Question

我想在我的Wicket应用程序中关闭序列化并将所有页面/会话信息存储在RAM中。我的应用程序用户数量非常少（一般为1）;我不需要集群部署;我需要在请求之间缓存一些不可序列化的数据。

有没有办法让Wicket不会自动尝试序列化我的页面/会话？我尝试了在https://cwiki.apache.org/confluence/display/WICKET/Page+Storage使用HttpSessionDataStore的建议，但它没有效果。我仍然得到这样的堆栈跟踪：

SEVERE: Error serializing object class com.prosc.safetynet.Administer [object=[Page class = com.prosc.safetynet.Administer, id = 0, render count = 1]]
org.apache.wicket.util.io.SerializableChecker$WicketNotSerializableException: Unable to serialize class: com.prosc.safetynet.SafetyNetSession$1
Field hierarchy is:
  0 [class=com.prosc.safetynet.Administer, path=0]
    java.lang.Object org.apache.wicket.Component.data [class=org.apache.wicket.model.CompoundPropertyModel]
      private java.lang.Object org.apache.wicket.model.CompoundPropertyModel.target [class=com.prosc.safetynet.SafetyNetSession$2]
        final com.prosc.safetynet.SafetyNetSession com.prosc.safetynet.SafetyNetSession$2.this$0 [class=com.prosc.safetynet.SafetyNetSession]
          private java.lang.Object com.prosc.safetynet.SafetyNetSession.tryAndSerializeMeBitch [class=com.prosc.safetynet.SafetyNetSession$1] <----- field that is not serializable
    at org.apache.wicket.util.io.SerializableChecker.internalCheck(SerializableChecker.java:395)
    at org.apache.wicket.util.io.SerializableChecker.check(SerializableChecker.java:374)
    at org.apache.wicket.util.io.SerializableChecker.checkFields(SerializableChecker.java:655)
    at org.apache.wicket.util.io.SerializableChecker.internalCheck(SerializableChecker.java:578)
    at org.apache.wicket.util.io.SerializableChecker.check(SerializableChecker.java:374)
    at org.apache.wicket.util.io.SerializableChecker.checkFields(SerializableChecker.java:655)
    at org.apache.wicket.util.io.SerializableChecker.internalCheck(SerializableChecker.java:578)
    at org.apache.wicket.util.io.SerializableChecker.check(SerializableChecker.java:374)
    at org.apache.wicket.util.io.SerializableChecker.checkFields(SerializableChecker.java:655)
    at org.apache.wicket.util.io.SerializableChecker.internalCheck(SerializableChecker.java:578)
    at org.apache.wicket.util.io.SerializableChecker.check(SerializableChecker.java:374)
    at org.apache.wicket.util.io.SerializableChecker.checkFields(SerializableChecker.java:655)
    at org.apache.wicket.util.io.SerializableChecker.internalCheck(SerializableChecker.java:578)
    at org.apache.wicket.util.io.SerializableChecker.check(SerializableChecker.java:374)
    at org.apache.wicket.util.io.SerializableChecker.writeObjectOverride(SerializableChecker.java:724)
    at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:326)
    at org.apache.wicket.serialize.java.JavaSerializer$CheckerObjectOutputStream.writeObjectOverride(JavaSerializer.java:258)
    at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:326)
    at org.apache.wicket.serialize.java.JavaSerializer.serialize(JavaSerializer.java:77)
    at org.apache.wicket.pageStore.DefaultPageStore.serializePage(DefaultPageStore.java:368)
    at org.apache.wicket.pageStore.DefaultPageStore.storePage(DefaultPageStore.java:146)
    at org.apache.wicket.page.PageStoreManager$PersistentRequestAdapter.storeTouchedPages(PageStoreManager.java:383)
    at org.apache.wicket.page.RequestAdapter.commitRequest(RequestAdapter.java:171)
    at org.apache.wicket.page.AbstractPageManager.commitRequest(AbstractPageManager.java:94)
    at org.apache.wicket.page.PageManagerDecorator.commitRequest(PageManagerDecorator.java:68)
    at org.apache.wicket.page.PageAccessSynchronizer$2.commitRequest(PageAccessSynchronizer.java:281)
    at org.apache.wicket.Application$2.onDetach(Application.java:1598)
    at org.apache.wicket.request.cycle.RequestCycleListenerCollection$3.notify(RequestCycleListenerCollection.java:99)
    at org.apache.wicket.request.cycle.RequestCycleListenerCollection$3.notify(RequestCycleListenerCollection.java:97)
    at org.apache.wicket.util.listener.ListenerCollection$1.notify(ListenerCollection.java:119)
    at org.apache.wicket.util.listener.ListenerCollection.reversedNotify(ListenerCollection.java:143)
    at org.apache.wicket.util.listener.ListenerCollection.reversedNotifyIgnoringExceptions(ListenerCollection.java:113)
    at org.apache.wicket.request.cycle.RequestCycleListenerCollection.onDetach(RequestCycleListenerCollection.java:95)
    at org.apache.wicket.request.cycle.RequestCycle.onDetach(RequestCycle.java:603)
    at org.apache.wicket.request.cycle.RequestCycle.detach(RequestCycle.java:542)
    at org.apache.wicket.request.cycle.RequestCycle.processRequestAndDetach(RequestCycle.java:287)
    at org.apache.wicket.protocol.http.WicketFilter.processRequest(WicketFilter.java:188)
    at org.apache.wicket.protocol.http.WicketFilter.doFilter(WicketFilter.java:244)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:215)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:188)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:210)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:174)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:117)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:108)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:151)
    at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:870)
    at org.apache.coyote.http11.Http11BaseProtocol$Http11ConnectionHandler.processConnection(Http11BaseProtocol.java:665)
    at org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:528)
    at org.apache.tomcat.util.net.LeaderFollowerWorkerThread.runIt(LeaderFollowerWorkerThread.java:81)
    at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:685)
    at java.lang.Thread.run(Thread.java:680)

