+package de.halbekunst.juplo.cachecontrol;
+
+import de.halbekunst.juplo.cachecontrol.annotations.CacheSeconds;
+import de.halbekunst.juplo.cachecontrol.annotations.Accepts;
+import de.halbekunst.juplo.cachecontrol.annotations.LastModified;
+import de.halbekunst.juplo.cachecontrol.annotations.ETag;
+import java.lang.annotation.Annotation;
+import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Method;
+import java.util.Date;
+import java.util.Map;
+import java.util.Map.Entry;
+import java.util.TreeMap;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ *
+ * @author kai
+ */
+public class CacheControl {
+ private final static Logger log = LoggerFactory.getLogger(CacheControl.class);
+
+ public static final String HEADER_DATE = "Date";
+ public static final String HEADER_CACHE_CONTROL = "Cache-Control";
+ public static final String HEADER_LAST_MODIFIED = "Last-Modified";
+ public static final String HEADER_ETAG = "ETag";
+ public static final String HEADER_EXPIRES = "Expires";
+ public static final String HEADER_PRAGMA = "Pragma";
+ public static final String HEADER_IF_MODIFIED_SINCE = "If-Modified-Since";
+ public static final String HEADER_IF_NONE_MATCH = "If-None-Match";
+
+ private static final ThreadLocal<CacheMethodHandle> tl = new ThreadLocal<CacheMethodHandle>();
+
+ private Integer defaultCacheSeconds;
+ private Long defaultLastModified;
+
+
+ public void init(Object handler) throws Exception {
+ if (CacheControl.tl.get() == null)
+ CacheControl.tl.set(new ReflectionCacheMethodHandle(handler));
+ }
+
+ public boolean decorate(
+ HttpServletRequest request,
+ HttpServletResponse response,
+ Object handler
+ ) throws Exception
+ {
+ try {
+ CacheMethodHandle controller = CacheControl.tl.get();
+
+ /** Doppelte Ausführung verhindern... */
+ if (controller == null) {
+ /** Dekoration wurde bereits durchgeführt! */
+ return true;
+ }
+
+ /**
+ * Alle Antworten (insbesondere auch 304) sollen nach dem {@plainlink
+ * http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.18 RFC 2616,
+ * Abschnitt 14.18} einen Date-Header enthalten
+ */
+ response.setDateHeader(HEADER_DATE, controller.getTimestamp());
+
+ /** Besondere Maßnahmen für besondere HTTP-Status-Codes ?!? */
+ int status = controller.accepts(request);
+ switch (status) {
+ case HttpServletResponse.SC_OK: // 200
+ case HttpServletResponse.SC_NO_CONTENT: // 204
+ case HttpServletResponse.SC_PARTIAL_CONTENT: // 206
+ /** Normale Antwort! Antwort dekorieren... */
+ break;
+ case HttpServletResponse.SC_BAD_REQUEST: // 400
+ case HttpServletResponse.SC_UNAUTHORIZED: // 401
+ case HttpServletResponse.SC_PAYMENT_REQUIRED: // 402
+ case HttpServletResponse.SC_FORBIDDEN: // 403
+ case HttpServletResponse.SC_NOT_FOUND: // 404
+ case HttpServletResponse.SC_METHOD_NOT_ALLOWED: // 405
+ case HttpServletResponse.SC_NOT_ACCEPTABLE: // 406
+ case HttpServletResponse.SC_PROXY_AUTHENTICATION_REQUIRED: // 407
+ case HttpServletResponse.SC_REQUEST_TIMEOUT: // 408
+ case HttpServletResponse.SC_CONFLICT: // 409
+ case HttpServletResponse.SC_GONE: // 410
+ case HttpServletResponse.SC_LENGTH_REQUIRED: // 411
+ case HttpServletResponse.SC_PRECONDITION_FAILED: // 412
+ case HttpServletResponse.SC_REQUEST_ENTITY_TOO_LARGE: // 413
+ case HttpServletResponse.SC_REQUEST_URI_TOO_LONG: // 414
+ case HttpServletResponse.SC_UNSUPPORTED_MEDIA_TYPE: // 415
+ case HttpServletResponse.SC_REQUESTED_RANGE_NOT_SATISFIABLE: // 416
+ case HttpServletResponse.SC_INTERNAL_SERVER_ERROR: // 500
+ case HttpServletResponse.SC_NOT_IMPLEMENTED: // 501
+ case HttpServletResponse.SC_SERVICE_UNAVAILABLE: // 503
+ case HttpServletResponse.SC_HTTP_VERSION_NOT_SUPPORTED: // 505
+ /**
+ * Ein Fehlercode kann stellvertretend für den Handler gesendet werden,
+ * da im Fehlerfall eh keine weiteren Daten ausgegeben werden!
