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.classification.InterfaceAudience;
022
023 import java.text.MessageFormat;
024
025 @InterfaceAudience.Private
026 public abstract class Param<T> {
027 private String name;
028 protected T value;
029
030 public Param(String name, T defaultValue) {
031 this.name = name;
032 this.value = defaultValue;
033 }
034
035 public String getName() {
036 return name;
037 }
038
039 public T parseParam(String str) {
040 try {
041 value = (str != null && str.trim().length() > 0) ? parse(str) : value;
042 } catch (Exception ex) {
043 throw new IllegalArgumentException(
044 MessageFormat.format("Parameter [{0}], invalid value [{1}], value must be [{2}]",
045 name, str, getDomain()));
046 }
047 return value;
048 }
049
050 public T value() {
051 return value;
052 }
053
054 protected abstract String getDomain();
055
056 protected abstract T parse(String str) throws Exception;
057
058 @Override
059 public String toString() {
060 return (value != null) ? value.toString() : "NULL";
061 }
062
063 }