com.adaptris.transform.Source.java Source code

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Here is the source code for com.adaptris.transform.Source.java

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/*
 * Copyright 2015 Adaptris Ltd.
 * 
 * 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.adaptris.transform;

import java.io.IOException;
import java.io.Reader;
import java.net.URISyntaxException;

import org.apache.commons.lang.builder.EqualsBuilder;
import org.apache.commons.lang.builder.HashCodeBuilder;
import org.xml.sax.InputSource;

import com.adaptris.util.URLHelper;

/**
 * <p>An input to a transformation process may either be the data
 * source that is to be transformed or it may be the rules used to
 * govern the transformation.</p>
 *
 * <p>This class allows an application to encapsulate information
 * about an input to a transformation process in a single object.
 * This may include a <code>url</code> identifier, character stream,
 * byte stream or a SAX input source.</p>
 *
 * <p>Where a <code>url</code> identifier is used to initialise a
 * <code>Source</code>, it may represent a file on a local system
 * or it may point to a <code>url</code> resource on the web.
 * Note, that it is assumed by this class that any <code>url</code>
 * specified will be pointing at text data and that its encoding
 * will be the same as the default encoding of the client system.</p>
 *
 * <p>Some of the constructors and set methods have an additional
 * parameter specifying a <code>url</code> identifier. This is to get
 * around the fact that a parser has no way of resolving a relative
 * <code>url</code> that appears in a document source if a byte
 * stream or a character stream is being used. Consider that a
 * document source contains the following line: </p>
 *
 * <p align="center">
 * &lt;!DOCTYPE books SYSTEM "books.dtd"&gt;
 * </p>
 *
 * <p>The XML specification says that such a file should be found in
 * the same directory as the source document. But we do not have a
 * directory for the source document because it was in memory when
 * parsing started. To get around this, a <code>url</code> may be
 * supplied along with a byte stream or character stream. This
 * <code>url</code> is not used to read the source document, but
 * is used only as a base for resolving any relative <code>url</code>s
 * found in the source document.</p>
 *
 * <p>Note that the most recent set method, will unset the effect
 * of any previous set invocation. In other words repeated set
 * method invocations are not cumulative in their effect.</p>
 *
 * @author   Trevor Vaughan
 * @version  0.1 April 2001
 */
public class Source {

    private Reader charStream;
    private String url;

    // //////////////////////////////////////
    // constructors
    // //////////////////////////////////////

    public Source() {
    }

    /**
     * <p>Creates a new <code>Source</code> using a <code>url</code> string.
     * The input must be fully resolved.</p>
     *
     * <p>It is assumed that the <code>url</code> is pointing at text data and
     * that its encoding is the same as the default encoding of the client
     * system.</p>
     *
     * @param url the fully resolved url.
     */
    public Source(String url) {
        this();
        this.url = url;
    }

    /**
     * Creates a new <code>Source</code> using a character stream.
     *
     * @param charStream the input character stream.
     */
    public Source(Reader charStream) {
        this();
        this.charStream = charStream;
    }

    /**
     * <p>Returns the character stream representation for this
     * <code>Source</code>. If the object has not been initialised
     * with a character stream then <code>null</code> is returned.</p>
     *
     * 
     * @return a reader.
     */
    public Reader getCharStream() {
        return this.charStream;
    }

    public InputSource getInputSource() throws IOException, URISyntaxException {
        InputSource is = new InputSource();

        if (this.url != null) {
            is.setSystemId(this.url);
            is.setCharacterStream(this.charStream);
            is.setByteStream(URLHelper.connect(url));
        } else {
            is.setSystemId(this.url);
            is.setCharacterStream(this.charStream);
        }
        return is;
    }

    public boolean equals(Object obj) {
        if (obj == null) {
            return false;
        }
        if (obj == this) {
            return true;
        }
        if (obj instanceof Source) {
            Source rhs = (Source) obj;
            return new EqualsBuilder().append(getCharStream(), rhs.getCharStream()).append(url, rhs.url).isEquals();
        }
        return false;
    }

    /** 
     *  @see java.lang.Object#hashCode()
     */
    public int hashCode() {
        return new HashCodeBuilder(11, 17).append(getCharStream()).append(url).toHashCode();
    }

} // class Source