From de0a732616e59210c972dadf4aee26880aca3f94 Mon Sep 17 00:00:00 2001
From: ZhouXY108 <luquanlion@outlook.com>
Date: Fri, 11 Oct 2024 17:11:56 +0800
Subject: [PATCH] =?UTF-8?q?=E6=96=B0=E5=A2=9E=20BigDecimals#toPlainString?=
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---
 .../plusone/commons/util/BigDecimals.java     | 48 +++++++++++++++++++
 .../commons/util/BigDecimalsTests.java        | 17 +++++++
 2 files changed, 65 insertions(+)
 create mode 100644 src/test/java/xyz/zhouxy/plusone/commons/util/BigDecimalsTests.java

diff --git a/src/main/java/xyz/zhouxy/plusone/commons/util/BigDecimals.java b/src/main/java/xyz/zhouxy/plusone/commons/util/BigDecimals.java
index e502a77..cce0335 100644
--- a/src/main/java/xyz/zhouxy/plusone/commons/util/BigDecimals.java
+++ b/src/main/java/xyz/zhouxy/plusone/commons/util/BigDecimals.java
@@ -3,6 +3,7 @@ package xyz.zhouxy.plusone.commons.util;
 import java.math.BigDecimal;
 import java.math.RoundingMode;
 
+import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
 
 import com.google.common.base.Preconditions;
@@ -39,6 +40,53 @@ public class BigDecimals {
         return (StringTools.isNotBlank(val)) ? new BigDecimal(val) : ZERO;
     }
 
+    /**
+     * 默认除法运算精度
+     */
+    private static final int DEFAULT_STR_SCALE = 2;
+
+    private static final RoundingMode DEFAULT_STR_ROUNDING_MODE = RoundingMode.HALF_UP;
+
+    /**
+     * 使用四舍五入（{@link RoundingMode#HALF_UP}），保留两位小数，转为字符串。
+     */
+    public static String toPlainString(@Nonnull BigDecimal value) {
+        AssertTools.checkParameterNotNull("value", value);
+        return toPlainStringInternal(value, DEFAULT_STR_SCALE, DEFAULT_STR_ROUNDING_MODE);
+    }
+
+    /**
+     * 使用四舍五入（{@link RoundingMode#HALF_UP}），保留指定位的小数，转为字符串。
+     */
+    public static String toPlainString(@Nonnull BigDecimal value, int scale) {
+        AssertTools.checkParameterNotNull("value", value);
+        return toPlainStringInternal(value, scale, DEFAULT_STR_ROUNDING_MODE);
+    }
+
+    /**
+     * 使用指定 {@link RoundingMode}，保留两位小数，转为字符串。
+     */
+    public static String toPlainString(@Nonnull BigDecimal value, @Nonnull RoundingMode roundingMode) {
+        AssertTools.checkParameterNotNull("value", value);
+        AssertTools.checkParameterNotNull("rounding mode", roundingMode);
+        return toPlainStringInternal(value, DEFAULT_STR_SCALE, roundingMode);
+    }
+
+    /**
+     * 使用指定 {@link RoundingMode}，保留指定位的小数，转为字符串。
+     */
+    public static String toPlainString(@Nonnull BigDecimal value,
+            int scale, @Nonnull RoundingMode roundingMode) {
+        AssertTools.checkParameterNotNull("value", value);
+        AssertTools.checkParameterNotNull("rounding mode", roundingMode);
+        return toPlainStringInternal(value, scale, roundingMode);
+    }
+
+    private static String toPlainStringInternal(@Nonnull BigDecimal value,
+            int scale, @Nonnull RoundingMode roundingMode) {
+        return value.setScale(scale, roundingMode).toPlainString();
+    }
+
     /**
      * 默认除法运算精度
      */
diff --git a/src/test/java/xyz/zhouxy/plusone/commons/util/BigDecimalsTests.java b/src/test/java/xyz/zhouxy/plusone/commons/util/BigDecimalsTests.java
new file mode 100644
index 0000000..15a51e9
--- /dev/null
+++ b/src/test/java/xyz/zhouxy/plusone/commons/util/BigDecimalsTests.java
@@ -0,0 +1,17 @@
+package xyz.zhouxy.plusone.commons.util;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import org.junit.jupiter.api.Test;
+
+public class BigDecimalsTests {
+
+    @Test
+    void testToPlainString() {
+        assertEquals("8.09", BigDecimals.toPlainString(BigDecimals.of("8.090")));
+        assertEquals("8.09", BigDecimals.toPlainString(BigDecimals.of("8.094")));
+        assertEquals("8.10", BigDecimals.toPlainString(BigDecimals.of("8.095")));
+        assertEquals("8.10", BigDecimals.toPlainString(BigDecimals.of("8.096")));
+        assertEquals("8.10", BigDecimals.toPlainString(BigDecimals.of("8.100")));
+    }
+}