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add method

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This commit is contained in:
Looly 2022-07-05 21:54:41 +08:00
parent fc6a0567b4
commit 34835939d2
3 changed files with 78 additions and 14 deletions
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1
CHANGELOG.md
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@ -11,6 +11,7 @@
* 【core 】 合成注解SyntheticAnnotation提取为接口，并为实现类添加注解选择器和属性处理器（pr#678@Gitee）
* 【core 】 增加BeanValueProvider（issue#I5FBHV@Gitee）
* 【core 】 Convert工具类中，新增中文大写数字金额转换为数字工具方法（pr#674@Gitee）
* 【core 】 新增CollectorUtil.reduceListMap()（pr#676@Gitee）
*
### 🐞Bug修复

61
hutool-core/src/main/java/cn/hutool/core/stream/CollectorUtil.java
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@ -3,12 +3,13 @@ package cn.hutool.core.stream;
import cn.hutool.core.lang.Opt;
import cn.hutool.core.util.StrUtil;
import java.util.ArrayList;
import java.util.Collections;
import java.util.EnumSet;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.List;
import java.util.StringJoiner;
import java.util.function.BiConsumer;
import java.util.function.BinaryOperator;
@ -99,26 +100,23 @@ public class CollectorUtil {
public static <T, K, D, A, M extends Map<K, D>> Collector<T, ?, M> groupingBy(Function<? super T, ? extends K> classifier,
Supplier<M> mapFactory,
Collector<? super T, A, D> downstream) {
Supplier<A> downstreamSupplier = downstream.supplier();
BiConsumer<A, ? super T> downstreamAccumulator = downstream.accumulator();
BiConsumer<Map<K, A>, T> accumulator = (m, t) -> {
K key = Opt.ofNullable(t).map(classifier).orElse(null);
A container = m.computeIfAbsent(key, k -> downstreamSupplier.get());
final Supplier<A> downstreamSupplier = downstream.supplier();
final BiConsumer<A, ? super T> downstreamAccumulator = downstream.accumulator();
final BiConsumer<Map<K, A>, T> accumulator = (m, t) -> {
final K key = Opt.ofNullable(t).map(classifier).orElse(null);
final A container = m.computeIfAbsent(key, k -> downstreamSupplier.get());
downstreamAccumulator.accept(container, t);
};
BinaryOperator<Map<K, A>> merger = mapMerger(downstream.combiner());
@SuppressWarnings("unchecked")
Supplier<Map<K, A>> mangledFactory = (Supplier<Map<K, A>>) mapFactory;
final BinaryOperator<Map<K, A>> merger = mapMerger(downstream.combiner());
@SuppressWarnings("unchecked") final Supplier<Map<K, A>> mangledFactory = (Supplier<Map<K, A>>) mapFactory;
if (downstream.characteristics().contains(Collector.Characteristics.IDENTITY_FINISH)) {
return new SimpleCollector<>(mangledFactory, accumulator, merger, CH_ID);
} else {
@SuppressWarnings("unchecked")
Function<A, A> downstreamFinisher = (Function<A, A>) downstream.finisher();
Function<Map<K, A>, M> finisher = intermediate -> {
@SuppressWarnings("unchecked") final Function<A, A> downstreamFinisher = (Function<A, A>) downstream.finisher();
final Function<Map<K, A>, M> finisher = intermediate -> {
intermediate.replaceAll((k, v) -> downstreamFinisher.apply(v));
@SuppressWarnings("unchecked")
M castResult = (M) intermediate;
@SuppressWarnings("unchecked") final M castResult = (M) intermediate;
return castResult;
};
return new SimpleCollector<>(mangledFactory, accumulator, merger, finisher, CH_NOID);
@ -214,5 +212,40 @@ public class CollectorUtil {
};
}
/**
* 聚合这种数据类型:{@code Collection<Map<K,V>> => Map<K,List<V>>}
* 其中key相同的value，会累加到List中
*
* @param <K> key的类型
* @param <V> value的类型
* @return 聚合后的map
* @since 5.8.5
*/
public static <K, V> Collector<Map<K, V>, ?, Map<K, List<V>>> reduceListMap() {
return reduceListMap(HashMap::new);
}
/**
* 聚合这种数据类型:{@code Collection<Map<K,V>> => Map<K,List<V>>}
* 其中key相同的value，会累加到List中
*
* @param mapSupplier 可自定义map的类型如concurrentHashMap等
* @param <K> key的类型
* @param <V> value的类型
* @param <R> 返回值的类型
* @return 聚合后的map
* @since 5.8.5
*/
public static <K, V, R extends Map<K, List<V>>> Collector<Map<K, V>, ?, R> reduceListMap(final Supplier<R> mapSupplier) {
return Collectors.reducing(mapSupplier.get(), value -> {
final R result = mapSupplier.get();
value.forEach((k, v) -> result.computeIfAbsent(k, i -> new ArrayList<>()).add(v));
return result;
}, (l, r) -> {
r.forEach((k, v) -> l.computeIfAbsent(k, i -> new ArrayList<>()).addAll(v));
return l;
}
);
}
}

30
hutool-core/src/test/java/cn/hutool/core/stream/CollectorUtilTest.java Normal file
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@ -0,0 +1,30 @@
package cn.hutool.core.stream;
import cn.hutool.core.map.MapUtil;
import org.junit.Assert;
import org.junit.Test;
import java.util.Arrays;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.stream.Collectors;
public class CollectorUtilTest {
@Test
public void reduceListMapTest() {
final Set<Map<String, Integer>> nameScoreMapList = StreamUtil.of(
// 集合内的第一个map，包含两个key value
MapUtil.builder("苏格拉底", 1).put("特拉叙马霍斯", 3).build(),
MapUtil.of("苏格拉底", 2),
MapUtil.of("特拉叙马霍斯", 1),
MapUtil.of("特拉叙马霍斯", 2)
).collect(Collectors.toSet());
// 执行聚合
final Map<String, List<Integer>> nameScoresMap = nameScoreMapList.stream().collect(CollectorUtil.reduceListMap());
Assert.assertEquals(MapUtil.builder("苏格拉底", Arrays.asList(1, 2))
.put("特拉叙马霍斯", Arrays.asList(3, 1, 2)).build(),
nameScoresMap);
}
}