001    // Copyright 2004, 2005 The Apache Software Foundation
002    //
003    // Licensed under the Apache License, Version 2.0 (the "License");
004    // you may not use this file except in compliance with the License.
005    // You may obtain a copy of the License at
006    //
007    //     http://www.apache.org/licenses/LICENSE-2.0
008    //
009    // Unless required by applicable law or agreed to in writing, software
010    // distributed under the License is distributed on an "AS IS" BASIS,
011    // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
012    // See the License for the specific language governing permissions and
013    // limitations under the License.
014    
015    package org.apache.tapestry.util.io;
016    
017    import org.apache.tapestry.services.DataSqueezer;
018    
019    /**
020     * Interface which defines a class used to convert data for a specific Java type into a String
021     * format (squeeze it), or convert from a String back into a Java type (unsqueeze).
022     * <p>
023     * This interface is somewhat misnamed; this is more of the GoF Strategy pattern than GoF Adaptor
024     * pattern.
025     * 
026     * @author Howard Lewis Ship
027     */
028    
029    public interface SqueezeAdaptor
030    {
031        /**
032         * Returns one or more characters, each of which will be a prefix for this adaptor.
033         */
034    
035        public String getPrefix();
036    
037        /**
038         * Returns the class (or interface) which can be encoded by this adaptor.
039         */
040    
041        public Class getDataClass();
042    
043        /**
044         * Converts the data object into a String.
045         * 
046         * @throws IOException
047         *             if the object can't be converted.
048         */
049    
050        public String squeeze(DataSqueezer squeezer, Object data);
051    
052        /**
053         * Converts a String back into an appropriate object.
054         * 
055         * @throws IOException
056         *             if the String can't be converted.
057         */
058    
059        public Object unsqueeze(DataSqueezer squeezer, String string);
060    }