优化 IndexedComparator性能,底层实现由array变为hashMap,避免循环equals

hutool-core/src/main/java/cn/hutool/core/comparator/IndexedComparator.java

@@ -1,9 +1,10 @@
 package cn.hutool.core.comparator;
 
 import cn.hutool.core.lang.Assert;
-import cn.hutool.core.util.ArrayUtil;
 
 import java.util.Comparator;
+import java.util.HashMap;
+import java.util.Map;
 
 /**
  * 按照数组的顺序正序排列，数组的元素位置决定了对象的排序先后<br>
@@ -16,7 +17,10 @@ import java.util.Comparator;
 public class IndexedComparator<T> implements Comparator<T> {
 
 	private final boolean atEndIfMiss;
-	private final T[] array;
+	/**
+	 * map存储对象类型所在列表的位置,k为对象，v为位置
+	 */
+	private final Map<? super T, Integer> map;
 
 	/**
 	 * 构造
@@ -28,6 +32,19 @@ public class IndexedComparator<T> implements Comparator<T> {
 		this(false, objs);
 	}
 
+
+	/**
+	 * 构造
+	 *
+	 * @param atEndIfMiss 如果不在列表中是否排在后边
+	 * @param map         参与排序的map，map中的value值大小决定了对象的排序先后
+	 */
+	@SuppressWarnings("unchecked")
+	private IndexedComparator(boolean atEndIfMiss, Map<? super T, Integer> map) {
+		this.atEndIfMiss = atEndIfMiss;
+		this.map = map;
+	}
+
 	/**
 	 * 构造
 	 *
@@ -38,7 +55,10 @@ public class IndexedComparator<T> implements Comparator<T> {
 	public IndexedComparator(boolean atEndIfMiss, T... objs) {
 		Assert.notNull(objs, "'objs' array must not be null");
 		this.atEndIfMiss = atEndIfMiss;
-		this.array = objs;
+		map = new HashMap<>(1 + (int) (objs.length / 0.75));
+		for (int i = 0; i < objs.length; i++) {
+			map.put(objs[i], i);
+		}
 	}
 
 	@Override
@@ -47,8 +67,8 @@ public class IndexedComparator<T> implements Comparator<T> {
 		final int index2 = getOrder(o2);
 
 		if (index1 == index2) {
-			if (index1 < 0 || index1 == this.array.length) {
-				// 任意一个元素不在列表中, 返回原顺序
+			if (index1 < 0 || index1 == this.map.size()) {
+				// 任意一个元素不在map中, 返回原顺序
 				return 1;
 			}
 
@@ -60,15 +80,15 @@ public class IndexedComparator<T> implements Comparator<T> {
 	}
 
 	/**
-	 * 查找对象类型所在列表的位置
+	 * 查找对象类型所对应的顺序值,即在原列表中的顺序
 	 *
 	 * @param object 对象
-	 * @return 位置，未找到位置根据{@link #atEndIfMiss}取不同值，false返回-1，否则返回列表长度
+	 * @return 位置，未找到位置根据{@link #atEndIfMiss}取不同值，false返回-1，否则返回map长度
 	 */
 	private int getOrder(T object) {
-		int order = ArrayUtil.indexOf(array, object);
-		if (order < 0) {
-			order = this.atEndIfMiss ? this.array.length : -1;
+		Integer order = map.get(object);
+		if (order == null) {
+			order = this.atEndIfMiss ? this.map.size() : -1;
 		}
 		return order;
 	}

hutool-core/src/test/java/cn/hutool/core/comparator/IndexedComparatorTest.java

@@ -0,0 +1,47 @@
+package cn.hutool.core.comparator;
+
+import cn.hutool.core.collection.CollectionUtil;
+import lombok.AllArgsConstructor;
+import lombok.Data;
+import org.junit.Assert;
+import org.junit.Test;
+
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.HashSet;
+import java.util.List;
+
+public class IndexedComparatorTest {
+	@Test
+	public void sortTest() {
+		final Object[] arr ={"a", "b", new User("9", null), "1",3,null,"2"};
+		final Collection<Object> set = new HashSet<>(Arrays.asList(arr));
+
+		final List<Object> sortSet = CollectionUtil.sort(set, new IndexedComparator<>(arr));
+
+		Assert.assertEquals("a", sortSet.get(0));
+		Assert.assertEquals( new User("9", null), sortSet.get(2));
+		Assert.assertEquals(3, sortSet.get(4));
+		Assert.assertNull(sortSet.get(5));
+	}
+
+	@Test
+	public void reversedTest() {
+		final Object[] arr ={"a", "b", new User("9", null), "1",3,null,"2"};
+		final Collection<Object> set = new HashSet<>(Arrays.asList(arr));
+
+		final List<Object> sortSet = CollectionUtil.sort(set, new IndexedComparator<>(arr).reversed());
+
+		Assert.assertEquals("a", sortSet.get(6));
+		Assert.assertNull(sortSet.get(1));
+		Assert.assertEquals( new User("9", null), sortSet.get(4));
+		Assert.assertEquals(3, sortSet.get(2));
+	}
+
+	@Data
+	@AllArgsConstructor
+	static class User{
+		private String a;
+		private String b;
+	}
+}