new buffer and allow the * old buffer to be garbage collected. */ if (this.data.length - this.len > 256 * 1024) { this.data = os.toByteArray(); this.len = this.data.length; // should be the same } this.type = type; } /** * Create a ByteArrayDataSource with data from the * specified byte array and with the specified MIME type. * * @param data the data * @param type the MIME type */ public ByteArrayDataSource(byte[] data, String type) { this.data = data; this.type = type; } /** * Create a ByteArrayDataSource with data from the * specified String and with the specified MIME type. * The MIME type should include a <code>charset</code> * parameter specifying the charset to be used for the * string. If the parameter is not included, the * default charset is used. * * @param data the String * @param type the MIME type * @exception IOException errors reading the String */ public ByteArrayDataSource(String data, String type) throws IOException { String charset = null; try { ContentType ct = new ContentType(type); charset = ct.getParameter("charset"); } catch (ParseException pex) { // ignore parse error } charset = MimeUtility.javaCharset(charset); if (charset == null) charset = MimeUtility.getDefaultJavaCharset(); // XXX - could convert to bytes on demand rather than copying here this.data = data.getBytes(charset); this.type = type; } /** * Return an InputStream for the data. * Note that a new stream is returned each time * this method is called. * * @return the InputStream * @exception IOException if no data has been set */ @Override public InputStream getInputStream() throws IOException { if (data == null) throw new IOException("no data"); if (len < 0) len = data.length; return new SharedByteArrayInputStream(data, 0, len); } /** * Return an OutputStream for the data. * Writing the data is not supported; an <code>IOException</code> * is always thrown. * * @exception IOException always */ @Override public OutputStream getOutputStream() throws IOException { throw new IOException("cannot do this"); } /** * Get the MIME content type of the data. * * @return the MIME type */ @Override public String getContentType() { return type; } /** * Get the name of the data. * By default, an empty string ("") is returned. * * @return the name of this data */ @Override public String getName() { return name; } /** * Set the name of the data. * * @param name the name of this data */ public void setName(String name) { this.name = name; } }