org.apache.wicket.request.Response.java Source code

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Here is the source code for org.apache.wicket.request.Response.java

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/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.apache.wicket.request;

import java.io.IOException;
import java.io.OutputStream;

import org.apache.wicket.util.lang.Args;

/**
 * Abstract base class for different implementations of response writing.
 * <p>
 * The implementation may not support calling both {@link #write(byte[])} and
 * {@link #write(CharSequence)} on the same {@link Response} instance.
 * 
 * @author Matej Knopp
 * @author igor.vaynberg
 */
public abstract class Response {
    /**
     * Writes the {@link CharSequence} to output.
     * 
     * @param sequence
     * @throws IllegalStateException
     *             if {@link #write(byte[])} has already been called on this instance
     */
    public abstract void write(CharSequence sequence);

    /**
     * Writes the buffer to output.
     * 
     * @param array
     *            the data.
     * @throws IllegalStateException
     *             if {@link #write(CharSequence)} has already been called on this instance
     */
    public abstract void write(byte[] array);

    /**
     * Writes the buffer to output.
     * 
     * @param array
     *            the data.
     * @param offset
     *            the start offset in the data.
     * @param length
     *            the number of bytes to write.
     * 
     * @throws IllegalStateException
     *             if {@link #write(CharSequence)} has already been called on this instance
     * @since 1.5.1
     */
    public abstract void write(byte[] array, int offset, int length);

    /**
     * Closes the response
     */
    public void close() {
    }

    /**
     * Encodes the specified URL by including the session ID in it, or, if encoding is not needed,
     * returns the URL unchanged.
     * 
     * @param url
     * @return encoded URL
     */
    public abstract String encodeURL(CharSequence url);

    /**
     * Called when the Response needs to reset itself. Subclasses can empty there buffer or build up
     * state.
     */
    public void reset() {
    }

    /**
     * Provides access to the low-level container response object that implementaion of this
     * {@link Response} delegate to. This allows users to access features provided by the container
     * response but not by generalized Wicket {@link Response} objects.
     * 
     * @return low-level container response object, or {@code null} if none
     */
    public abstract Object getContainerResponse();

    /**
     * Returns an {@link OutputStream} suitable for writing binary data in the response. The servlet
     * container does not encode the binary data.
     * 
     * <p>
     * Calling flush() on the OutputStream commits the response.
     * </p>
     * <p>
     * This method returns an output stream that delegates to {@link #write(byte[])},
     * {@link #write(byte[], int, int)}, and {@link #close()} methods of this response instance
     * </p>
     * 
     * @return output stream
     */
    public OutputStream getOutputStream() {
        return new StreamAdapter(this);
    }

    private static class StreamAdapter extends OutputStream {
        private final Response response;

        public StreamAdapter(Response response) {
            Args.notNull(response, "response");
            this.response = response;
        }

        @Override
        public void write(int b) throws IOException {
            response.write(new byte[] { (byte) b });
        }

        @Override
        public void write(byte[] b) throws IOException {
            response.write(b);
        }

        @Override
        public void write(byte[] b, int off, int len) throws IOException {
            response.write(b, off, len);
        }

        @Override
        public void close() throws IOException {
            super.close();
            response.close();
        }
    }

}