Part.java

/*
 * Part.java February 2007
 *
 * Copyright (C) 2007, Niall Gallagher <niallg@users.sf.net>
 *
 * 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.simpleframework.http;

import java.io.IOException;
import java.io.InputStream;

/**
 * The <code>Part</code> object is used to represent a part within a request
 * message. Typically a part represents either a text parameter or a file, with
 * associated headers. The contents of the part can be acquire as an
 * <code>InputStream</code> or as a string encoded in the default HTTP encoding
 * ISO-8859-1 or in the encoding specified with the Content-Type header.
 * 
 * @author Niall Gallagher
 */
public interface Part {

    /**
     * This method is used to determine the type of a part. Typically a part is
     * either a text parameter or a file. If this is true then the content
     * represented by the associated part is a file.
     * 
     * @return this returns true if the associated part is a file
     */
    boolean isFile();

    /**
     * This method is used to acquire the name of the part. Typically this is
     * used when the part represents a text parameter rather than a file.
     * However, this can also be used with a file part.
     * 
     * @return this returns the name of the associated part
     */
    String getName();

    /**
     * This method is used to acquire the file name of the part. This is used
     * when the part represents a text parameter rather than a file. However,
     * this can also be used with a file part.
     * 
     * @return this returns the file name of the associated part
     */
    String getFileName();

    /**
     * This is used to acquire the header value for the specified header name.
     * Providing the header values through this method ensures any special
     * processing for a know content type can be handled by an application.
     * 
     * @param name
     *            the name of the header to get the value for
     * 
     * @return value of the header mapped to the specified name
     */
    String getHeader(String name);

    /**
     * This is used to acquire the content of the part as a string. The encoding
     * of the string is taken from the content type. If no content type is sent
     * the content is decoded in the standard default of ISO-8859-1.
     * 
     * @return this returns a string representing the content
     * 
     * @throws IOException
     *             thrown if the content can not be created
     */
    String getContent() throws IOException;

    /**
     * This is used to acquire an <code>InputStream</code> for the part.
     * Acquiring the stream allows the content of the part to be consumed by
     * reading the stream. Each invocation of this method will produce a new
     * stream starting from the first byte.
     * 
     * @return this returns the stream for this part object
     * 
     * @throws IOException
     *             thrown if the stream can not be created
     */
    InputStream getInputStream() throws IOException;

    /**
     * This is used to acquire the content type for this part. This is typically
     * the type of content for a file part, as provided by a MIME type from the
     * HTTP "Content-Type" header.
     * 
     * @return this returns the content type for the part object
     */
    ContentType getContentType();
}