/* * Copyright 2013 Netflix, 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 feign; import java.lang.reflect.Array; import java.nio.charset.Charset; import java.util.ArrayList; import java.util.Collection; import java.util.Collections; import java.util.Map; import static java.lang.String.format; /** * Utilities, typically copied in from guava, so as to avoid dependency conflicts. */ public class Util { private Util() { // no instances } // feign.Util /** * The HTTP Accept header field name. */ public static final String ACCEPT = "Accept"; /** * The HTTP Content-Length header field name. */ public static final String CONTENT_LENGTH = "Content-Length"; /** * The HTTP Content-Type header field name. */ public static final String CONTENT_TYPE = "Content-Type"; /** * The HTTP Host header field name. */ public static final String HOST = "Host"; /** * The HTTP Location header field name. */ public static final String LOCATION = "Location"; /** * The HTTP Retry-After header field name. */ public static final String RETRY_AFTER = "Retry-After"; // com.google.common.base.Charsets /** * UTF-8: eight-bit UCS Transformation Format. */ public static final Charset UTF_8 = Charset.forName("UTF-8"); /** * Copy of {@code com.google.common.base.Preconditions#checkArgument}. */ public static void checkArgument(boolean expression, String errorMessageTemplate, Object... errorMessageArgs) { if (!expression) { throw new IllegalArgumentException( format(errorMessageTemplate, errorMessageArgs)); } } /** * Copy of {@code com.google.common.base.Preconditions#checkNotNull}. */ public static T checkNotNull(T reference, String errorMessageTemplate, Object... errorMessageArgs) { if (reference == null) { // If either of these parameters is null, the right thing happens anyway throw new NullPointerException( format(errorMessageTemplate, errorMessageArgs)); } return reference; } /** * Copy of {@code com.google.common.base.Preconditions#checkState}. */ public static void checkState(boolean expression, String errorMessageTemplate, Object... errorMessageArgs) { if (!expression) { throw new IllegalStateException( format(errorMessageTemplate, errorMessageArgs)); } } /** * Adapted from {@code com.google.common.base.Strings#emptyToNull}. */ public static String emptyToNull(String string) { return string == null || string.isEmpty() ? null : string; } public static String join(char separator, String... parts) { if (parts == null || parts.length == 0) return ""; StringBuilder to = new StringBuilder(); for (int i = 0; i < parts.length; i++) { to.append(parts[i]); if (i + 1 < parts.length) { to.append(separator); } } return to.toString(); } /** * Adapted from {@code com.google.common.base.Strings#emptyToNull}. */ public static T[] toArray(Iterable extends T> iterable, Class type) { Collection collection; if (iterable instanceof Collection) { collection = (Collection) iterable; } else { collection = new ArrayList(); for (T element : iterable) { collection.add(element); } } T[] array = (T[]) Array.newInstance(type, collection.size()); return collection.toArray(array); } /** * Returns an unmodifiable collection which may be empty, but is never null. */ public static Collection valuesOrEmpty(Map> map, String key) { return map.containsKey(key) ? map.get(key) : Collections.emptyList(); } public static T firstOrNull(Map> map, String key) { if (map.containsKey(key) && !map.get(key).isEmpty()) { return map.get(key).iterator().next(); } return null; } }