Java SoftReference類代碼示例

import java.lang.ref.SoftReference; //導入依賴的package包/類
/**
 * Returns an immutable set of system time zone IDs.
 * Etc/Unknown is excluded.
 * @return An immutable set of system time zone IDs.
 */
private static synchronized Set<String> getSystemZIDs() {
    Set<String> systemZones = null;
    if (REF_SYSTEM_ZONES != null) {
        systemZones = REF_SYSTEM_ZONES.get();
    }
    if (systemZones == null) {
        Set<String> systemIDs = new TreeSet<String>();
        String[] allIDs = getZoneIDs();
        for (String id : allIDs) {
            // exclude Etc/Unknown
            if (id.equals(TimeZone.UNKNOWN_ZONE_ID)) {
                continue;
            }
            systemIDs.add(id);
        }
        systemZones = Collections.unmodifiableSet(systemIDs);
        REF_SYSTEM_ZONES = new SoftReference<Set<String>>(systemZones);
    }
    return systemZones;
}
 

import java.lang.ref.SoftReference; //導入依賴的package包/類
public TlSbTlNbwFCImmerseMode(@NonNull Activity activity) {
    mActivityRef = new SoftReference<>(activity);

    Window window = activity.getWindow();
    WindowUtils.addWindowFlags(window, FLAG_TRANSLUCENT_STATUS);
    WindowUtils.addWindowFlags(window, FLAG_TRANSLUCENT_NAVIGATION);

    mActivityConfig = new ActivityConfig(activity);
    mCompatStatusBarView = setupStatusBarView(activity);
    mCompatNavigationBarView = setupNavigationBarView(activity);

    mCompatStatusBarView.setBackgroundColor(Color.TRANSPARENT);
    if (mCompatNavigationBarView != null) {
        mCompatNavigationBarView.setBackgroundColor(Color.TRANSPARENT);
    }
}
 

import java.lang.ref.SoftReference; //導入依賴的package包/類
private SDE sourceDebugExtensionInfo() {
    if (!vm.canGetSourceDebugExtension()) {
        return NO_SDE_INFO_MARK;
    }
    SDE sde = (sdeRef == null) ?  null : sdeRef.get();
    if (sde == null) {
        String extension = null;
        try {
            extension = JDWP.ReferenceType.SourceDebugExtension.
                process(vm, this).extension;
        } catch (JDWPException exc) {
            if (exc.errorCode() != JDWP.Error.ABSENT_INFORMATION) {
                sdeRef = new SoftReference<SDE>(NO_SDE_INFO_MARK);
                throw exc.toJDIException();
            }
        }
        if (extension == null) {
            sde = NO_SDE_INFO_MARK;
        } else {
            sde = new SDE(extension);
        }
        sdeRef = new SoftReference<SDE>(sde);
    }
    return sde;
}
 

import java.lang.ref.SoftReference; //導入依賴的package包/類
/**
 * Check the history for a map that already has the given property added.
 *
 * @param property {@link Property} to add.
 *
 * @return Existing map or {@code null} if not found.
 */
private PropertyMap checkHistory(final Property property) {

    if (history != null) {
        final SoftReference<PropertyMap> ref = history.get(property);
        final PropertyMap historicMap = ref == null ? null : ref.get();

        if (historicMap != null) {
            if (Context.DEBUG) {
                historyHit++;
            }

            return historicMap;
        }
    }

    return null;
}
 

import java.lang.ref.SoftReference; //導入依賴的package包/類
static Map<String, String> getCachedAliasTable() {
    Map<String, String> aliases = null;

    SoftReference<Map<String, String>> cache = aliasTable;
    if (cache != null) {
        aliases = cache.get();
    }
    return aliases;
}
 

import java.lang.ref.SoftReference; //導入依賴的package包/類
public synchronized Enumeration<?> getFinalizerObjects() {
    Vector<?> obj;
    if (finalizablesCache != null &&
        (obj = finalizablesCache.get()) != null) {
        return obj.elements();
    }

    JavaClass clazz = findClass("java.lang.ref.Finalizer");
    JavaObject queue = (JavaObject) clazz.getStaticField("queue");
    JavaThing tmp = queue.getField("head");
    Vector<JavaHeapObject> finalizables = new Vector<JavaHeapObject>();
    if (tmp != getNullThing()) {
        JavaObject head = (JavaObject) tmp;
        while (true) {
            JavaHeapObject referent = (JavaHeapObject) head.getField("referent");
            JavaThing next = head.getField("next");
            if (next == getNullThing() || next.equals(head)) {
                break;
            }
            head = (JavaObject) next;
            finalizables.add(referent);
        }
    }
    finalizablesCache = new SoftReference<Vector<?>>(finalizables);
    return finalizables.elements();
}
 

import java.lang.ref.SoftReference; //導入依賴的package包/類
/**
 * This implementation simply reads and parses `java.class.path' property and creates a ClassPath
 * out of it.
 * @return  ClassPath that represents contents of system property java.class.path.
 */
@Override
public ClassPath getStandardLibraries() {
    synchronized (this) {
        ClassPath cp = (standardLibs == null ? null : standardLibs.get());
        if (cp != null)
            return cp;
        final String pathSpec = getSystemProperties().get(SYSPROP_JAVA_CLASS_PATH);
        if (pathSpec == null) {
            cp = ClassPathSupport.createClassPath(new URL[0]);
        }
        else {
            cp = Util.createClassPath (pathSpec);
        }
        standardLibs = new SoftReference<>(cp);
        return cp;
    }
}
 

