Part.java

/*
 * Copyright (C) 2013 Square, 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 retrofit2.http;

import java.lang.annotation.Documented;
import java.lang.annotation.Retention;
import java.lang.annotation.Target;
import retrofit2.Converter;

import static java.lang.annotation.ElementType.PARAMETER;
import static java.lang.annotation.RetentionPolicy.RUNTIME;

/**
 * Denotes a single part of a multi-part request.
 * <p>
 * The parameter type on which this annotation exists will be processed in one of three ways:
 * <ul>
 * <li>If the type is {@link okhttp3.MultipartBody.Part} the contents will be used directly. Omit
 * the name from the annotation (i.e., {@code @Part MultipartBody.Part part}).</li>
 * <li>If the type is {@link okhttp3.RequestBody RequestBody} the value will be used
 * directly with its content type. Supply the part name in the annotation (e.g.,
 * {@code @Part("foo") RequestBody foo}).</li>
 * <li>Other object types will be converted to an appropriate representation by using
 * {@linkplain Converter a converter}. Supply the part name in the annotation (e.g.,
 * {@code @Part("foo") Image photo}).</li>
 * </ul>
 * <p>
 * Values may be {@code null} which will omit them from the request body.
 * <p>
 * <pre><code>
 * @Multipart
 * @POST("/")
 * Call<ResponseBody> example(
 *     @Part("description") String description,
 *     @Part(value = "image", encoding = "8-bit") RequestBody image);
 * </code></pre>
 * <p>
 * Part parameters may not be {@code null}.
 */
@Documented
@Target(PARAMETER)
@Retention(RUNTIME)
public @interface Part {
  /**
   * The name of the part. Required for all parameter types except
   * {@link okhttp3.MultipartBody.Part}.
   */
  String value() default "";
  /** The {@code Content-Transfer-Encoding} of this part. */
  String encoding() default "binary";
}