添加针对 bigDecimal类型的avg方法

hutool-core/src/main/java/cn/hutool/core/stream/EasyStream.java

@@ -1,13 +1,19 @@
 package cn.hutool.core.stream;
 
+import cn.hutool.core.collection.CollUtil;
 import cn.hutool.core.lang.Opt;
+import cn.hutool.core.math.NumberUtil;
 import cn.hutool.core.util.ArrayUtil;
 import cn.hutool.core.util.ObjUtil;
 
+import java.math.BigDecimal;
+import java.math.RoundingMode;
+import java.util.List;
 import java.util.Objects;
 import java.util.OptionalDouble;
 import java.util.Spliterator;
 import java.util.function.*;
+import java.util.stream.Collectors;
 import java.util.stream.Stream;
 import java.util.stream.StreamSupport;
 
@@ -299,6 +305,34 @@ public class EasyStream<T> extends AbstractEnhancedWrappedStream<T, EasyStream<T
 		return stream.mapToDouble(mapper).sum();
 	}
 
+	/**
+	 * 计算decimal的总和
+	 *
+	 * @param mapper 映射
+	 * @return {@link OptionalDouble}
+	 */
+	public BigDecimal sum(final Function<? super T, BigDecimal> mapper) {
+		return	stream.map(mapper).reduce(BigDecimal.ZERO, BigDecimal::add);
+	}
+
+	/**
+	 * 计算bigDecimal平均值
+	 * @param mapper 映射
+	 * @param scale 精度
+	 * @param roundingMode 舍入模式
+	 * @return 如果元素的长度为0 那么会返回为空的opt
+	 */
+	public Opt<BigDecimal> avg(final Function<? super T,BigDecimal> mapper,int scale,RoundingMode roundingMode){
+		//元素列表
+		List<BigDecimal> bigDecimalList = stream.map(mapper).collect(Collectors.toList());
+		if (CollUtil.isEmpty(bigDecimalList)){
+			return Opt.ofNullable(null);
+		}
+
+		return Opt.of(EasyStream.of(bigDecimalList).reduce(BigDecimal.ZERO, BigDecimal::add).divide(NumberUtil.toBigDecimal(bigDecimalList.size()),scale, roundingMode));
+	}
+
+
 
 
 	/**
@@ -333,6 +367,7 @@ public class EasyStream<T> extends AbstractEnhancedWrappedStream<T, EasyStream<T
 	}
 
 
+
 	/**
 	 * 建造者
 	 *

hutool-core/src/test/java/cn/hutool/core/stream/EasyStreamTest.java

@@ -1,12 +1,16 @@
 package cn.hutool.core.stream;
 
+import cn.hutool.core.collection.CollUtil;
 import cn.hutool.core.collection.ListUtil;
 import cn.hutool.core.map.MapUtil;
+import cn.hutool.core.math.NumberUtil;
 import org.junit.Assert;
 import org.junit.Test;
 
+import java.math.BigDecimal;
 import java.util.*;
 import java.util.concurrent.atomic.AtomicInteger;
+import java.util.function.Function;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
 
@@ -435,11 +439,46 @@ public class EasyStreamTest {
 
 
 	@Test
-	public void testIntSum() {
+	public void testIntSumAndAvg() {
 		int sum = EasyStream.of(1, 2, 3, 4, 5, 6, 7, 8, 9, 10).sum(Integer::intValue);
 		Assert.assertEquals(sum, 55);
-		double doubleSum = EasyStream.of(1.1, 2.2, 3.3, 4.4, 5.5, 6.6, 7.7, 8.8, 9.9, 10.10).sum(Double::doubleValue);
+
-		Assert.assertEquals(doubleSum,59.6);
+		//测试为空
+		List<Integer> integerList = new ArrayList<>();
+		int emptySum = EasyStream.of(integerList).sum(Integer::intValue);
+		Assert.assertEquals(emptySum, 0);
 	}
 
+	@Test
+	public void testDoubleSumAndAvg() {
+		double doubleSum = EasyStream.of(1.1, 2.2, 3.3, 4.4, 5.5, 6.6, 7.7, 8.8, 9.9, 10.10).sum(Double::doubleValue);
+		Assert.assertEquals(doubleSum, 59.6,2);
+
+		List<Double> doubleList = new ArrayList<>();
+		double emptySum = EasyStream.of(doubleList).sum(Double::doubleValue);
+		Assert.assertEquals(emptySum, 0.0,2);
+
+	}
+
+	@Test
+	public void testLongSumAndAvg() {
+		long sum = EasyStream.of(1L, 2L, 3L, 4L, 5L, 6L, 7L, 8L, 9L, 10L).sum(Long::longValue);
+		Assert.assertEquals(sum, 55);
+
+		List<Long> longList = new ArrayList<>();
+		double emptySum = EasyStream.of(longList).sum(Long::longValue);
+		Assert.assertEquals(emptySum, 0L);
+
+	}
+
+	@Test
+	public void testBigDecimalSumAndAvg() {
+		BigDecimal sum = EasyStream.of(NumberUtil.toBigDecimal(1.1), NumberUtil.toBigDecimal(2.2), NumberUtil.toBigDecimal(3.3), NumberUtil.toBigDecimal(4.4), NumberUtil.toBigDecimal(5.5), NumberUtil.toBigDecimal(6.6), NumberUtil.toBigDecimal(7.7), NumberUtil.toBigDecimal(8.8), NumberUtil.toBigDecimal(9.9), NumberUtil.toBigDecimal(10.10)).sum(Function.identity());
+		Assert.assertEquals(sum, 59.6);
+
+		List<BigDecimal> bigDecimalList = new ArrayList<>();
+		BigDecimal emptySum = EasyStream.of(bigDecimalList).sum(Function.identity());
+		Assert.assertEquals(emptySum, BigDecimal.ZERO);
+
+	}
 }