001    /*
002     * Licensed to the Apache Software Foundation (ASF) under one
003     * or more contributor license agreements. See the NOTICE file
004     * distributed with this work for additional information
005     * regarding copyright ownership. The ASF licenses this file
006     * to you under the Apache License, Version 2.0 (the  "License");
007     * you may not use this file except in compliance with the License.
008     * You may obtain a copy of the License at
009     *
010     *     http://www.apache.org/licenses/LICENSE-2.0
011     *
012     * Unless required by applicable law or agreed to in writing, software
013     * distributed under the License is distributed on an "AS IS" BASIS,
014     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015     * See the License for the specific language governing permissions and
016     * limitations under the License.
017     */
018    /*
019     * $Id: WriterChain.java 468654 2006-10-28 07:09:23Z minchau $
020     */
021    package org.apache.xml.serializer;
022    
023    import java.io.IOException;
024    
025    /**
026     * It is unfortunate that java.io.Writer is a class rather than an interface.
027     * The serializer has a number of classes that extend java.io.Writer
028     * and which send their ouput to a yet another wrapped Writer or OutputStream.
029     * 
030     * The purpose of this interface is to force such classes to over-ride all of
031     * the important methods defined on the java.io.Writer class, namely these:
032     * <code>
033     * write(int val)
034     * write(char[] chars)
035     * write(char[] chars, int start, int count)
036     * write(String chars)
037     * write(String chars, int start, int count)
038     * flush()
039     * close()
040     * </code>
041     * In this manner nothing will accidentally go directly to 
042     * the base class rather than to the wrapped Writer or OutputStream. 
043     * 
044     * The purpose of this class is to have a uniform way of chaining the output of one writer to
045     * the next writer in the chain. In addition there are methods to obtain the Writer or 
046     * OutputStream that this object sends its output to.
047     * 
048     * This interface is only for internal use withing the serializer. 
049     * @xsl.usage internal
050     */
051    interface WriterChain
052    {
053        /** This method forces us to over-ride the method defined in java.io.Writer */
054        public void write(int val) throws IOException;
055        /** This method forces us to over-ride the method defined in java.io.Writer */
056        public void write(char[] chars) throws IOException;
057        /** This method forces us to over-ride the method defined in java.io.Writer */
058        public void write(char[] chars, int start, int count) throws IOException;
059        /** This method forces us to over-ride the method defined in java.io.Writer */
060        public void write(String chars) throws IOException;
061        /** This method forces us to over-ride the method defined in java.io.Writer */
062        public void write(String chars, int start, int count) throws IOException;
063        /** This method forces us to over-ride the method defined in java.io.Writer */
064        public void flush() throws IOException;
065        /** This method forces us to over-ride the method defined in java.io.Writer */
066        public void close() throws IOException;
067    
068        /**
069         * If this method returns null, getOutputStream() must return non-null.
070         * Get the writer that this writer sends its output to.
071         * 
072         * It is possible that the Writer returned by this method does not
073         * implement the WriterChain interface.
074         */
075        public java.io.Writer getWriter();
076        
077        /**
078         * If this method returns null, getWriter() must return non-null.
079         * Get the OutputStream that this writer sends its output to.
080         */
081        public java.io.OutputStream getOutputStream();
082    }