删除多余方法，修改方法名。

src/test/java/xyz/zhouxy/plusone/commons/util/BigDecimalsTests.java

@@ -18,16 +18,87 @@ package xyz.zhouxy.plusone.commons.util;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
 
+import java.math.BigDecimal;
+import java.math.RoundingMode;
+import java.util.function.Function;
+
 import org.junit.jupiter.api.Test;
 
+import lombok.extern.slf4j.Slf4j;
+
+@Slf4j
 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")));
+
+        BigDecimalFormatter formatter = BigDecimalFormatter.builder()
+                .setScale(2, RoundingMode.HALF_UP)
+                .stripTrailingZeros()
+                .build();
+
+        assertEquals("8.09", formatter.toPlainString(BigDecimals.of("8.090")));
+        assertEquals("8.09", formatter.toPlainString(BigDecimals.of("8.094")));
+        assertEquals("8.1", formatter.toPlainString(BigDecimals.of("8.095")));
+        assertEquals("8.1", formatter.toPlainString(BigDecimals.of("8.096")));
+        assertEquals("8.1", formatter.toPlainString(BigDecimals.of("8.100")));
+    }
+
+    @Test
+    void test() {
+        Object a = 100 % 3.0;
+        log.info("a: {}", a);
+    }
+}
+
+class BigDecimalFormatter {
+    private final Function<BigDecimal, BigDecimal> func;
+
+    private BigDecimalFormatter(Function<BigDecimal, BigDecimal> wholeFunc) {
+        this.func = wholeFunc;
+    }
+
+    public static Builder builder() {
+        return new Builder();
+    }
+
+    public String toPlainString(BigDecimal value) {
+        final BigDecimal finalDecimal = func == null ? value : func.apply(value);
+        return finalDecimal.toPlainString();
+    }
+
+    public String toEngineeringString(BigDecimal value) {
+        final BigDecimal finalDecimal = func == null ? value : func.apply(value);
+        return finalDecimal.toEngineeringString();
+    }
+
+    public static class Builder {
+        private Function<BigDecimal, BigDecimal> wholeFunc;
+
+        private Builder() {
+        }
+
+        public Builder setScale(int newScale, RoundingMode roundingMode) {
+            final Function<BigDecimal, BigDecimal> func = value -> value.setScale(newScale, roundingMode);
+            if (wholeFunc == null) {
+                wholeFunc = func;
+            } else {
+                wholeFunc = func.andThen(func);
+            }
+            return this;
+        }
+
+        public Builder stripTrailingZeros() {
+            if (wholeFunc == null) {
+                wholeFunc = BigDecimal::stripTrailingZeros;
+            } else {
+                wholeFunc = wholeFunc.andThen(BigDecimal::stripTrailingZeros);
+            }
+            return this;
+        }
+
+        public BigDecimalFormatter build() {
+            return new BigDecimalFormatter(wholeFunc);
+        }
     }
 }