Answer 1

您可以实现自己的IPageStore，将页面保留在内存中。

Answer 2

我不能对Wicket的任何特定内容发表评论，但一般来说，Http Session的全部意义是在请求之间存储Serializable状态（并且在集群环境中，允许该状态为复制到群集中的多个节点，以便在节点发生故障时提供冗余）。将 not Serializable中的内容放入其中通常被视为错误，如堆栈跟踪所示。如果有任何类型的配置选项可以改变这一点，我会感到有些惊讶（尽管可能存在;正如我所说，我无法真正评论Wicket方面的事情）。

一个简单的替代方案，如果您不需要真正的持久性，并且数据不是特别大/复杂，那么只需使用页面上的隐藏表单字段来跟踪相关状态。

但是，如果您想要的是内存缓存，为什么不实现自己的？这很简单：

public class SessionCache {
    private static final Map<String, Map<String, Object>> CACHE = Collections.synchronizedMap(new HashMap<String, Map<String, Object>>());

    public static Object getAttribute(String sessionId, String attribName) {
        Map<String, Object> attribs = CACHE.get(sessionId);
        if (attribs != null) {
            synchronized(attribs) {
                return attribs.get(attribName);
            }
        }

        return null;
    }

    public static void setAttribute(String sessionId, String attribName, Object attribValue) {
        Map<String, Object> attribs = CACHE.get(sessionId);
        if (attribs == null) {
            attribs = new HashMap<String, Object>();
            CACHE.put(sessionId, attribs);
        }

        synchronized(attribs) {
            attribs.put(attribName, attribValue);
        }
    }

    public static void destroySession(String sessionId) {
        CACHE.remove(sessionId);
    }

    public static void createSession(String sessionId, boolean force) {
        if (force || ! CACHE.containsKey(sessionId)) {
            CACHE.put(sessionId, new HashMap<String, Object>());
        }
    }
}

请注意，您需要将其挂钩到Wicket的会话生命周期中，以便旧会话在到期时被删除。否则你手上会有逐渐的内存泄漏。从文档中看，您可以使用HttpSessionStore类上的registerUnboundListener()来完成此操作。

