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
007     * "License"); you may not use this file except in compliance
008     * with the License.  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    package org.apache.hadoop.lib.wsrs;
020    
021    import org.apache.hadoop.lib.util.Check;
022    
023    import java.text.MessageFormat;
024    
025    public abstract class Param<T> {
026      protected T value;
027    
028      public T parseParam(String name, String str) {
029        Check.notNull(name, "name");
030        try {
031          return (str != null && str.trim().length() > 0) ? parse(str) : null;
032        } catch (Exception ex) {
033          throw new IllegalArgumentException(
034            MessageFormat.format("Parameter [{0}], invalid value [{1}], value must be [{2}]",
035                                 name, str, getDomain()));
036        }
037      }
038    
039      public T value() {
040        return value;
041      }
042    
043      protected void setValue(T value) {
044        this.value = value;
045      }
046    
047      protected abstract String getDomain();
048    
049      protected abstract T parse(String str) throws Exception;
050    
051      public String toString() {
052        return value.toString();
053      }
054    }