]>
Commit | Line | Data |
---|---|---|
cfd903b6 MG |
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; | |
18 | ||
19 | /** | |
20 | * A strategy (or policy) definition that is used to decide whether or not a field or top-level | |
21 | * class should be serialized or deserialized as part of the JSON output/input. For serialization, | |
22 | * if the {@link #shouldSkipClass(Class)} method returns false then that class or field type | |
23 | * will not be part of the JSON output. For deserialization, if {@link #shouldSkipClass(Class)} | |
24 | * returns false, then it will not be set as part of the Java object structure. | |
25 | * | |
26 | * <p>The following are a few examples that shows how you can use this exclusion mechanism. | |
27 | * | |
28 | * <p><strong>Exclude fields and objects based on a particular class type:</strong> | |
29 | * <pre class="code"> | |
30 | * private static class SpecificClassExclusionStrategy implements ExclusionStrategy { | |
31 | * private final Class<?> excludedThisClass; | |
32 | * | |
33 | * public SpecificClassExclusionStrategy(Class<?> excludedThisClass) { | |
34 | * this.excludedThisClass = excludedThisClass; | |
35 | * } | |
36 | * | |
37 | * public boolean shouldSkipClass(Class<?> clazz) { | |
38 | * return excludedThisClass.equals(clazz); | |
39 | * } | |
40 | * | |
41 | * public boolean shouldSkipField(FieldAttributes f) { | |
42 | * return excludedThisClass.equals(f.getDeclaredClass()); | |
43 | * } | |
44 | * } | |
45 | * </pre> | |
46 | * | |
47 | * <p><strong>Excludes fields and objects based on a particular annotation:</strong> | |
48 | * <pre class="code"> | |
49 | * public @interface FooAnnotation { | |
50 | * // some implementation here | |
51 | * } | |
52 | * | |
53 | * // Excludes any field (or class) that is tagged with an "@FooAnnotation" | |
54 | * private static class FooAnnotationExclusionStrategy implements ExclusionStrategy { | |
55 | * public boolean shouldSkipClass(Class<?> clazz) { | |
56 | * return clazz.getAnnotation(FooAnnotation.class) != null; | |
57 | * } | |
58 | * | |
59 | * public boolean shouldSkipField(FieldAttributes f) { | |
60 | * return f.getAnnotation(FooAnnotation.class) != null; | |
61 | * } | |
62 | * } | |
63 | * </pre> | |
64 | * | |
65 | * <p>Now if you want to configure {@code Gson} to use a user defined exclusion strategy, then | |
66 | * the {@code GsonBuilder} is required. The following is an example of how you can use the | |
67 | * {@code GsonBuilder} to configure Gson to use one of the above sample: | |
68 | * <pre class="code"> | |
69 | * ExclusionStrategy excludeStrings = new UserDefinedExclusionStrategy(String.class); | |
70 | * Gson gson = new GsonBuilder() | |
71 | * .setExclusionStrategies(excludeStrings) | |
72 | * .create(); | |
73 | * </pre> | |
74 | * | |
75 | * <p>For certain model classes, you may only want to serialize a field, but exclude it for | |
76 | * deserialization. To do that, you can write an {@code ExclusionStrategy} as per normal; | |
77 | * however, you would register it with the | |
78 | * {@link GsonBuilder#addDeserializationExclusionStrategy(ExclusionStrategy)} method. | |
79 | * For example: | |
80 | * <pre class="code"> | |
81 | * ExclusionStrategy excludeStrings = new UserDefinedExclusionStrategy(String.class); | |
82 | * Gson gson = new GsonBuilder() | |
83 | * .addDeserializationExclusionStrategy(excludeStrings) | |
84 | * .create(); | |
85 | * </pre> | |
86 | * | |
87 | * @author Inderjeet Singh | |
88 | * @author Joel Leitch | |
89 | * | |
90 | * @see GsonBuilder#setExclusionStrategies(ExclusionStrategy...) | |
91 | * @see GsonBuilder#addDeserializationExclusionStrategy(ExclusionStrategy) | |
92 | * @see GsonBuilder#addSerializationExclusionStrategy(ExclusionStrategy) | |
93 | * | |
94 | * @since 1.4 | |
95 | */ | |
96 | public interface ExclusionStrategy { | |
97 | ||
98 | /** | |
99 | * @param f the field object that is under test | |
100 | * @return true if the field should be ignored; otherwise false | |
101 | */ | |
102 | public boolean shouldSkipField(FieldAttributes f); | |
103 | ||
104 | /** | |
105 | * @param clazz the class object that is under test | |
106 | * @return true if the class should be ignored; otherwise false | |
107 | */ | |
108 | public boolean shouldSkipClass(Class<?> clazz); | |
109 | } |