Answer 3

根据svenmeier的回答，这是我提出的解决方案。我确信这不是100％正确，但它在我的测试中运行良好：

package com.prosc.wicket;

import org.apache.wicket.Application;
import org.apache.wicket.DefaultPageManagerProvider;
import org.apache.wicket.page.IManageablePage;
import org.apache.wicket.page.IPageManagerContext;
import org.apache.wicket.pageStore.IDataStore;
import org.apache.wicket.pageStore.IPageStore;
import org.apache.wicket.pageStore.memory.HttpSessionDataStore;
import org.apache.wicket.pageStore.memory.PageNumberEvictionStrategy;

import java.io.Serializable;
import java.util.HashMap;
import java.util.Map;

/**
 * This class disables Wicket's serialization behavior, while still retaining session and page data in memory (so back button will work).
 * This will run out of memory under heavy load; but it's very convenient for low volume web applications.
 * To disable serialization in your application, call this code:
 * <pre>
 *     setPageManagerProvider( new NoSerializePageManagerProvider( this, getPageManagerContext() ) );
 * </pre>
 */
public class NoSerializePageManagerProvider extends DefaultPageManagerProvider {
    private IPageManagerContext pageManagerContext;

    public NoSerializePageManagerProvider( Application application, IPageManagerContext pageManagerContext ) {
        super( application );
        this.pageManagerContext = pageManagerContext;
    }

    @Override
    protected IDataStore newDataStore() {
        return new HttpSessionDataStore( pageManagerContext, new PageNumberEvictionStrategy( 20 ) );
    }

    @Override
    protected IPageStore newPageStore( IDataStore dataStore ) {
        return new IPageStore() {
            Map<String,Map<Integer,IManageablePage>> cache = new HashMap<String, Map<Integer, IManageablePage>>();

            public void destroy() {
                cache = null;
            }

            public IManageablePage getPage( String sessionId, int pageId ) {
                Map<Integer, IManageablePage> sessionCache = getSessionCache( sessionId, false );
                IManageablePage page = sessionCache.get( pageId );
                if( page == null ) {
                    throw new IllegalArgumentException( "Found this session, but there is no page with id " + pageId );
                }
                return page;
            }

            public void removePage( String sessionId, int pageId ) {
                getSessionCache( sessionId, false ).remove( pageId );
            }

            public void storePage( String sessionId, IManageablePage page ) {
                getSessionCache( sessionId, true ).put( page.getPageId(), page );
            }

            public void unbind( String sessionId ) {
                cache.remove( sessionId );
            }

            public Serializable prepareForSerialization( String sessionId, Object page ) {
                return null;
            }

            public Object restoreAfterSerialization( Serializable serializable ) {
                return null;
            }

            public IManageablePage convertToPage( Object page ) {
                return (IManageablePage)page;
            }

            private Map<Integer, IManageablePage> getSessionCache( String sessionId, boolean create ) {
                Map<Integer, IManageablePage> sessionCache = cache.get( sessionId );
                if( sessionCache == null ) {
                    if( create ) {
                        sessionCache = new HashMap<Integer, IManageablePage>();
                        cache.put( sessionId, sessionCache );
                    } else {
                        throw new IllegalArgumentException( "There are no pages stored for session id " + sessionId );
                    }
                }
                return sessionCache;
            }
        };
    }
}

Answer 4

我想改善Jesse的答案。下面是一个线程安全的IPageStore实现，内部＆＃34;最近最少插入＆＃34;缓存（每个会话最多保留5个最近访问的有状态页面）：

public class CustomPageStore implements IPageStore {

private static final Logger logger = LoggerFactory.getLogger(CustomPageStore.class);

private static final int MEDIAN_OF_NUMBER_OF_SESSIONS = 6000;

private ConcurrentMap<String, CustomLinkedHashMap<Integer, IManageablePage>> cache = new ConcurrentHashMap<>(MEDIAN_OF_NUMBER_OF_SESSIONS);

