001// ***************************************************************************************************************************
002// * Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements.  See the NOTICE file *
003// * distributed with this work for additional information regarding copyright ownership.  The ASF licenses this file        *
004// * to you under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance            *
005// * with the License.  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 distributed under the License is distributed on an  *
010// * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the License for the        *
011// * specific language governing permissions and limitations under the License.                                              *
012// ***************************************************************************************************************************
013package org.apache.juneau.utils;
014
015import static org.apache.juneau.internal.StringUtils.*;
016
017import java.io.*;
018import java.text.*;
019
020import org.apache.juneau.*;
021
022/**
023 * An encapsulated MessageFormat-style string and arguments.
024 *
025 * <p>
026 * Useful for delayed serialization of arguments for logging.
027 * Message string will not be constructed until the <c>toString()</c> method is called.
028 */
029public class StringMessage implements CharSequence, Writable {
030
031   private final String pattern;
032   private final Object[] args;
033   private String results;
034
035   /**
036    * Constructor.
037    *
038    * @param pattern {@link MessageFormat}-style pattern.
039    * @param args Message arguments.
040    */
041   public StringMessage(String pattern, Object...args) {
042      this.pattern = pattern;
043      this.args = args;
044   }
045
046   @Override /* Writable */
047   public Writer writeTo(Writer w) throws IOException {
048      w.write(toString());
049      return w;
050   }
051
052   @Override /* Writable */
053   public String getMediaType() {
054      return null;
055   }
056
057   @Override /* CharSequence */
058   public char charAt(int index) {
059      return toString().charAt(index);
060   }
061
062   @Override /* CharSequence */
063   public int length() {
064      return toString().length();
065   }
066
067   @Override /* CharSequence */
068   public CharSequence subSequence(int start, int end) {
069      return toString().subSequence(start, end);
070   }
071
072   @Override /* Object */
073   public String toString() {
074      if (results == null)
075         results = format(pattern, args);
076      return results;
077   }
078}