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 49 /* @Nullable */ reflectExtensionRegistry()50 static Class<?> reflectExtensionRegistry() { 51 try { 52 return Class.forName(FULL_REGISTRY_CLASS_NAME); 53 } catch (ClassNotFoundException e) { 54 // The exception allocation is potentially expensive on Android (where it can be triggered 55 // many times at start up). Is there a way to ameliorate this? 56 return null; 57 } 58 } 59 60 /** Construct a new, empty instance. */ create()61 public static ExtensionRegistryLite create() { 62 ExtensionRegistryLite result = invokeSubclassFactory("newInstance"); 63 64 return result != null ? result : new ExtensionRegistryLite(); 65 } 66 67 /** Get the unmodifiable singleton empty instance. */ createEmpty()68 public static ExtensionRegistryLite createEmpty() { 69 ExtensionRegistryLite result = invokeSubclassFactory("getEmptyRegistry"); 70 71 return result != null ? result : EMPTY_REGISTRY_LITE; 72 } 73 74 isFullRegistry(ExtensionRegistryLite registry)75 static boolean isFullRegistry(ExtensionRegistryLite registry) { 76 return EXTENSION_REGISTRY_CLASS != null 77 && EXTENSION_REGISTRY_CLASS.isAssignableFrom(registry.getClass()); 78 } 79 80 /* @Nullable */ invokeSubclassFactory(String methodName)81 private static final ExtensionRegistryLite invokeSubclassFactory(String methodName) { 82 if (EXTENSION_REGISTRY_CLASS == null) { 83 return null; 84 } 85 86 try { 87 return (ExtensionRegistryLite) 88 EXTENSION_REGISTRY_CLASS.getDeclaredMethod(methodName).invoke(null); 89 } catch (Exception e) { 90 return null; 91 } 92 } 93 } 94