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> 39 * This factory detects (via reflection) if the full (non-Lite) protocol buffer libraries 40 * are available, and if so, the instances returned are actually {@link ExtensionRegistry}. 41 */ 42 final class ExtensionRegistryFactory { 43 44 static final String FULL_REGISTRY_CLASS_NAME = "com.google.protobuf.ExtensionRegistry"; 45 46 /* Visible for Testing 47 @Nullable */ 48 static final Class<?> EXTENSION_REGISTRY_CLASS = reflectExtensionRegistry(); 49 50 /* @Nullable */ reflectExtensionRegistry()51 static Class<?> reflectExtensionRegistry() { 52 try { 53 return Class.forName(FULL_REGISTRY_CLASS_NAME); 54 } catch (ClassNotFoundException e) { 55 // The exception allocation is potentially expensive on Android (where it can be triggered 56 // many times at start up). Is there a way to ameliorate this? 57 return null; 58 } 59 } 60 61 /** Construct a new, empty instance. */ create()62 public static ExtensionRegistryLite create() { 63 if (EXTENSION_REGISTRY_CLASS != null) { 64 try { 65 return invokeSubclassFactory("newInstance"); 66 } catch (Exception e) { 67 // return a Lite registry. 68 } 69 } 70 return new ExtensionRegistryLite(); 71 } 72 73 /** Get the unmodifiable singleton empty instance. */ createEmpty()74 public static ExtensionRegistryLite createEmpty() { 75 if (EXTENSION_REGISTRY_CLASS != null) { 76 try { 77 return invokeSubclassFactory("getEmptyRegistry"); 78 } catch (Exception e) { 79 // return a Lite registry. 80 } 81 } 82 return EMPTY_REGISTRY_LITE; 83 } 84 isFullRegistry(ExtensionRegistryLite registry)85 static boolean isFullRegistry(ExtensionRegistryLite registry) { 86 return EXTENSION_REGISTRY_CLASS != null 87 && EXTENSION_REGISTRY_CLASS.isAssignableFrom(registry.getClass()); 88 } 89 invokeSubclassFactory(String methodName)90 private static final ExtensionRegistryLite invokeSubclassFactory(String methodName) 91 throws Exception { 92 return (ExtensionRegistryLite) EXTENSION_REGISTRY_CLASS 93 .getMethod(methodName).invoke(null); 94 } 95 } 96