import java.lang.ref.SoftReference; //導入依賴的package包/類
private synchronized static AntInstance getAntInstance() {
    AntInstance ai;
    if (antInstance != null) {
        ai = antInstance.get();
    } else {
        ai = null;
    }
    if (ai == null) {
        ai = createAntInstance();
        // XXX would be more accurate to stuff this struct into by BridgeImpl
        // so that it all lives or dies iff that class loader is still alive
        // (current impl is just workaround for JDK #6389107)
        antInstance = new SoftReference<AntInstance>(ai);
    }
    return ai;
}
 

import java.lang.ref.SoftReference; //導入依賴的package包/類
/**
 * Check prototype history for an existing property map with specified prototype.
 *
 * @param proto New prototype object.
 *
 * @return Existing {@link PropertyMap} or {@code null} if not found.
 */
private PropertyMap checkProtoHistory(final ScriptObject proto) {
    final PropertyMap cachedMap;
    if (protoHistory != null) {
        final SoftReference<PropertyMap> weakMap = protoHistory.get(proto);
        cachedMap = (weakMap != null ? weakMap.get() : null);
    } else {
        cachedMap = null;
    }

    if (Context.DEBUG && cachedMap != null) {
        protoHistoryHit++;
    }

    return cachedMap;
}
 

import java.lang.ref.SoftReference; //導入依賴的package包/類
private static synchronized Image getIconForDefault(Class klass) {
    Map<String,Object> icons;
    if ((imageCache == null) || ((icons = imageCache.get()) == null)) {
        icons = createImageCache();
        imageCache = new SoftReference<Map<String,Object>>(icons);
    }
    
    String name = klass.getName();
    Object img = icons.get(name);
    
    if (img == null) {
        return null;
    }
    
    if (img instanceof Image) {
        return (Image) img;
    } else {
        Image image = java.awt.Toolkit.getDefaultToolkit().createImage(
                             BeanSupport.class.getResource((String)img));
        icons.put(name, image);
        return image;
    }
}
 

import java.lang.ref.SoftReference; //導入依賴的package包/類
private CacheBlock(CharSequence code, TokenSequence<HTMLTokenId> tokenSequence, int firstElementIndex, int firstTokenIndex) {
    this.code = code;
    this.tokenSequence = tokenSequence;

    this.startIndex = firstElementIndex;
    this.firstTokenIndex = firstTokenIndex;

    CacheBlockContent block = new CacheBlockContent(code, tokenSequence, firstTokenIndex);
    int blockSize = block.getElements().size();
    this.endIndex = firstElementIndex + blockSize;
    
    this.startOffset = blockSize == 0 ? -1 : block.getFirstElement().from();
    
    this.endOffset = blockSize == 0 ? -1 : block.getLastElement().to();
    this.lastTokenIndex = block.getLastTokenIndex();
    
    blockReads++;

    blockReference = new SoftReference<>(block);
}
 

import java.lang.ref.SoftReference; //導入依賴的package包/類
public SerializeWriter(Writer writer, SerializerFeature... features){
    this.writer = writer;

    SoftReference<char[]> ref = bufLocal.get();

    if (ref != null) {
        buf = ref.get();
        bufLocal.set(null);
    }

    if (buf == null) {
        buf = new char[1024];
    }

    int featuresValue = 0;
    for (SerializerFeature feature : features) {
        featuresValue |= feature.getMask();
    }
    this.features = featuresValue;
}
 

import java.lang.ref.SoftReference; //導入依賴的package包/類
/**
 * Verify that the given AccessControlContext has permission to
 * accept this connection.
 */
void checkAcceptPermission(SecurityManager sm,
                           AccessControlContext acc)
{
    /*
     * Note: no need to synchronize on cache-related fields, since this
     * method only gets called from the ConnectionHandler's thread.
     */
    if (sm != cacheSecurityManager) {
        okContext = null;
        authCache = new WeakHashMap<AccessControlContext,
                                    Reference<AccessControlContext>>();
        cacheSecurityManager = sm;
    }
    if (acc.equals(okContext) || authCache.containsKey(acc)) {
        return;
    }
    InetAddress addr = socket.getInetAddress();
    String host = (addr != null) ? addr.getHostAddress() : "*";

    sm.checkAccept(host, socket.getPort());

    authCache.put(acc, new SoftReference<AccessControlContext>(acc));
    okContext = acc;
}
 

import java.lang.ref.SoftReference; //導入依賴的package包/類
/**
 * Get the scannables, ordered by level, lowest first
 * @param position
 * @return
 * @throws ScanningException
 */
protected Map<Integer, List<L>> getLevelOrderedDevices() throws ScanningException {
	if (sortedObjects!=null && sortedObjects.get()!=null) return sortedObjects.get();

	final Collection<L> devices = getDevices();

	if (devices == null) return Collections.emptyMap();

	final Map<Integer, List<L>> devicesByLevel = new TreeMap<>();
	for (L object : devices) {
		final int level = object.getLevel();

		if (!devicesByLevel.containsKey(level)) devicesByLevel.put(level, new ArrayList<L>(7));
		devicesByLevel.get(level).add(object);
	}
	if (isLevelCachingAllowed()) sortedObjects = new SoftReference<Map>(devicesByLevel);

	return devicesByLevel;
}
 

import java.lang.ref.SoftReference; //導入依賴的package包/類
/**
 * Accessor to get thread-local recycler instance
 */
public static BufferRecycler instance()
{
    SoftReference<BufferRecycler> ref = recyclerRef.get();

    BufferRecycler bufferRecycler;
    if (ref == null) {
        bufferRecycler = null;
    }
    else {
        bufferRecycler = ref.get();
    }

    if (bufferRecycler == null) {
        bufferRecycler = new BufferRecycler();
        recyclerRef.set(new SoftReference<BufferRecycler>(bufferRecycler));
    }
    return bufferRecycler;
}