add class

hutool-core/src/main/java/cn/hutool/core/collection/ConcurrentHashSet.java

@@ -1,8 +1,6 @@
 package cn.hutool.core.collection;
 
-import java.util.AbstractSet;
 import java.util.Collection;
-import java.util.Iterator;
 import java.util.concurrent.ConcurrentHashMap;
 
 /**
@@ -13,20 +11,16 @@ import java.util.concurrent.ConcurrentHashMap;
  * @param <E> 元素类型
  * @since 3.1.0
  */
-public class ConcurrentHashSet<E> extends AbstractSet<E> implements java.io.Serializable {
+public class ConcurrentHashSet<E> extends SetFromMap<E> {
 	private static final long serialVersionUID = 7997886765361607470L;
 
-	/** 持有对象。如果值为此对象表示有数据，否则无数据 */
-	private static final Boolean PRESENT = true;
-	private final ConcurrentHashMap<E, Boolean> map;
-
 	// ----------------------------------------------------------------------------------- Constructor start
 	/**
 	 * 构造<br>
 	 * 触发因子为默认的0.75
 	 */
 	public ConcurrentHashSet() {
-		map = new ConcurrentHashMap<>();
+		super(new ConcurrentHashMap<>());
 	}
 
 	/**
@@ -36,7 +30,7 @@ public class ConcurrentHashSet<E> extends AbstractSet<E> implements java.io.Seri
 	 * @param initialCapacity 初始大小
 	 */
 	public ConcurrentHashSet(final int initialCapacity) {
-		map = new ConcurrentHashMap<>(initialCapacity);
+		super(new ConcurrentHashMap<>(initialCapacity));
 	}
 
 	/**
@@ -46,7 +40,7 @@ public class ConcurrentHashSet<E> extends AbstractSet<E> implements java.io.Seri
 	 * @param loadFactor 加载因子。此参数决定数据增长时触发的百分比
 	 */
 	public ConcurrentHashSet(final int initialCapacity, final float loadFactor) {
-		map = new ConcurrentHashMap<>(initialCapacity, loadFactor);
+		super(new ConcurrentHashMap<>(initialCapacity, loadFactor));
 	}
 
 	/**
@@ -57,7 +51,7 @@ public class ConcurrentHashSet<E> extends AbstractSet<E> implements java.io.Seri
 	 * @param concurrencyLevel 线程并发度
 	 */
 	public ConcurrentHashSet(final int initialCapacity, final float loadFactor, final int concurrencyLevel) {
-		map = new ConcurrentHashMap<>(initialCapacity, loadFactor, concurrencyLevel);
+		super(new ConcurrentHashMap<>(initialCapacity, loadFactor, concurrencyLevel));
 	}
 
 	/**
@@ -65,52 +59,14 @@ public class ConcurrentHashSet<E> extends AbstractSet<E> implements java.io.Seri
 	 * @param iter {@link Iterable}
 	 */
 	public ConcurrentHashSet(final Iterable<E> iter) {
+		super(iter instanceof  Collection ? new ConcurrentHashMap<>((int)(((Collection<E>)iter).size() / 0.75f)) : new ConcurrentHashMap<>());
 		if(iter instanceof Collection) {
-			final Collection<E> collection = (Collection<E>)iter;
-			map = new ConcurrentHashMap<>((int)(collection.size() / 0.75f));
-			this.addAll(collection);
+			this.addAll((Collection<E>)iter);
 		}else {
-			map = new ConcurrentHashMap<>();
 			for (final E e : iter) {
 				this.add(e);
 			}
 		}
 	}
 	// ----------------------------------------------------------------------------------- Constructor end
-
-	@Override
-	public Iterator<E> iterator() {
-		return map.keySet().iterator();
-	}
-
-	@Override
-	public int size() {
-		return map.size();
-	}
-
-	@Override
-	public boolean isEmpty() {
-		return map.isEmpty();
-	}
-
-	@Override
-	public boolean contains(final Object o) {
-		//noinspection SuspiciousMethodCalls
-		return map.containsKey(o);
-	}
-
-	@Override
-	public boolean add(final E e) {
-		return map.put(e, PRESENT) == null;
-	}
-
-	@Override
-	public boolean remove(final Object o) {
-		return PRESENT.equals(map.remove(o));
-	}
-
-	@Override
-	public void clear() {
-		map.clear();
-	}
 }

