io.netty.handler.codec.http.EmptyHttpHeaders Maven / Gradle / Ivy
/*
* Copyright 2015 The Netty Project
*
* The Netty Project licenses this file to you 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:
*
* https://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 io.netty.handler.codec.http;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;
import java.util.Map.Entry;
import java.util.Set;
public class EmptyHttpHeaders extends HttpHeaders {
static final Iterator> EMPTY_CHARS_ITERATOR =
Collections.>emptyList().iterator();
public static final EmptyHttpHeaders INSTANCE = instance();
/**
* @see InstanceInitializer#EMPTY_HEADERS
* @deprecated Use {@link EmptyHttpHeaders#INSTANCE}
*
* This is needed to break a cyclic static initialization loop between {@link HttpHeaders} and {@link
* EmptyHttpHeaders}.
*/
@Deprecated
static EmptyHttpHeaders instance() {
return InstanceInitializer.EMPTY_HEADERS;
}
protected EmptyHttpHeaders() {
}
@Override
public String get(String name) {
return null;
}
@Override
public Integer getInt(CharSequence name) {
return null;
}
@Override
public int getInt(CharSequence name, int defaultValue) {
return defaultValue;
}
@Override
public Short getShort(CharSequence name) {
return null;
}
@Override
public short getShort(CharSequence name, short defaultValue) {
return defaultValue;
}
@Override
public Long getTimeMillis(CharSequence name) {
return null;
}
@Override
public long getTimeMillis(CharSequence name, long defaultValue) {
return defaultValue;
}
@Override
public List getAll(String name) {
return Collections.emptyList();
}
@Override
public List> entries() {
return Collections.emptyList();
}
@Override
public boolean contains(String name) {
return false;
}
@Override
public boolean isEmpty() {
return true;
}
@Override
public int size() {
return 0;
}
@Override
public Set names() {
return Collections.emptySet();
}
@Override
public HttpHeaders add(String name, Object value) {
throw new UnsupportedOperationException("read only");
}
@Override
public HttpHeaders add(String name, Iterable values) {
throw new UnsupportedOperationException("read only");
}
@Override
public HttpHeaders addInt(CharSequence name, int value) {
throw new UnsupportedOperationException("read only");
}
@Override
public HttpHeaders addShort(CharSequence name, short value) {
throw new UnsupportedOperationException("read only");
}
@Override
public HttpHeaders set(String name, Object value) {
throw new UnsupportedOperationException("read only");
}
@Override
public HttpHeaders set(String name, Iterable values) {
throw new UnsupportedOperationException("read only");
}
@Override
public HttpHeaders setInt(CharSequence name, int value) {
throw new UnsupportedOperationException("read only");
}
@Override
public HttpHeaders setShort(CharSequence name, short value) {
throw new UnsupportedOperationException("read only");
}
@Override
public HttpHeaders remove(String name) {
throw new UnsupportedOperationException("read only");
}
@Override
public HttpHeaders clear() {
throw new UnsupportedOperationException("read only");
}
@Override
public Iterator> iterator() {
return entries().iterator();
}
@Override
public Iterator> iteratorCharSequence() {
return EMPTY_CHARS_ITERATOR;
}
/**
* This class is needed to break a cyclic static initialization loop between {@link HttpHeaders} and
* {@link EmptyHttpHeaders}.
*/
@Deprecated
private static final class InstanceInitializer {
/**
* The instance is instantiated here to break the cyclic static initialization between {@link EmptyHttpHeaders}
* and {@link HttpHeaders}. The issue is that if someone accesses {@link EmptyHttpHeaders#INSTANCE} before
* {@link HttpHeaders#EMPTY_HEADERS} then {@link HttpHeaders#EMPTY_HEADERS} will be {@code null}.
*/
@Deprecated
private static final EmptyHttpHeaders EMPTY_HEADERS = new EmptyHttpHeaders();
private InstanceInitializer() {
}
}
}