View Javadoc
1   /*
2    * Copyright 2012 The Netty Project
3    *
4    * The Netty Project licenses this file to you under the Apache License,
5    * version 2.0 (the "License"); you may not use this file except in compliance
6    * with the License. You may obtain a copy of the License at:
7    *
8    *   http://www.apache.org/licenses/LICENSE-2.0
9    *
10   * Unless required by applicable law or agreed to in writing, software
11   * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
12   * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
13   * License for the specific language governing permissions and limitations
14   * under the License.
15   */
16  package io.netty.handler.codec.serialization;
17  
18  import io.netty.util.internal.PlatformDependent;
19  
20  import java.lang.ref.Reference;
21  import java.util.HashMap;
22  
23  public final class ClassResolvers {
24  
25      /**
26       * cache disabled
27       * @param classLoader - specific classLoader to use, or null if you want to revert to default
28       * @return new instance of class resolver
29       */
30      public static ClassResolver cacheDisabled(ClassLoader classLoader) {
31          return new ClassLoaderClassResolver(defaultClassLoader(classLoader));
32      }
33  
34      /**
35       * non-agressive non-concurrent cache
36       * good for non-shared default cache
37       *
38       * @param classLoader - specific classLoader to use, or null if you want to revert to default
39       * @return new instance of class resolver
40       */
41      public static ClassResolver weakCachingResolver(ClassLoader classLoader) {
42          return new CachingClassResolver(
43                  new ClassLoaderClassResolver(defaultClassLoader(classLoader)),
44                  new WeakReferenceMap<String, Class<?>>(new HashMap<String, Reference<Class<?>>>()));
45      }
46  
47      /**
48       * agressive non-concurrent cache
49       * good for non-shared cache, when we're not worried about class unloading
50       *
51       * @param classLoader - specific classLoader to use, or null if you want to revert to default
52       * @return new instance of class resolver
53       */
54      public static ClassResolver softCachingResolver(ClassLoader classLoader) {
55          return new CachingClassResolver(
56                  new ClassLoaderClassResolver(defaultClassLoader(classLoader)),
57                  new SoftReferenceMap<String, Class<?>>(new HashMap<String, Reference<Class<?>>>()));
58      }
59  
60      /**
61       * non-agressive concurrent cache
62       * good for shared cache, when we're worried about class unloading
63       *
64       * @param classLoader - specific classLoader to use, or null if you want to revert to default
65       * @return new instance of class resolver
66       */
67      public static ClassResolver weakCachingConcurrentResolver(ClassLoader classLoader) {
68          return new CachingClassResolver(
69                  new ClassLoaderClassResolver(defaultClassLoader(classLoader)),
70                  new WeakReferenceMap<String, Class<?>>(
71                          PlatformDependent.<String, Reference<Class<?>>>newConcurrentHashMap()));
72      }
73  
74      /**
75       * agressive concurrent cache
76       * good for shared cache, when we're not worried about class unloading
77       *
78       * @param classLoader - specific classLoader to use, or null if you want to revert to default
79       * @return new instance of class resolver
80       */
81      public static ClassResolver softCachingConcurrentResolver(ClassLoader classLoader) {
82          return new CachingClassResolver(
83                  new ClassLoaderClassResolver(defaultClassLoader(classLoader)),
84                  new SoftReferenceMap<String, Class<?>>(
85                          PlatformDependent.<String, Reference<Class<?>>>newConcurrentHashMap()));
86      }
87  
88      static ClassLoader defaultClassLoader(ClassLoader classLoader) {
89          if (classLoader != null) {
90              return classLoader;
91          }
92  
93          final ClassLoader contextClassLoader = PlatformDependent.getContextClassLoader();
94          if (contextClassLoader != null) {
95              return contextClassLoader;
96          }
97  
98          return PlatformDependent.getClassLoader(ClassResolvers.class);
99      }
100 
101     private ClassResolvers() {
102         // Unused
103     }
104 }