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 }