/* * 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 false then that class or field type * will not be part of the JSON output. For deserialization, if {@link #shouldSkipClass(Class)} * returns false, then it will not be set as part of the Java object structure. * *
The following are a few examples that shows how you can use this exclusion mechanism. * *
Exclude fields and objects based on a particular class type:
* Excludes fields and objects based on a particular annotation:
* 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
* ExclusionStrategy excludeStrings = new UserDefinedExclusionStrategy(String.class);
* Gson gson = new GsonBuilder()
* .setExclusionStrategies(excludeStrings)
* .create();
*
*
* @author Inderjeet Singh
* @author Joel Leitch
*
* @see GsonBuilder#setExclusionStrategies(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);
}
* private static class SpecificClassExclusionStrategy implements ExclusionStrategy {
* private final Class<?> excludedThisClass;
*
* public pecificClassExclusionStrategy(Class<?> excludedThisClass) {
* this.excludedThisClass = excludedThisClass;
* }
*
* public boolean shouldSkipClass(Class<?> clazz) {
* return excludedThisClass.equals(clazz);
* }
*
* public boolean shouldSkipField(FieldAttributes f) {
* return excludedThisClass.equals(f.getDeclaredClass());
* }
* }
*
*
*
* 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;
* }
* }
*
*
*