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Util.java
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/**
* Copyright 2012-2019 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 java.io.ByteArrayOutputStream;
import java.io.Closeable;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.Reader;
import java.lang.reflect.Array;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.lang.reflect.WildcardType;
import java.nio.Buffer;
import java.nio.ByteBuffer;
import java.nio.CharBuffer;
import java.nio.charset.CharacterCodingException;
import java.nio.charset.Charset;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.NoSuchElementException;
import java.util.Optional;
import java.util.Set;
import java.util.function.Predicate;
import java.util.function.Supplier;
import java.util.stream.Stream;
import static java.lang.String.format;
/**
* Utilities, typically copied in from guava, so as to avoid dependency conflicts.
*/
public class Util {
/**
* The HTTP Content-Length header field name.
*/
public static final String CONTENT_LENGTH = "Content-Length";
/**
* The HTTP Content-Encoding header field name.
*/
public static final String CONTENT_ENCODING = "Content-Encoding";
/**
* The HTTP Retry-After header field name.
*/
public static final String RETRY_AFTER = "Retry-After";
/**
* Value for the Content-Encoding header that indicates that GZIP encoding is in use.
*/
public static final String ENCODING_GZIP = "gzip";
/**
* Value for the Content-Encoding header that indicates that DEFLATE encoding is in use.
*/
public static final String ENCODING_DEFLATE = "deflate";
/**
* UTF-8: eight-bit UCS Transformation Format.
*/
public static final Charset UTF_8 = Charset.forName("UTF-8");
// com.google.common.base.Charsets
/**
* ISO-8859-1: ISO Latin Alphabet Number 1 (ISO-LATIN-1).
*/
public static final Charset ISO_8859_1 = Charset.forName("ISO-8859-1");
private static final int BUF_SIZE = 0x800; // 2K chars (4K bytes)
/**
* Type literal for {@code Map<String, ?>}.
*/
public static final Type MAP_STRING_WILDCARD =
new Types.ParameterizedTypeImpl(null, Map.class, String.class,
new Types.WildcardTypeImpl(new Type[] {Object.class}, new Type[0]));
private Util() { // no instances
}
/**
* 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));
}
}
/**
* Identifies a method as a default instance method.
*/
public static boolean isDefault(Method method) {
// Default methods are public non-abstract, non-synthetic, and non-static instance methods
// declared in an interface.
// method.isDefault() is not sufficient for our usage as it does not check
// for synthetic methods. As a result, it picks up overridden methods as well as actual default
// methods.
final int SYNTHETIC = 0x00001000;
return ((method.getModifiers()
& (Modifier.ABSTRACT | Modifier.PUBLIC | Modifier.STATIC | SYNTHETIC)) == Modifier.PUBLIC)
&& method.getDeclaringClass().isInterface();
}
/**
* Adapted from {@code com.google.common.base.Strings#emptyToNull}.
*/
public static String emptyToNull(String string) {
return string == null || string.isEmpty() ? null : string;
}
/**
* Removes values from the array that meet the criteria for removal via the supplied
* {@link Predicate} value
*/
@SuppressWarnings("unchecked")
public static <T> T[] removeValues(T[] values, Predicate<T> shouldRemove, Class<T> type) {
Collection<T> collection = new ArrayList<>(values.length);
for (T value : values) {
if (shouldRemove.negate().test(value)) {
collection.add(value);
}
}
T[] array = (T[]) Array.newInstance(type, collection.size());
return collection.toArray(array);
}
/**
* Adapted from {@code com.google.common.base.Strings#emptyToNull}.
*/
@SuppressWarnings("unchecked")
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) {
Collection<T> values = map.get(key);
return values != null ? values : Collections.emptyList();
}
public static void ensureClosed(Closeable closeable) {
if (closeable != null) {
try {
closeable.close();
} catch (IOException ignored) { // NOPMD
}
}
}
/**
* Resolves the last type parameter of the parameterized {@code supertype}, based on the {@code
* genericContext}, into its upper bounds.
* <p/>
* Implementation copied from {@code
* retrofit.RestMethodInfo}.
*
* @param genericContext Ex. {@link java.lang.reflect.Field#getGenericType()}
* @param supertype Ex. {@code Decoder.class}
* @return in the example above, the type parameter of {@code Decoder}.
* @throws IllegalStateException if {@code supertype} cannot be resolved into a parameterized type
* using {@code context}.
