Merge branch 'bugfix' into developing

# Conflicts:
#	src/main/java/com/alibaba/excel/converters/DefaultConverterLoader.java

src/main/java/com/alibaba/excel/converters/DefaultConverterLoader.java

@@ -5,6 +5,7 @@ import java.util.Map;
 import com.alibaba.excel.converters.bigdecimal.BigDecimalBooleanConverter;
 import com.alibaba.excel.converters.bigdecimal.BigDecimalNumberConverter;
 import com.alibaba.excel.converters.bigdecimal.BigDecimalStringConverter;
+import com.alibaba.excel.converters.biginteger.BigIntegerStringConverter;
 import com.alibaba.excel.converters.booleanconverter.BooleanBooleanConverter;
 import com.alibaba.excel.converters.booleanconverter.BooleanNumberConverter;
 import com.alibaba.excel.converters.booleanconverter.BooleanStringConverter;
@@ -95,6 +96,8 @@ public class DefaultConverterLoader {
         putAllConverter(new StringNumberConverter());
         putAllConverter(new StringStringConverter());
         putAllConverter(new StringErrorConverter());
+
+        putAllConverter(new BigIntegerStringConverter());
     }
 
     private static void initDefaultWriteConverter() {
@@ -114,6 +117,7 @@ public class DefaultConverterLoader {
         putWriteConverter(new ByteArrayImageConverter());
         putWriteConverter(new BoxingByteArrayImageConverter());
         putWriteConverter(new UrlImageConverter());
+        putWriteConverter(new BigIntegerStringConverter());
 
         // In some cases, it must be converted to string
         putWriteStringConverter(new BigDecimalStringConverter());

src/main/java/com/alibaba/excel/converters/biginteger/BigIntegerStringConverter.java

@@ -0,0 +1,42 @@
+package com.alibaba.excel.converters.biginteger;
+
+import java.math.BigDecimal;
+import java.math.BigInteger;
+import java.text.ParseException;
+
+import com.alibaba.excel.converters.Converter;
+import com.alibaba.excel.enums.CellDataTypeEnum;
+import com.alibaba.excel.metadata.CellData;
+import com.alibaba.excel.metadata.GlobalConfiguration;
+import com.alibaba.excel.metadata.property.ExcelContentProperty;
+import com.alibaba.excel.util.NumberUtils;
+
+/**
+ * BigDecimal and string converter
+ *
+ * @author Jiaju Zhuang
+ */
+public class BigIntegerStringConverter implements Converter<BigInteger> {
+
+    @Override
+    public Class supportJavaTypeKey() {
+        return BigInteger.class;
+    }
+
+    @Override
+    public CellDataTypeEnum supportExcelTypeKey() {
+        return CellDataTypeEnum.STRING;
+    }
+
+    @Override
+    public BigInteger convertToJavaData(CellData cellData, ExcelContentProperty contentProperty,
+                                        GlobalConfiguration globalConfiguration) throws ParseException {
+        return NumberUtils.parseBigDecimal(cellData.getStringValue(), contentProperty).toBigInteger();
+    }
+
+    @Override
+    public CellData convertToExcelData(BigInteger value, ExcelContentProperty contentProperty,
+                                       GlobalConfiguration globalConfiguration) {
+        return NumberUtils.formatToCellData(value, contentProperty);
+    }
+}