85 lines
3.4 KiB
Java
85 lines
3.4 KiB
Java
/*
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* Copyright (C) 2008 Google Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.google.gson.annotations;
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import java.lang.annotation.Documented;
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import java.lang.annotation.ElementType;
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import java.lang.annotation.Retention;
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import java.lang.annotation.RetentionPolicy;
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import java.lang.annotation.Target;
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/**
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* An annotation that indicates this member should be exposed for JSON serialization or
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* deserialization.
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*
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* <p>This annotation has no effect unless you build {@link com.google.gson.Gson} with a {@link
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* com.google.gson.GsonBuilder} and invoke {@link
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* com.google.gson.GsonBuilder#excludeFieldsWithoutExposeAnnotation()} method.
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*
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* <p>Here is an example of how this annotation is meant to be used:
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*
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* <pre>
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* public class User {
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* @Expose private String firstName;
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* @Expose(serialize = false) private String lastName;
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* @Expose (serialize = false, deserialize = false) private String emailAddress;
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* private String password;
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* }
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* </pre>
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*
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* If you created Gson with {@code new Gson()}, the {@code toJson()} and {@code fromJson()} methods
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* will use the {@code password} field along-with {@code firstName}, {@code lastName}, and {@code
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* emailAddress} for serialization and deserialization. However, if you created Gson with {@code
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* Gson gson = new GsonBuilder().excludeFieldsWithoutExposeAnnotation().create()} then the {@code
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* toJson()} and {@code fromJson()} methods of Gson will exclude the {@code password} field. This is
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* because the {@code password} field is not marked with the {@code @Expose} annotation. Gson will
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* also exclude {@code lastName} and {@code emailAddress} from serialization since {@code serialize}
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* is set to {@code false}. Similarly, Gson will exclude {@code emailAddress} from deserialization
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* since {@code deserialize} is set to false.
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*
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* <p>Note that another way to achieve the same effect would have been to just mark the {@code
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* password} field as {@code transient}, and Gson would have excluded it even with default settings.
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* The {@code @Expose} annotation is useful in a style of programming where you want to explicitly
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* specify all fields that should get considered for serialization or deserialization.
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*
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* @author Inderjeet Singh
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* @author Joel Leitch
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*/
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@Documented
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@Retention(RetentionPolicy.RUNTIME)
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@Target(ElementType.FIELD)
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public @interface Expose {
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/**
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* If {@code true}, the field marked with this annotation is written out in the JSON while
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* serializing. If {@code false}, the field marked with this annotation is skipped from the
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* serialized output. Defaults to {@code true}.
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*
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* @since 1.4
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*/
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public boolean serialize() default true;
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/**
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* If {@code true}, the field marked with this annotation is deserialized from the JSON. If {@code
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* false}, the field marked with this annotation is skipped during deserialization. Defaults to
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* {@code true}.
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*
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* @since 1.4
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*/
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public boolean deserialize() default true;
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}
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