container/catalina/src/share/org/apache/catalina/ssi/ResponseIncludeWrapper.java

/*
 * Copyright 1999,2004 The Apache Software Foundation. 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.apache.catalina.ssi;


import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpServletResponseWrapper;
/**
 * A HttpServletResponseWrapper, used from
 * <code>SSIServletExternalResolver</code>
 * 
 * @author Bip Thelin
 * @version $Revision$, $Date$
 */
public class ResponseIncludeWrapper extends HttpServletResponseWrapper {
    /**
     * Our ServletOutputStream
     */
    protected ServletOutputStream originalServletOutputStream;
    protected ServletOutputStream servletOutputStream;
    protected PrintWriter printWriter;


    /**
     * Initialize our wrapper with the current HttpServletResponse and
     * ServletOutputStream.
     * 
     * @param res
     *            The HttpServletResponse to use
     * @param out
     *            The ServletOutputStream' to use
     */
    public ResponseIncludeWrapper(HttpServletResponse res,
            ServletOutputStream originalServletOutputStream) {
        super(res);
        this.originalServletOutputStream = originalServletOutputStream;
    }


    /**
     * Flush the servletOutputStream or printWriter ( only one will be non-null )
     * This must be called after a requestDispatcher.include, since we can't
     * assume that the included servlet flushed its stream.
     */
    public void flushOutputStreamOrWriter() throws IOException {
        if (servletOutputStream != null) {
            servletOutputStream.flush();
        }
        if (printWriter != null) {
            printWriter.flush();
        }
    }


    /**
     * Return a printwriter, throws and exception if a OutputStream already
     * been returned.
     * 
     * @return a PrintWriter object
     * @exception java.io.IOException
     *                if the outputstream already been called
     */
    public PrintWriter getWriter() throws java.io.IOException {
        if (servletOutputStream == null) {
            if (printWriter == null) {
                printWriter = new PrintWriter(originalServletOutputStream);
            }
            return printWriter;
        }
        throw new IllegalStateException();
    }


    /**
     * Return a OutputStream, throws and exception if a printwriter already
     * been returned.
     * 
     * @return a OutputStream object
     * @exception java.io.IOException
     *                if the printwriter already been called
     */
    public ServletOutputStream getOutputStream() throws java.io.IOException {
        if (printWriter == null) {
            if (servletOutputStream == null) {
                servletOutputStream = originalServletOutputStream;
            }
            return servletOutputStream;
        }
        throw new IllegalStateException();
    }
}