com.wl4g.component.common.remoting.standard.CacheControl Maven / Gradle / Ivy
/*
* Copyright 2017 ~ 2025 the original author or 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 com.wl4g.component.common.remoting.standard;
import java.util.concurrent.TimeUnit;
import com.wl4g.component.common.lang.StringUtils2;
/**
* A builder for creating "Cache-Control" HTTP response headers.
*
*
* Adding Cache-Control directives to HTTP responses can significantly improve
* the client experience when interacting with a web application. This builder
* creates opinionated "Cache-Control" headers with response directives only,
* with several use cases in mind.
*
*
* - Caching HTTP responses with
* {@code CacheControl cc = CacheControl.maxAge(1, TimeUnit.HOURS)} will result
* in {@code Cache-Control: "max-age=3600"}
* - Preventing cache with {@code CacheControl cc = CacheControl.noStore()}
* will result in {@code Cache-Control: "no-store"}
* - Advanced cases like
* {@code CacheControl cc = CacheControl.maxAge(1, TimeUnit.HOURS).noTransform().cachePublic()}
* will result in
* {@code Cache-Control: "max-age=3600, no-transform, public"}
*
*
*
* Note that to be efficient, Cache-Control headers should be written along HTTP
* validators such as "Last-Modified" or "ETag" headers.
*
* @see rfc7234
* section 5.2.2
* @see
* HTTP caching - Google developers reference
* @see Mark Nottingham's cache
* documentation
*/
public class CacheControl {
private long maxAge = -1;
private boolean noCache = false;
private boolean noStore = false;
private boolean mustRevalidate = false;
private boolean noTransform = false;
private boolean cachePublic = false;
private boolean cachePrivate = false;
private boolean proxyRevalidate = false;
private long staleWhileRevalidate = -1;
private long staleIfError = -1;
private long sMaxAge = -1;
/**
* Create an empty CacheControl instance.
*
* @see #empty()
*/
protected CacheControl() {
}
/**
* Return an empty directive.
*
* This is well suited for using other optional directives without
* "max-age", "no-cache" or "no-store".
*
* @return {@code this}, to facilitate method chaining
*/
public static CacheControl empty() {
return new CacheControl();
}
/**
* Add a "max-age=" directive.
*
* This directive is well suited for publicly caching resources, knowing
* that they won't change within the configured amount of time. Additional
* directives can be also used, in case resources shouldn't be cached
* ({@link #cachePrivate()}) or transformed ({@link #noTransform()}) by
* shared caches.
*
* In order to prevent caches to reuse the cached response even when it has
* become stale (i.e. the "max-age" delay is passed), the "must-revalidate"
* directive should be set ({@link #mustRevalidate()}
*
* @param maxAge
* the maximum time the response should be cached
* @param unit
* the time unit of the {@code maxAge} argument
* @return {@code this}, to facilitate method chaining
* @see rfc7234
* section 5.2.2.8
*/
public static CacheControl maxAge(long maxAge, TimeUnit unit) {
CacheControl cc = new CacheControl();
cc.maxAge = unit.toSeconds(maxAge);
return cc;
}
/**
* Add a "no-cache" directive.
*
* This directive is well suited for telling caches that the response can be
* reused only if the client revalidates it with the server. This directive
* won't disable cache altogether and may result with clients sending
* conditional requests (with "ETag", "If-Modified-Since" headers) and the
* server responding with "304 - Not Modified" status.
*
* In order to disable caching and minimize requests/responses exchanges,
* the {@link #noStore()} directive should be used instead of
* {@code #noCache()}.
*
* @return {@code this}, to facilitate method chaining
* @see rfc7234
* section 5.2.2.2
*/
public static CacheControl noCache() {
CacheControl cc = new CacheControl();
cc.noCache = true;
return cc;
}
/**
* Add a "no-store" directive.
*
* This directive is well suited for preventing caches (browsers and
* proxies) to cache the content of responses.
*
* @return {@code this}, to facilitate method chaining
* @see rfc7234
* section 5.2.2.3
*/
public static CacheControl noStore() {
CacheControl cc = new CacheControl();
cc.noStore = true;
return cc;
}
/**
* Add a "must-revalidate" directive.
*
* This directive indicates that once it has become stale, a cache MUST NOT
* use the response to satisfy subsequent requests without successful
* validation on the origin server.
*
* @return {@code this}, to facilitate method chaining
* @see rfc7234
* section 5.2.2.1
*/
public CacheControl mustRevalidate() {
this.mustRevalidate = true;
return this;
}
/**
* Add a "no-transform" directive.
*
* This directive indicates that intermediaries (caches and others) should
* not transform the response content. This can be useful to force caches
* and CDNs not to automatically gzip or optimize the response content.