+ */
+ response.sendError(status);
+ return true;
+ default:
+ /**
+ * Es ist nicht klar, was der Handler noch machen wird/muss:
+ * Antwort nicht dekorieren und Kontroller an den Handler übergeben...
+ */
+ return false;
+ }
+
+ String url = null;
+ if (log.isDebugEnabled()) {
+ if (request.getQueryString() == null) {
+ url = request.getRequestURI();
+ }
+ else {
+ StringBuilder builder = new StringBuilder();
+ builder.append(request.getRequestURI());
+ builder.append('?');
+ builder.append(request.getQueryString());
+ url = builder.toString();
+ }
+ }
+
+ int cacheSeconds = controller.getCacheSeconds(request);
+ if (cacheSeconds < 1) {
+ log.debug("{}: caching disabled!", url);
+ response.setDateHeader(HEADER_DATE, controller.getTimestamp());
+ response.setDateHeader(HEADER_EXPIRES, 0);
+ response.addHeader(HEADER_PRAGMA, "no-cache");
+ response.addHeader(HEADER_CACHE_CONTROL, "private");
+ response.addHeader(HEADER_CACHE_CONTROL, "no-cache");
+ response.addHeader(HEADER_CACHE_CONTROL, "no-store");
+ response.addHeader(HEADER_CACHE_CONTROL, "max-age=0");
+ response.addHeader(HEADER_CACHE_CONTROL, "s-max-age=0");
+ return true;
+ }
+
+ long ifModifiedSince = -1;
+ try {
+ ifModifiedSince = request.getDateHeader(HEADER_IF_MODIFIED_SINCE);
+ }
+ catch (Exception e) {
+ log.error("Exception while fetching If-Modified-Since: {}", e);
+ }
+
+ long lastModified = controller.getLastModified(request);
+
+ /**
+ * Sicherstellen, dass der Wert keine Millisekunden enthält, da die
+ * Zeitangabe aus dem Modified-Since-Header keine Millisekunden enthalten
+ * kann und der Test unten dann stets fehlschlagen würde!
+ */
+ lastModified = lastModified - (lastModified % 1000);
+
+ String ifNoneMatch = request.getHeader(HEADER_IF_NONE_MATCH);
+ String eTag = controller.getETag(request);
+
+ /**
+ * 304-Antworten sollen nach dem {@plainlink
+ * http://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html#sec10.3.5 RFC
+ * 2616, Abschnitt 10.3.5} einen ETag-Header enthalten, wenn auch die
+ * 200-Antwort einen enthalten hätte.
+ */
+ if (eTag != null)
+ response.setHeader(HEADER_ETAG, eTag);
+
+
+ if (ifModifiedSince >= lastModified && lastModified > 0) {
+ /**
+ * request.getDateHeader liefert die Zeit als long, oder -1, wenn der
+ * Header nicht existiert. D.h., wenn "If-Modified-Since" nicht gesetzt
+ * ist, wird die komplette Seite ausgeliefert.
+ * Der zusätzliche Test, ob lastModified größer 0 ist, ist nötig, um
+ * Fehler auszuschließen, wenn die Implementierung von Cachable
+ * negative Werte für Last-Modified zurückliefert.
+ */
+ if (log.isDebugEnabled())
+ log.debug("{}: Not modified since {}", url, new Date(ifModifiedSince));
+
+ if (ifNoneMatch == null) {
+ /** Neue Anfrage oder HTTP/1.0 Client! */
+ log.debug("{}: ETag nicht gesetzt -> 304", url);
+ response.setStatus(HttpServletResponse.SC_NOT_MODIFIED);
+ return false;
+ }
+ }
+
+ if (ifNoneMatch != null && ifNoneMatch.equals(eTag)) {
+ log.debug("{}: ETag {} not changed -> 304 ", url, ifNoneMatch);
+ response.setStatus(HttpServletResponse.SC_NOT_MODIFIED);
+ return false;
+ }
+
+
+ log.debug("{}: first up!", url);
+
+ /** HTTP/1.1-Caching-Header richtig setzen!! */
+ response.setDateHeader(HEADER_LAST_MODIFIED, lastModified);
+
+ /** Cache-Control für HTTP/1.1-Clients generieren */
+ Map<String, String> cacheControl = new TreeMap<String, String>();
+
+ /**
+ * Wenn eins JSESSIONID in der URL enthalten ist, darf die Anfrage nur vom
+ * Browser gecached werden!
+ */
+ if (request.isRequestedSessionIdFromURL()) {
+ cacheControl.put("private", null);
+ }
+ else {
+ /**
+ * Hier muss nicht geprüft werden, ob cacheSeconds > 0 gilt, da in diesem
+ * Fall oben bereits No-Cache-Header generiert und <code>false</code>
+ * zurückgeliefert werden!
