1 /* 2 * Copyright (C) 2008 Google Inc. 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * 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, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package com.google.gson.annotations; 18 19 import com.google.gson.GsonBuilder; 20 import java.lang.annotation.Documented; 21 import java.lang.annotation.ElementType; 22 import java.lang.annotation.Retention; 23 import java.lang.annotation.RetentionPolicy; 24 import java.lang.annotation.Target; 25 26 /** 27 * An annotation that indicates the version number since a member or a type has been present. 28 * This annotation is useful to manage versioning of your JSON classes for a web-service. 29 * 30 * <p> 31 * This annotation has no effect unless you build {@link com.google.gson.Gson} with a 32 * {@code GsonBuilder} and invoke the {@link GsonBuilder#setVersion(double)} method. 33 * 34 * <p>Here is an example of how this annotation is meant to be used:</p> 35 * <pre> 36 * public class User { 37 * private String firstName; 38 * private String lastName; 39 * @Since(1.0) private String emailAddress; 40 * @Since(1.0) private String password; 41 * @Since(1.1) private Address address; 42 * } 43 * </pre> 44 * 45 * <p>If you created Gson with {@code new Gson()}, the {@code toJson()} and {@code fromJson()} 46 * methods will use all the fields for serialization and deserialization. However, if you created 47 * Gson with {@code Gson gson = new GsonBuilder().setVersion(1.0).create()} then the 48 * {@code toJson()} and {@code fromJson()} methods of Gson will exclude the {@code address} field 49 * since it's version number is set to {@code 1.1}.</p> 50 * 51 * @author Inderjeet Singh 52 * @author Joel Leitch 53 * @see GsonBuilder#setVersion(double) 54 * @see Until 55 */ 56 @Documented 57 @Retention(RetentionPolicy.RUNTIME) 58 @Target({ElementType.FIELD, ElementType.TYPE}) 59 public @interface Since { 60 /** 61 * The value indicating a version number since this member or type has been present. 62 * The number is inclusive; annotated elements will be included if {@code gsonVersion >= value}. 63 */ value()64 double value(); 65 } 66