*
* @return {@code this}, to facilitate method chaining
* @see rfc7234
* section 5.2.2.4
*/
public CacheControl noTransform() {
this.noTransform = true;
return this;
}
/**
* Add a "public" directive.
*
* This directive indicates that any cache MAY store the response, even if
* the response would normally be non-cacheable or cacheable only within a
* private cache.
*
* @return {@code this}, to facilitate method chaining
* @see rfc7234
* section 5.2.2.5
*/
public CacheControl cachePublic() {
this.cachePublic = true;
return this;
}
/**
* Add a "private" directive.
*
* This directive indicates that the response message is intended for a
* single user and MUST NOT be stored by a shared cache.
*
* @return {@code this}, to facilitate method chaining
* @see rfc7234
* section 5.2.2.6
*/
public CacheControl cachePrivate() {
this.cachePrivate = true;
return this;
}
/**
* Add a "proxy-revalidate" directive.
*
* This directive has the same meaning as the "must-revalidate" directive,
* except that it does not apply to private caches (i.e. browsers, HTTP
* clients).
*
* @return {@code this}, to facilitate method chaining
* @see rfc7234
* section 5.2.2.7
*/
public CacheControl proxyRevalidate() {
this.proxyRevalidate = true;
return this;
}
/**
* Add an "s-maxage" directive.
*
* This directive indicates that, in shared caches, the maximum age
* specified by this directive overrides the maximum age specified by other
* directives.
*
* @param sMaxAge
* the maximum time the response should be cached
* @param unit
* the time unit of the {@code sMaxAge} argument
* @return {@code this}, to facilitate method chaining
* @see rfc7234
* section 5.2.2.9
*/
public CacheControl sMaxAge(long sMaxAge, TimeUnit unit) {
this.sMaxAge = unit.toSeconds(sMaxAge);
return this;
}
/**
* Add a "stale-while-revalidate" directive.
*
* This directive indicates that caches MAY serve the response in which it
* appears after it becomes stale, up to the indicated number of seconds. If
* a cached response is served stale due to the presence of this extension,
* the cache SHOULD attempt to revalidate it while still serving stale
* responses (i.e. without blocking).
*
* @param staleWhileRevalidate
* the maximum time the response should be used while being
* revalidated
* @param unit
* the time unit of the {@code staleWhileRevalidate} argument
* @return {@code this}, to facilitate method chaining
* @see rfc5861
* section 3
*/
public CacheControl staleWhileRevalidate(long staleWhileRevalidate, TimeUnit unit) {
this.staleWhileRevalidate = unit.toSeconds(staleWhileRevalidate);
return this;
}
/**
* Add a "stale-if-error" directive.
*
* This directive indicates that when an error is encountered, a cached
* stale response MAY be used to satisfy the request, regardless of other
* freshness information.
*
* @param staleIfError
* the maximum time the response should be used when errors are
* encountered
* @param unit
* the time unit of the {@code staleIfError} argument
* @return {@code this}, to facilitate method chaining
* @see rfc5861
* section 4
*/
public CacheControl staleIfError(long staleIfError, TimeUnit unit) {
this.staleIfError = unit.toSeconds(staleIfError);
return this;
}
/**
* Return the "Cache-Control" header value.
*
* @return {@code null} if no directive was added, or the header value
* otherwise
*/
public String getHeaderValue() {
StringBuilder ccValue = new StringBuilder();
if (this.maxAge != -1) {
appendDirective(ccValue, "max-age=" + Long.toString(this.maxAge));
}
if (this.noCache) {
appendDirective(ccValue, "no-cache");
}
if (this.noStore) {
appendDirective(ccValue, "no-store");
}
if (this.mustRevalidate) {
appendDirective(ccValue, "must-revalidate");
}
if (this.noTransform) {
appendDirective(ccValue, "no-transform");
}
if (this.cachePublic) {
appendDirective(ccValue, "public");
}
if (this.cachePrivate) {
appendDirective(ccValue, "private");
}
if (this.proxyRevalidate) {
appendDirective(ccValue, "proxy-revalidate");
}
if (this.sMaxAge != -1) {
appendDirective(ccValue, "s-maxage=" + Long.toString(this.sMaxAge));
}
if (this.staleIfError != -1) {
appendDirective(ccValue, "stale-if-error=" + Long.toString(this.staleIfError));
}
if (this.staleWhileRevalidate != -1) {
appendDirective(ccValue, "stale-while-revalidate=" + Long.toString(this.staleWhileRevalidate));
}
String ccHeaderValue = ccValue.toString();
return (StringUtils2.isNoneBlank(ccHeaderValue) ? ccHeaderValue : null);
}
private void appendDirective(StringBuilder builder, String value) {
if (builder.length() > 0) {
builder.append(", ");
}
builder.append(value);
}
}