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Util.java
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154 lines (141 loc) · 4.55 KB
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/*
* 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> 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> T[] toArray(Iterable<? extends T> iterable, Class<T> type) {
Collection<T> collection;
if (iterable instanceof Collection) {
collection = (Collection<T>) iterable;
} else {
collection = new ArrayList<T>();
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 <T> Collection<T> valuesOrEmpty(Map<String, Collection<T>> map, String key) {
return map.containsKey(key) ? map.get(key) : Collections.<T>emptyList();
}
public static <T> T firstOrNull(Map<String, Collection<T>> map, String key) {
if (map.containsKey(key) && !map.get(key).isEmpty()) {
return map.get(key).iterator().next();
}
return null;
}
}