/* * Copyright 2012-2023 The Feign Authors * * 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 feign; import feign.template.UriUtils; import java.nio.charset.Charset; import java.util.Collection; /** * Various ways to encode collections in URL parameters. * *

* These specific cases are inspired by the OpenAPI * specification. *

*/ public enum CollectionFormat { /** Comma separated values, eg foo=bar,baz */ CSV(","), /** Space separated values, eg foo=bar baz */ SSV(" "), /** Tab separated values, eg foo=bar[tab]baz */ TSV("\t"), /** Values separated with the pipe (|) character, eg foo=bar|baz */ PIPES("|"), /** Parameter name repeated for each value, eg foo=bar&foo=baz */ // Using null as a special case since there is no single separator character EXPLODED(null); private final String separator; CollectionFormat(String separator) { this.separator = separator; } /** * Joins the field and possibly multiple values with the given separator. * *

* Calling EXPLODED.join("foo", ["bar"]) will return "foo=bar". *

* *

* Calling CSV.join("foo", ["bar", "baz"]) will return "foo=bar,baz". *

* *

* Null values are treated somewhat specially. With EXPLODED, the field is repeated without any * "=" for backwards compatibility. With all other formats, null values are not included in the * joined value list. *

* * @param field The field name corresponding to these values. * @param values A collection of value strings for the given field. * @param charset to encode the sequence * @return The formatted char sequence of the field and joined values. If the value collection is * empty, an empty char sequence will be returned. */ public CharSequence join(String field, Collection values, Charset charset) { StringBuilder builder = new StringBuilder(); int valueCount = 0; for (String value : values) { if (separator == null) { // exploded builder.append(valueCount++ == 0 ? "" : "&"); builder.append(UriUtils.encode(field, charset)); if (value != null) { builder.append('='); builder.append(value); } } else { // delimited with a separator character if (builder.length() == 0) { builder.append(UriUtils.encode(field, charset)); } if (value == null) { continue; } builder.append(valueCount++ == 0 ? "=" : UriUtils.encode(separator, charset)); builder.append(value); } } return builder; } }