1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one
3 * or more contributor license agreements. See the NOTICE file
4 * distributed with this work for additional information
5 * regarding copyright ownership. The ASF licenses this file
6 * to you under the Apache License, Version 2.0 (the
7 * "License"); you may not use this file except in compliance
8 * with the License. You may obtain a copy of the License at
9 *
10 * http://www.apache.org/licenses/LICENSE-2.0
11 *
12 * Unless required by applicable law or agreed to in writing, software
13 * distributed under the License is distributed on an "AS IS" BASIS,
14 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15 * See the License for the specific language governing permissions and
16 * limitations under the License.
17 */
18
19 package org.apache.hadoop.chukwa.datacollection.agent;
20
21
22 import org.apache.hadoop.chukwa.datacollection.adaptor.Adaptor;
23 import org.apache.log4j.Logger;
24
25 /**
26 * Produces new unconfigured adaptors, given the class name of the appender type.
27 * Will try the name both in the default package, and then with
28 * 'org.apache.hadoop.chukwa.datacollection.adaptor' prepended.
29 *
30 */
31 public class AdaptorFactory {
32 public static final String PREPENDED_PACKAGE = "org.apache.hadoop.chukwa.datacollection.adaptor.";
33 static Logger log = Logger.getLogger(ChukwaAgent.class);
34
35 /**
36 * Instantiate an adaptor that can be added by the {@link ChukwaAgent}
37 *
38 * @param className the name of the {@link Adaptor} class to instantiate
39 * @return an Adaptor of the specified type
40 */
41 static public Adaptor createAdaptor(String className) {
42 Object obj = null;
43 try {
44 // the following reflection business for type checking is probably
45 // unnecessary
46 // since it will just throw a ClassCastException on error anyway.
47 obj = Class.forName(className).newInstance();
48 if (Adaptor.class.isInstance(obj)) {
49 return (Adaptor) obj;
50 } else
51 return null;
52 } catch (Exception e1) {
53 log.debug("Error instantiating new adaptor by class name, "
54 + "attempting again, but with default chukwa package prepended, i.e. "
55 + PREPENDED_PACKAGE + className
56 + ". " + e1);
57 try {
58 // if failed, try adding default class prefix
59 Object obj2 = Class.forName(
60 PREPENDED_PACKAGE + className)
61 .newInstance();
62 if (Adaptor.class.isInstance(obj2)) {
63 log.debug("Succeeded in finding class by adding default adaptor "
64 + "namespace prefix to class name profided");
65 return (Adaptor) obj2;
66 } else
67 return null;
68 } catch (Exception e2) {
69 log.warn("Error instantiating new adaptor "+ className + " by classname"
70 + " and also with \"o.a.h.c.datacollection.adaptor\" prefix added", e2);
71 return null;
72 }
73 }
74 }
75
76 }