+ *
+ * Den Wert als <code>max-age</code> zu den Schlüssel-Wert-Paaren für den
+ * <code>Cache-Control</code>-Header hinzufügen und einen entsprechenden
+ * <code>Expires</code>-Header für HTTP/1.0-Clients setzen.
+ */
+ cacheControl.put("max-age", Integer.toString(cacheSeconds));
+ response.setDateHeader(HEADER_EXPIRES, (controller.getTimestamp() + (long) cacheSeconds * 1000));
+ }
+
+ /** Dem Handler die Gelegenheit geben, den Cache-Controll-Header anzupassen */
+ controller.cacheControl(request, cacheControl);
+
+
+ if (cacheControl.containsKey("private")) {
+ /**
+ * HTTP/1.0 Caches davon abhalten, die Ressource zu cachen (vgl.: RFC
+ * 2616, {@plainlink
+ * http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.9.3
+ * Abschnitt 14.9.3} und {@plainlink
+ * http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.32
+ * Abschnitt 14.32})
+ */
+ response.setDateHeader(HEADER_EXPIRES, 0l);
+ response.addHeader(HEADER_PRAGMA, "no-cache");
+ }
+
+ StringBuilder builder = new StringBuilder();
+ for (Entry<String, String> entry : cacheControl.entrySet()) {
+ builder.setLength(0);
+ builder.append(entry.getKey());
+ if (entry.getValue() != null) {
+ builder.append('=');
+ builder.append(entry.getValue());
+ }
+ response.addHeader(HEADER_CACHE_CONTROL, builder.toString());
+ }
+
+ return true;
+ }
+ finally {
+ /**
+ * Thread-Locale-Variable zurücksetzen, damit
+ * 1.) ein doppelter Aufruf dieser Methode pro Request erkannt werden kann
+ * 2.) der nächste Request nicht mit dem selben Handle weiterarbeitet
+ */
+ CacheControl.tl.set(null);
+ }
+ }
+
+ public void release() {
+ CacheControl.tl.set(null);
+ }
+
+
+ interface CacheMethodHandle {
+ long getTimestamp();
+ int accepts(HttpServletRequest request) throws Exception;
+ int getCacheSeconds(HttpServletRequest request) throws Exception;
+ long getLastModified(HttpServletRequest request) throws Exception;
+ String getETag(HttpServletRequest request) throws Exception;
+ void cacheControl(HttpServletRequest request, Map<String, String> cacheControlMap) throws Exception;
+ }
+
+ class DefaultCacheMethodHandle implements CacheMethodHandle {
+
+ long now = System.currentTimeMillis();
+ Integer cacheSeconds;
+ Long lastModified;
+ String eTag;
+
+
+ DefaultCacheMethodHandle() {
+ this.cacheSeconds = CacheControl.this.defaultCacheSeconds;
+ this.lastModified = CacheControl.this.defaultLastModified;
+ this.eTag = null;
+ }
+
+
+ @Override
+ public long getTimestamp() {
+ return now;
+ }
+
+ @Override
+ public int accepts(HttpServletRequest request) {
+ return HttpServletResponse.SC_OK;
+ }
+
+ @Override
+ public int getCacheSeconds(HttpServletRequest request) {
+ return cacheSeconds;
+ }
+
+ @Override
+ public long getLastModified(HttpServletRequest request) {
+ return lastModified;
+ }
+
+ @Override
+ public String getETag(HttpServletRequest request) {
+ return eTag;
+ }
+
+ @Override
+ public void cacheControl(HttpServletRequest request, Map<String, String> cacheControlMap) {
+ }
+ }
+
+ class ReflectionCacheMethodHandle implements CacheMethodHandle {
+
+ private Object handler;
+ private DefaultCacheMethodHandle defaults = new DefaultCacheMethodHandle();
+ private Method accepts, cacheSeconds, lastModified, eTag, cacheControl;
+ private boolean isAcceptsDefined, isCacheSecondsDefined, isLastModifiedDefined, isETagDefined, isCacheControlDefined;
+
+
+ ReflectionCacheMethodHandle(Object handler) throws NoSuchMethodException {
+ this.handler = handler;
+ /** Class-Level-Annotations auslesen */
+ for (Annotation annotation : handler.getClass().getAnnotations()) {
+ if (annotation.annotationType().equals(CacheSeconds.class)) {
+ defaults.cacheSeconds = ((CacheSeconds)annotation).value();
+ isCacheSecondsDefined = true;
+ continue;
+ }
+ if (annotation.annotationType().equals(LastModified.class)) {
+ defaults.lastModified = ((LastModified)annotation).value();
+ if (defaults.lastModified < 1) {
+ /**
+ * Ein Last-Modified-Header wurde angefordert, aber es wurde kein
+ * statischer Wert spezifiziert:
+ * globalen statischen Default-Wert benutzen!
