| 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 java.lang.annotation.ElementType; |
| 20 | import java.lang.annotation.Retention; |
| 21 | import java.lang.annotation.RetentionPolicy; |
| 22 | import java.lang.annotation.Target; |
| 23 | |
| 24 | /** |
| 25 | * An annotation that indicates the version number until a member or a type should be present. |
| 26 | * Basically, if Gson is created with a version number that exceeds the value stored in the |
| 27 | * {@code Until} annotation then the field will be ignored from the JSON output. This annotation |
| 28 | * 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 | * {@link com.google.gson.GsonBuilder} and invoke |
| 33 | * {@link com.google.gson.GsonBuilder#setVersion(double)} method. |
| 34 | * |
| 35 | * <p>Here is an example of how this annotation is meant to be used:</p> |
| 36 | * <pre> |
| 37 | * public class User { |
| 38 | * private String firstName; |
| 39 | * private String lastName; |
| 40 | * @Until(1.1) private String emailAddress; |
| 41 | * @Until(1.1) private String password; |
| 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(1.2).create()} then the |
| 48 | * {@code toJson()} and {@code fromJson()} methods of Gson will exclude the {@code emailAddress} |
| 49 | * and {@code password} fields from the example above, because the version number passed to the |
| 50 | * GsonBuilder, {@code 1.2}, exceeds the version number set on the {@code Until} annotation, |
| 51 | * {@code 1.1}, for those fields. |
| 52 | * |
| 53 | * @author Inderjeet Singh |
| 54 | * @author Joel Leitch |
| 55 | * @since 1.3 |
| 56 | */ |
| 57 | @Retention(RetentionPolicy.RUNTIME) |
| 58 | @Target({ElementType.FIELD, ElementType.TYPE}) |
| 59 | public @interface Until { |
| 60 | |
| 61 | /** |
| 62 | * the value indicating a version number until this member |
| 63 | * or type should be ignored. |
| 64 | */ |
| 65 | double value(); |
| 66 | } |