Move gson to its own folder

[unical.git] / gson / com / google / gson / ExclusionStrategy.java

diff --git a/gson/com/google/gson/ExclusionStrategy.java b/gson/com/google/gson/ExclusionStrategy.java
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+/*
+ * 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.
+ *
+ * <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&lt;?&gt; excludedThisClass;
+ *
+ *   public SpecificClassExclusionStrategy(Class&lt;?&gt; excludedThisClass) {
+ *     this.excludedThisClass = excludedThisClass;
+ *   }
+ *
+ *   public boolean shouldSkipClass(Class&lt;?&gt; 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 &#64interface FooAnnotation {
+ *   // some implementation here
+ * }
+ *
+ * // Excludes any field (or class) that is tagged with an "&#64FooAnnotation"
+ * private static class FooAnnotationExclusionStrategy implements ExclusionStrategy {
+ *   public boolean shouldSkipClass(Class&lt;?&gt; 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);
+}