| /* |
| * Copyright (C) 2008 Google Inc. |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| package com.google.gson; |
| |
| /** |
| * A strategy (or policy) definition that is used to decide whether or not a field or top-level |
| * class should be serialized or deserialized as part of the JSON output/input. For serialization, |
| * if the {@link #shouldSkipClass(Class)} method returns true then that class or field type |
| * will not be part of the JSON output. For deserialization, if {@link #shouldSkipClass(Class)} |
| * returns true, then it will not be set as part of the Java object structure. |
| * |
| * <p>The following are a few examples that shows how you can use this exclusion mechanism. |
| * |
| * <p><strong>Exclude fields and objects based on a particular class type:</strong> |
| * <pre class="code"> |
| * private static class SpecificClassExclusionStrategy implements ExclusionStrategy { |
| * private final Class<?> excludedThisClass; |
| * |
| * public SpecificClassExclusionStrategy(Class<?> excludedThisClass) { |
| * this.excludedThisClass = excludedThisClass; |
| * } |
| * |
| * public boolean shouldSkipClass(Class<?> clazz) { |
| * return excludedThisClass.equals(clazz); |
| * } |
| * |
| * public boolean shouldSkipField(FieldAttributes f) { |
| * return excludedThisClass.equals(f.getDeclaredClass()); |
| * } |
| * } |
| * </pre> |
| * |
| * <p><strong>Excludes fields and objects based on a particular annotation:</strong> |
| * <pre class="code"> |
| * public @interface FooAnnotation { |
| * // some implementation here |
| * } |
| * |
| * // Excludes any field (or class) that is tagged with an "@FooAnnotation" |
| * private static class FooAnnotationExclusionStrategy implements ExclusionStrategy { |
| * public boolean shouldSkipClass(Class<?> clazz) { |
| * return clazz.getAnnotation(FooAnnotation.class) != null; |
| * } |
| * |
| * public boolean shouldSkipField(FieldAttributes f) { |
| * return f.getAnnotation(FooAnnotation.class) != null; |
| * } |
| * } |
| * </pre> |
| * |
| * <p>Now if you want to configure {@code Gson} to use a user defined exclusion strategy, then |
| * the {@code GsonBuilder} is required. The following is an example of how you can use the |
| * {@code GsonBuilder} to configure Gson to use one of the above sample: |
| * <pre class="code"> |
| * ExclusionStrategy excludeStrings = new UserDefinedExclusionStrategy(String.class); |
| * Gson gson = new GsonBuilder() |
| * .setExclusionStrategies(excludeStrings) |
| * .create(); |
| * </pre> |
| * |
| * <p>For certain model classes, you may only want to serialize a field, but exclude it for |
| * deserialization. To do that, you can write an {@code ExclusionStrategy} as per normal; |
| * however, you would register it with the |
| * {@link GsonBuilder#addDeserializationExclusionStrategy(ExclusionStrategy)} method. |
| * For example: |
| * <pre class="code"> |
| * ExclusionStrategy excludeStrings = new UserDefinedExclusionStrategy(String.class); |
| * Gson gson = new GsonBuilder() |
| * .addDeserializationExclusionStrategy(excludeStrings) |
| * .create(); |
| * </pre> |
| * |
| * @author Inderjeet Singh |
| * @author Joel Leitch |
| * |
| * @see GsonBuilder#setExclusionStrategies(ExclusionStrategy...) |
| * @see GsonBuilder#addDeserializationExclusionStrategy(ExclusionStrategy) |
| * @see GsonBuilder#addSerializationExclusionStrategy(ExclusionStrategy) |
| * |
| * @since 1.4 |
| */ |
| public interface ExclusionStrategy { |
| |
| /** |
| * @param f the field object that is under test |
| * @return true if the field should be ignored; otherwise false |
| */ |
| public boolean shouldSkipField(FieldAttributes f); |
| |
| /** |
| * @param clazz the class object that is under test |
| * @return true if the class should be ignored; otherwise false |
| */ |
| public boolean shouldSkipClass(Class<?> clazz); |
| } |