@Override
public void destroy() {
    cache.clear();
}

@Override
public IManageablePage getPage(final String sessionId, int pageId) {
    final Map<Integer, IManageablePage> sessionCache = getSessionCache(sessionId);
    final RequestCycle requestCycle = RequestCycle.get();
    if (sessionCache == null) {
        logger.warn("Missing cache. SessionId: {}, pageId: {}, URL: {}", sessionId, pageId, requestCycle == null ? StringUtils.EMPTY : requestCycle.getRequest().getUrl());
        return null;
    }

    final IManageablePage page;
    //noinspection SynchronizationOnLocalVariableOrMethodParameter
    synchronized (sessionCache) {
        page = sessionCache.get(pageId);
    }

    if (page == null && logger.isDebugEnabled()) {
        logger.debug("Missed page. SessionId: {}, pageId: {}, URL: {}", sessionId, pageId, requestCycle == null ? StringUtils.EMPTY : requestCycle.getRequest().getUrl());
    }

    return page;
}

@Override
public void removePage(final String sessionId, int pageId) {
    final Map<Integer, IManageablePage> sessionCache = getSessionCache(sessionId);
    if (sessionCache != null) {
        //noinspection SynchronizationOnLocalVariableOrMethodParameter
        synchronized (sessionCache) {
            sessionCache.remove(pageId);
        }
    }
}

@Override
public void storePage(final String sessionId, IManageablePage page) {
    final LinkedHashMap<Integer, IManageablePage> sessionCache = getOrCreateSessionCache(sessionId);
    final int pageId = page.getPageId();
    //noinspection SynchronizationOnLocalVariableOrMethodParameter
    synchronized (sessionCache) {
        if (sessionCache.containsKey(pageId)) {
            // do this to change insertion order and update least inserted entry
            sessionCache.remove(pageId);
            sessionCache.put(pageId, page);
        } else {
            sessionCache.put(pageId, page);
        }
    }
}

@Override
public void unbind(final String sessionId) {
    cache.remove(sessionId);
}

@Override
public Serializable prepareForSerialization(String sessionId, Object page) {
    return null;
}

@Override
public Object restoreAfterSerialization(Serializable serializable) {
    return null;
}

@Override
public IManageablePage convertToPage(final Object page) {
    return (IManageablePage) page;
}

@Nullable
private Map<Integer, IManageablePage> getSessionCache(final String sessionId) {
    return cache.get(sessionId);
}

@Nonnull
private CustomLinkedHashMap<Integer, IManageablePage> getOrCreateSessionCache(final String sessionId) {
    return cache.computeIfAbsent(sessionId, s -> new CustomLinkedHashMap<>());
}

/** Mimics "least recently inserted" cache */
private static class CustomLinkedHashMap<K, V> extends LinkedHashMap<K, V> {

    /** use this parameter to control memory consumption and frequency of appearance of PageExpiredException */
    private static final int MAX_PAGES_PER_SESSION = 5;

    @Override
    protected boolean removeEldestEntry(final Map.Entry<K, V> eldest) {
        return size() > MAX_PAGES_PER_SESSION;
    }
}
}

Answer 5

我想改善约翰尼的答案，谁要改善杰西的答案：）

这是整个IPageManagerProvider，而不仅仅是IPageStore
通过调用store.unbind(sessionId)释放内存
还可以与Wicket 7.x一起使用

public class NoSerializationButCachingPageManagerProvider implements IPageManagerProvider {

    private static final Logger LOGGER = LoggerFactory.getLogger(NoSerializationButCachingPageManagerProvider.class);

    private final Application application;

    public NoSerializationButCachingPageManagerProvider(final Application application) {
        this.application = Args.notNull(application, "application");
        LOGGER.info("Pages don't get serialized, but in-memory cached.");
    }

    @Override
    public IPageManager get(IPageManagerContext pageManagerContext) {
        final IPageStore store = new NoSerializationButCachingPageStore();
        final IPageManager manager = new PageStoreManager(application.getName(), store, pageManagerContext);
        /*
         * session unbind must call store.unbind() to free memory (prevents memory leak)
         */
        application.getSessionStore().registerUnboundListener((String sessionId) -> store.unbind(sessionId));
        return manager;
    }

}

class NoSerializationButCachingPageStore implements IPageStore {

    private static final Logger LOGGER = LoggerFactory.getLogger(NoSerializationButCachingPageStore.class);

    private static final int MEDIAN_OF_NUMBER_OF_SESSIONS = 100;

    private final ConcurrentMap<String, CustomLinkedHashMap<Integer, IManageablePage>> cache = new ConcurrentHashMap<>(MEDIAN_OF_NUMBER_OF_SESSIONS);

