Java example source code file (URLDataSource.java)

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Java - Java tags/keywords

inputstream, ioexception, net, network, outputstream, string, url, urlconnection, urldatasource

The URLDataSource.java Java example source code

/*
 * Copyright (c) 1997, 2005, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

package javax.activation;

import java.net.URL;
import java.net.URLConnection;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.IOException;

/**
 * The URLDataSource class provides an object that wraps a <code>URL
 * object in a DataSource interface. URLDataSource simplifies the handling
 * of data described by URLs within the JavaBeans Activation Framework
 * because this class can be used to create new DataHandlers. <i>NOTE: The
 * DataHandler object creates a URLDataSource internally,
 * when it is constructed with a URL.</i>
 *
 * @see javax.activation.DataSource
 * @see javax.activation.DataHandler
 *
 * @since 1.6
 */
public class URLDataSource implements DataSource {
    private URL url = null;
    private URLConnection url_conn = null;

    /**
     * URLDataSource constructor. The URLDataSource class will
     * not open a connection to the URL until a method requiring it
     * to do so is called.
     *
     * @param url The URL to be encapsulated in this object.
     */
    public URLDataSource(URL url) {
        this.url = url;
    }

    /**
     * Returns the value of the URL content-type header field.
     * It calls the URL's <code>URLConnection.getContentType method
     * after retrieving a URLConnection object.
     * <i>Note: this method attempts to call the openConnection
     * method on the URL. If this method fails, or if a content type is not
     * returned from the URLConnection, getContentType returns
     * "application/octet-stream" as the content type.</i>
     *
     * @return the content type.
     */
    public String getContentType() {
        String type = null;

        try {
            if (url_conn == null)
                url_conn = url.openConnection();
        } catch (IOException e) { }

        if (url_conn != null)
            type = url_conn.getContentType();

        if (type == null)
            type = "application/octet-stream";

        return type;
    }

    /**
     * Calls the <code>getFile method on the URL used to
     * instantiate the object.
     *
     * @return the result of calling the URL's getFile method.
     */
    public String getName() {
        return url.getFile();
    }

    /**
     * The getInputStream method from the URL. Calls the
     * <code>openStream method on the URL.
     *
     * @return the InputStream.
     */
    public InputStream getInputStream() throws IOException {
        return url.openStream();
    }

    /**
     * The getOutputStream method from the URL. First an attempt is
     * made to get the URLConnection object for the URL. If that
     * succeeds, the getOutputStream method on the URLConnection
     * is returned.
     *
     * @return the OutputStream.
     */
    public OutputStream getOutputStream() throws IOException {
        // get the url connection if it is available
        url_conn = url.openConnection();

        if (url_conn != null) {
            url_conn.setDoOutput(true);
            return url_conn.getOutputStream();
        } else
            return null;
    }

    /**
     * Return the URL used to create this DataSource.
     *
     * @return The URL.
     */
    public URL getURL() {
        return url;
    }
}