/*
* 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.smartandroid.sa.json;
/**
* 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.
*
* <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);
}