+ */
+ defaults.lastModified = defaultLastModified;
+ }
+ isLastModifiedDefined = true;
+ continue;
+ }
+ if (annotation.annotationType().equals(ETag.class)) {
+ defaults.eTag = ((ETag)annotation).value();
+ isETagDefined = true;
+ continue;
+ }
+ }
+
+ /** Method-Level-Annotations auslesen */
+ for (Method method : handler.getClass().getMethods()) {
+ for (Annotation annotation : method.getAnnotations()) {
+ if (annotation.annotationType().equals(Accepts.class)) {
+ if (isAcceptsDefined)
+ throw new IllegalArgumentException("Die Annotation @Accept wurde in der Klasse " + handler.getClass().getSimpleName() + " mehrfach verwendet!");
+ accepts = method;
+ isAcceptsDefined = true;
+ continue;
+ }
+ if (annotation.annotationType().equals(CacheSeconds.class)) {
+ if (isCacheSecondsDefined)
+ throw new IllegalArgumentException("Die Annotation @CacheSeconds wurde in der Klasse " + handler.getClass().getSimpleName() + " mehrfach verwendet!");
+ cacheSeconds = method;
+ isCacheSecondsDefined = true;
+ continue;
+ }
+ if (annotation.annotationType().equals(LastModified.class)) {
+ if (isLastModifiedDefined)
+ throw new IllegalArgumentException("Die Annotation @LastModified wurde in der Klasse " + handler.getClass().getSimpleName() + " mehrfach verwendet!");
+ lastModified = method;
+ isLastModifiedDefined = true;
+ continue;
+ }
+ if (annotation.annotationType().equals(ETag.class)) {
+ if (isETagDefined)
+ throw new IllegalArgumentException("Die Annotation @ETag wurde in der Klasse " + handler.getClass().getSimpleName() + " mehrfach verwendet!");
+ eTag = method;
+ isETagDefined = true;
+ continue;
+ }
+ if (annotation.annotationType().equals(de.halbekunst.juplo.cachecontrol.annotations.CacheControl.class)) {
+ if (isCacheControlDefined)
+ throw new IllegalArgumentException("Die Annotation @CacheControl wurde in der Klasse " + handler.getClass().getSimpleName() + " mehrfach verwendet!");
+ cacheControl = method;
+ isCacheControlDefined = true;
+ continue;
+ }
+ }
+ }
+ }
+
+
+ @Override
+ public long getTimestamp() {
+ return defaults.now;
+ }
+
+ @Override
+ public int accepts(HttpServletRequest request)
+ throws IllegalAccessException,
+ IllegalArgumentException,
+ InvocationTargetException
+ {
+ if (accepts == null)
+ return defaults.accepts(request);
+ else
+ return (Integer)accepts.invoke(handler, request);
+ }
+
+ @Override
+ public int getCacheSeconds(HttpServletRequest request)
+ throws IllegalAccessException,
+ IllegalArgumentException,
+ InvocationTargetException
+ {
+ if (cacheSeconds == null)
+ return defaults.getCacheSeconds(request);
+ else
+ return (Integer)cacheSeconds.invoke(handler, request);
+ }
+
+ @Override
+ public long getLastModified(HttpServletRequest request)
+ throws IllegalAccessException,
+ IllegalArgumentException,
+ InvocationTargetException
+ {
+ if (lastModified == null)
+ return defaults.getLastModified(request);
+ else
+ return (Long)lastModified.invoke(handler, request);
+ }
+
+ @Override
+ public String getETag(HttpServletRequest request)
+ throws IllegalAccessException,
+ IllegalArgumentException,
+ InvocationTargetException
+ {
+ if (eTag == null)
+ return defaults.getETag(request);
+ else
+ return (String)eTag.invoke(handler, request);
+ }
+
+ @Override
+ public void cacheControl(
+ HttpServletRequest request,
+ Map<String, String> cacheControlMap
+ )
+ throws IllegalAccessException,
+ IllegalArgumentException,
+ InvocationTargetException
+ {
+ if (cacheControl == null)
+ defaults.cacheControl(request, cacheControlMap);
+ else
+ cacheControl.invoke(handler, request, cacheControlMap);
+ }
+ }
+
+
+ public void setDefaultCacheSeconds(Integer defaultCacheSeconds) {
+ this.defaultCacheSeconds = defaultCacheSeconds;
+ }
+
+ public void setDefaultLastModified(Long defaultLastModified) {
+ this.defaultLastModified = defaultLastModified;
+ }
+}
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