*/
public static Type resolveLastTypeParameter(Type genericContext, Class<?> supertype)
throws IllegalStateException {
Type resolvedSuperType =
Types.getSupertype(genericContext, Types.getRawType(genericContext), supertype);
checkState(resolvedSuperType instanceof ParameterizedType,
"could not resolve %s into a parameterized type %s",
genericContext, supertype);
Type[] types = ParameterizedType.class.cast(resolvedSuperType).getActualTypeArguments();
for (int i = 0; i < types.length; i++) {
Type type = types[i];
if (type instanceof WildcardType) {
types[i] = ((WildcardType) type).getUpperBounds()[0];
}
}
return types[types.length - 1];
}
/**
* This returns well known empty values for well-known java types. This returns null for types not
* in the following list.
*
* <ul>
* <li>{@code [Bb]oolean}</li>
* <li>{@code byte[]}</li>
* <li>{@code Collection}</li>
* <li>{@code Iterator}</li>
* <li>{@code List}</li>
* <li>{@code Map}</li>
* <li>{@code Set}</li>
* </ul>
*
* <p/>
* When {@link Feign.Builder#decode404() decoding HTTP 404 status}, you'll need to teach decoders
* a default empty value for a type. This method cheaply supports typical types by only looking at
* the raw type (vs type hierarchy). Decorate for sophistication.
*/
public static Object emptyValueOf(Type type) {
return EMPTIES.getOrDefault(Types.getRawType(type), () -> null).get();
}
private static final Map<Class<?>, Supplier<Object>> EMPTIES;
static {
final Map<Class<?>, Supplier<Object>> empties = new LinkedHashMap<Class<?>, Supplier<Object>>();
empties.put(boolean.class, () -> false);
empties.put(Boolean.class, () -> false);
empties.put(byte[].class, () -> new byte[0]);
empties.put(Collection.class, Collections::emptyList);
empties.put(Iterator.class, Collections::emptyIterator);
empties.put(List.class, Collections::emptyList);
empties.put(Map.class, Collections::emptyMap);
empties.put(Set.class, Collections::emptySet);
empties.put(Optional.class, Optional::empty);
empties.put(Stream.class, Stream::empty);
EMPTIES = Collections.unmodifiableMap(empties);
}
/**
* Adapted from {@code com.google.common.io.CharStreams.toString()}.
*/
public static String toString(Reader reader) throws IOException {
if (reader == null) {
return null;
}
try {
StringBuilder to = new StringBuilder();
CharBuffer charBuf = CharBuffer.allocate(BUF_SIZE);
// must cast to super class Buffer otherwise break when running with java 11
Buffer buf = charBuf;
while (reader.read(charBuf) != -1) {
buf.flip();
to.append(charBuf);
buf.clear();
}
return to.toString();
} finally {
ensureClosed(reader);
}
}
/**
* Adapted from {@code com.google.common.io.ByteStreams.toByteArray()}.
*/
public static byte[] toByteArray(InputStream in) throws IOException {
checkNotNull(in, "in");
try {
ByteArrayOutputStream out = new ByteArrayOutputStream();
copy(in, out);
return out.toByteArray();
} finally {
ensureClosed(in);
}
}
/**
* Adapted from {@code com.google.common.io.ByteStreams.copy()}.
*/
private static long copy(InputStream from, OutputStream to)
throws IOException {
checkNotNull(from, "from");
checkNotNull(to, "to");
byte[] buf = new byte[BUF_SIZE];
long total = 0;
while (true) {
int r = from.read(buf);
if (r == -1) {
break;
}
to.write(buf, 0, r);
total += r;
}
return total;
}
public static String decodeOrDefault(byte[] data, Charset charset, String defaultValue) {
if (data == null) {
return defaultValue;
}
checkNotNull(charset, "charset");
try {
return charset.newDecoder().decode(ByteBuffer.wrap(data)).toString();
} catch (CharacterCodingException ex) {
return defaultValue;
}
}
/**
* If the provided String is not null or empty.
*
* @param value to evaluate.
* @return true of the value is not null and not empty.
*/
public static boolean isNotBlank(String value) {
return value != null && !value.isEmpty();
}
/**
* If the provided String is null or empty.
*
* @param value to evaluate.
* @return true if the value is null or empty.
*/
public static boolean isBlank(String value) {
return value == null || value.isEmpty();
}
}