common 包，基础组件

src/main/java/cn/iocoder/dashboard/util/collection/CollectionUtils.java

@@ -0,0 +1,66 @@
+package cn.iocoder.dashboard.util.collection;
+
+import cn.hutool.core.collection.CollectionUtil;
+
+import java.util.*;
+import java.util.function.Function;
+import java.util.stream.Collectors;
+
+/**
+ * Collection 工具类
+ *
+ * @author 芋道源码
+ */
+public class CollectionUtils {
+
+    public static <T> Set<T> asSet(T... objs) {
+        return new HashSet<>(Arrays.asList(objs));
+    }
+
+    public static <T, U> List<U> convertList(List<T> from, Function<T, U> func) {
+        return from.stream().map(func).collect(Collectors.toList());
+    }
+
+    public static <T, U> Set<U> convertSet(List<T> from, Function<T, U> func) {
+        return from.stream().map(func).collect(Collectors.toSet());
+    }
+
+    public static <T, K> Map<K, T> convertMap(List<T> from, Function<T, K> keyFunc) {
+        return from.stream().collect(Collectors.toMap(keyFunc, item -> item));
+    }
+
+    public static <T, K, V> Map<K, V> convertMap(List<T> from, Function<T, K> keyFunc, Function<T, V> valueFunc) {
+        return from.stream().collect(Collectors.toMap(keyFunc, valueFunc));
+    }
+
+    public static <T, K> Map<K, List<T>> convertMultiMap(List<T> from, Function<T, K> keyFunc) {
+        return from.stream().collect(Collectors.groupingBy(keyFunc,
+                Collectors.mapping(t -> t, Collectors.toList())));
+    }
+
+    public static <T, K, V> Map<K, List<V>> convertMultiMap(List<T> from, Function<T, K> keyFunc, Function<T, V> valueFunc) {
+        return from.stream().collect(Collectors.groupingBy(keyFunc,
+                Collectors.mapping(valueFunc, Collectors.toList())));
+    }
+
+    // 暂时没想好名字，先以 2 结尾噶
+    public static <T, K, V> Map<K, Set<V>> convertMultiMap2(List<T> from, Function<T, K> keyFunc, Function<T, V> valueFunc) {
+        return from.stream().collect(Collectors.groupingBy(keyFunc, Collectors.mapping(valueFunc, Collectors.toSet())));
+    }
+
+    public static boolean containsAny(Collection<?> source, Collection<?> candidates) {
+        return org.springframework.util.CollectionUtils.containsAny(source, candidates);
+    }
+
+    public static <T> T getFirst(List<T> from) {
+        return !CollectionUtil.isEmpty(from) ? from.get(0) : null;
+    }
+
+    public static <T> void addIfNotNull(Collection<T> coll, T item) {
+        if (item == null) {
+            return;
+        }
+        coll.add(item);
+    }
+
+}