1 // Protocol Buffers - Google's data interchange format 2 // Copyright 2008 Google Inc. All rights reserved. 3 // https://developers.google.com/protocol-buffers/ 4 // 5 // Redistribution and use in source and binary forms, with or without 6 // modification, are permitted provided that the following conditions are 7 // met: 8 // 9 // * Redistributions of source code must retain the above copyright 10 // notice, this list of conditions and the following disclaimer. 11 // * Redistributions in binary form must reproduce the above 12 // copyright notice, this list of conditions and the following disclaimer 13 // in the documentation and/or other materials provided with the 14 // distribution. 15 // * Neither the name of Google Inc. nor the names of its 16 // contributors may be used to endorse or promote products derived from 17 // this software without specific prior written permission. 18 // 19 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 20 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 21 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 22 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 23 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 24 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 25 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 26 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 27 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 28 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 29 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 30 31 package com.google.protobuf; 32 33 import static com.google.protobuf.ExtensionRegistryLite.EMPTY_REGISTRY_LITE; 34 35 /** 36 * A factory object to create instances of {@link ExtensionRegistryLite}. 37 * 38 * <p>This factory detects (via reflection) if the full (non-Lite) protocol buffer libraries are 39 * available, and if so, the instances returned are actually {@link ExtensionRegistry}. 40 */ 41 final class ExtensionRegistryFactory { 42 43 static final String FULL_REGISTRY_CLASS_NAME = "com.google.protobuf.ExtensionRegistry"; 44 45 /* Visible for Testing 46 @Nullable */ 47 static final Class<?> EXTENSION_REGISTRY_CLASS = reflectExtensionRegistry(); 48 reflectExtensionRegistry()49 static Class<?> reflectExtensionRegistry() { 50 try { 51 return Class.forName(FULL_REGISTRY_CLASS_NAME); 52 } catch (ClassNotFoundException e) { 53 // The exception allocation is potentially expensive on Android (where it can be triggered 54 // many times at start up). Is there a way to ameliorate this? 55 return null; 56 } 57 } 58 59 /** Construct a new, empty instance. */ create()60 public static ExtensionRegistryLite create() { 61 ExtensionRegistryLite result = invokeSubclassFactory("newInstance"); 62 63 return result != null ? result : new ExtensionRegistryLite(); 64 } 65 66 /** Get the unmodifiable singleton empty instance. */ createEmpty()67 public static ExtensionRegistryLite createEmpty() { 68 ExtensionRegistryLite result = invokeSubclassFactory("getEmptyRegistry"); 69 70 return result != null ? result : EMPTY_REGISTRY_LITE; 71 } 72 73 isFullRegistry(ExtensionRegistryLite registry)74 static boolean isFullRegistry(ExtensionRegistryLite registry) { 75 return EXTENSION_REGISTRY_CLASS != null 76 && EXTENSION_REGISTRY_CLASS.isAssignableFrom(registry.getClass()); 77 } 78 invokeSubclassFactory(String methodName)79 private static final ExtensionRegistryLite invokeSubclassFactory(String methodName) { 80 if (EXTENSION_REGISTRY_CLASS == null) { 81 return null; 82 } 83 84 try { 85 return (ExtensionRegistryLite) 86 EXTENSION_REGISTRY_CLASS.getDeclaredMethod(methodName).invoke(null); 87 } catch (Exception e) { 88 return null; 89 } 90 } 91 } 92