    @Override
    public void destroy() {
        cache.clear();
    }

    @Override
    public IManageablePage getPage(final String sessionId, final int pageId) {
        LOGGER.info("getPage. SessionId: {}, pageId: {}", sessionId, pageId);
        final Map<Integer, IManageablePage> sessionCache = getSessionCache(sessionId);
        final RequestCycle requestCycle = RequestCycle.get();
        if (sessionCache == null) {
            LOGGER.warn("Missing cache. SessionId: {}, pageId: {}, URL: {}", sessionId, pageId, requestCycle == null ? "" : requestCycle.getRequest().getUrl());
            return null;
        }

        IManageablePage page;
        // noinspection SynchronizationOnLocalVariableOrMethodParameter
        synchronized (sessionCache) {
            page = sessionCache.get(pageId);
        }

        if (page == null && LOGGER.isDebugEnabled()) {
            LOGGER.debug("Missed page. SessionId: {}, pageId: {}, URL: {}", sessionId, pageId, requestCycle == null ? "" : requestCycle.getRequest().getUrl());
        }

        return page;
    }

    @Override
    public void removePage(final String sessionId, final int pageId) {
        if (LOGGER.isDebugEnabled()) {
            LOGGER.debug("removePage. SessionId: {}, pageId: {}", sessionId, pageId);
        }
        final Map<Integer, IManageablePage> sessionCache = getSessionCache(sessionId);
        if (sessionCache != null) {
            // noinspection SynchronizationOnLocalVariableOrMethodParameter
            synchronized (sessionCache) {
                sessionCache.remove(pageId);
            }
        }
    }

    @Override
    public void storePage(final String sessionId, final IManageablePage page) {
        if (LOGGER.isDebugEnabled()) {
            LOGGER.debug("storePage. SessionId: {}, pageId: {}, cache-size: {}", sessionId, page.getPageId(), cache.size());
        }
        final LinkedHashMap<Integer, IManageablePage> sessionCache = getOrCreateSessionCache(sessionId);
        final int pageId = page.getPageId();
        // noinspection SynchronizationOnLocalVariableOrMethodParameter
        synchronized (sessionCache) {
            if (sessionCache.containsKey(pageId)) {
                // do this to change insertion order and update least inserted entry
                sessionCache.remove(pageId);
                sessionCache.put(pageId, page);
            } else {
                sessionCache.put(pageId, page);
            }
        }
    }

    /**
     * @param sessionId
     */
    @Override
    public void unbind(final String sessionId) {
        if (LOGGER.isDebugEnabled()) {
            LOGGER.debug("unbind/cache-remove. SessionId: {}", sessionId);
        }
        cache.remove(sessionId);
    }

    @Override
    public Serializable prepareForSerialization(final String sessionId, final Serializable page) {
        return null;
    }

    @Override
    public Object restoreAfterSerialization(final Serializable serializable) {
        return null;
    }

    @Override
    public IManageablePage convertToPage(final Object page) {
        return (IManageablePage) page;
    }

    private Map<Integer, IManageablePage> getSessionCache(final String sessionId) {
        return cache.get(sessionId);
    }

    private CustomLinkedHashMap<Integer, IManageablePage> getOrCreateSessionCache(final String sessionId) {
        return cache.computeIfAbsent(sessionId, (final String s) -> new CustomLinkedHashMap<>());
    }

    /**
     * Mimics "least recently inserted" cache
     */
    private static class CustomLinkedHashMap<K, V> extends LinkedHashMap<K, V> {

        private static final long serialVersionUID = 1L;
        /**
         * use this parameter to control memory consumption and frequency of appearance of PageExpiredException
         */
        private static final int MAX_PAGES_PER_SESSION = 3;

        @Override
        protected boolean removeEldestEntry(final Map.Entry<K, V> eldest) {
            return size() > MAX_PAGES_PER_SESSION;
        }
    }
}

如何在Wicket 1.5中禁用序列化？

5 个答案: