1 package org.apache.onami.logging.core;
2
3 /*
4 * Licensed to the Apache Software Foundation (ASF) under one
5 * or more contributor license agreements. See the NOTICE file
6 * distributed with this work for additional information
7 * regarding copyright ownership. The ASF licenses this file
8 * to you under the Apache License, Version 2.0 (the
9 * "License"); you may not use this file except in compliance
10 * with the License. You may obtain a copy of the License at
11 *
12 * http://www.apache.org/licenses/LICENSE-2.0
13 *
14 * Unless required by applicable law or agreed to in writing,
15 * software distributed under the License is distributed on an
16 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
17 * KIND, either express or implied. See the License for the
18 * specific language governing permissions and limitations
19 * under the License.
20 */
21
22 import static java.lang.String.format;
23 import static java.lang.reflect.Modifier.isFinal;
24
25 import java.lang.reflect.Field;
26
27 import com.google.inject.MembersInjector;
28 import com.google.inject.ProvisionException;
29
30 /**
31 * The abstract Logger injector implementation, takes care of injecting the
32 * concrete Logger implementation to the logged filed.
33 */
34 public abstract class AbstractLoggerInjector<L>
35 implements MembersInjector<L>
36 {
37
38 /**
39 * The logger field has to be injected.
40 */
41 private final Field field;
42
43 /**
44 * Creates a new Logger injector.
45 *
46 * @param field the logger field has to be injected.
47 */
48 public AbstractLoggerInjector( Field field )
49 {
50 this.field = field;
51 this.field.setAccessible(true);
52 }
53
54 /**
55 * {@inheritDoc}
56 */
57 public final void injectMembers( Object target )
58 {
59 if ( isFinal( field.getModifiers() ) )
60 {
61 return;
62 }
63
64 try
65 {
66 if ( field.get( target ) == null )
67 {
68 field.set( target, createLogger( target.getClass() ) );
69 }
70 }
71 catch ( Exception e )
72 {
73 throw new ProvisionException( format( "Impossible to set logger for field '%s', see nested exception: %s",
74 field, e.getMessage() ) );
75 }
76 }
77
78 /**
79 * Creates a new Logger implementation for the specified Class.
80 *
81 * @return a new Logger implementation.
82 */
83 protected abstract L createLogger(Class<?> klass);
84
85 }