hutool-core/src/main/java/cn/hutool/core/collection/SetFromMap.java

@@ -0,0 +1,139 @@
+package cn.hutool.core.collection;
+
+import java.io.IOException;
+import java.io.Serializable;
+import java.util.AbstractSet;
+import java.util.Collection;
+import java.util.Iterator;
+import java.util.Map;
+import java.util.Set;
+import java.util.Spliterator;
+import java.util.function.Consumer;
+import java.util.function.Predicate;
+import java.util.stream.Stream;
+
+/**
+ * 基于Map的Set实现
+ *
+ * @param <E> 元素类型
+ * @author guava
+ */
+public class SetFromMap<E> extends AbstractSet<E> implements Serializable {
+	private static final long serialVersionUID = 1L;
+
+	private final Map<E, Boolean> m;  // The backing map
+	private transient Set<E> s;       // Its keySet
+
+	public SetFromMap(final Map<E, Boolean> map) {
+		m = map;
+		s = map.keySet();
+	}
+
+	@Override
+	public void clear() {
+		m.clear();
+	}
+
+	@Override
+	public int size() {
+		return m.size();
+	}
+
+	@Override
+	public boolean isEmpty() {
+		return m.isEmpty();
+	}
+
+	@SuppressWarnings("SuspiciousMethodCalls")
+	@Override
+	public boolean contains(final Object o) {
+		return m.containsKey(o);
+	}
+
+	@Override
+	public boolean remove(final Object o) {
+		return m.remove(o) != null;
+	}
+
+	@Override
+	public boolean add(final E e) {
+		return m.put(e, Boolean.TRUE) == null;
+	}
+
+	@Override
+	public Iterator<E> iterator() {
+		return s.iterator();
+	}
+
+	@Override
+	public Object[] toArray() {
+		return s.toArray();
+	}
+
+	@SuppressWarnings("SuspiciousToArrayCall")
+	@Override
+	public <T> T[] toArray(final T[] a) {
+		return super.toArray(a);
+	}
+
+	@Override
+	public String toString() {
+		return s.toString();
+	}
+
+	@Override
+	public int hashCode() {
+		return s.hashCode();
+	}
+
+	@SuppressWarnings("EqualsWhichDoesntCheckParameterClass")
+	@Override
+	public boolean equals(final Object o) {
+		return o == this || s.equals(o);
+	}
+
+	@Override
+	public boolean containsAll(final Collection<?> c) {
+		return s.containsAll(c);
+	}
+
+	@Override
+	public boolean removeAll(final Collection<?> c) {
+		return s.removeAll(c);
+	}
+
+	@Override
+	public boolean retainAll(final Collection<?> c) {
+		return s.retainAll(c);
+	}
+
+	@Override
+	public void forEach(final Consumer<? super E> action) {
+		s.forEach(action);
+	}
+
+	@Override
+	public boolean removeIf(final Predicate<? super E> filter) {
+		return s.removeIf(filter);
+	}
+
+	@Override
+	public Spliterator<E> spliterator() {
+		return s.spliterator();
+	}
+
+	@Override
+	public Stream<E> stream() {
+		return s.stream();
+	}
+
+	@Override
+	public Stream<E> parallelStream() {
+		return s.parallelStream();
+	}
+
+	private void readObject(final java.io.ObjectInputStream stream) throws IOException, ClassNotFoundException {
+		stream.defaultReadObject();
+		s = m.keySet();
+	}
+}

hutool-core/src/main/java/cn/hutool/core/collection/SetUtil.java

@@ -8,6 +8,7 @@ import java.util.Enumeration;
 import java.util.HashSet;
 import java.util.Iterator;
 import java.util.LinkedHashSet;
+import java.util.Map;
 import java.util.Set;
 
 /**
@@ -125,6 +126,17 @@ public class SetUtil {
 		return set;
 	}
 
+	/**
+	 * 新建一个SetFromMap
+	 *
+	 * @param <T> 集合元素类型
+	 * @param map Map
+	 * @return SetFromMap对象
+	 */
+	public static <T> SetFromMap<T> of(final Map<T, Boolean> map) {
+		return new SetFromMap<>(map);
+	}
+
 	/**
 	 * 数组转为一个不可变List<br>
 	 * 类似于Java9中的List.of