feat: add java.sql.Clob converter

fesod-sheet/src/main/java/org/apache/fesod/sheet/converters/DefaultConverterLoader.java

@@ -44,6 +44,7 @@
 import org.apache.fesod.sheet.converters.byteconverter.ByteBooleanConverter;
 import org.apache.fesod.sheet.converters.byteconverter.ByteNumberConverter;
 import org.apache.fesod.sheet.converters.byteconverter.ByteStringConverter;
+import org.apache.fesod.sheet.converters.clob.ClobStringConverter;
 import org.apache.fesod.sheet.converters.date.DateDateConverter;
 import org.apache.fesod.sheet.converters.date.DateNumberConverter;
 import org.apache.fesod.sheet.converters.date.DateStringConverter;
@@ -111,6 +112,8 @@ private static void initAllConverter() {
         putAllConverter(new ByteNumberConverter());
         putAllConverter(new ByteStringConverter());
 
+        putAllConverter(new ClobStringConverter());
+
         putAllConverter(new DateNumberConverter());
         putAllConverter(new DateStringConverter());
 
@@ -166,6 +169,7 @@ private static void initDefaultWriteConverter() {
         putWriteConverter(new LongNumberConverter());
         putWriteConverter(new ShortNumberConverter());
         putWriteConverter(new StringStringConverter());
+        putWriteConverter(new ClobStringConverter());
         putWriteConverter(new FileImageConverter());
         putWriteConverter(new InputStreamImageConverter());
         putWriteConverter(new ByteArrayImageConverter());
@@ -187,6 +191,7 @@ private static void initDefaultWriteConverter() {
         putWriteStringConverter(new LongStringConverter());
         putWriteStringConverter(new ShortStringConverter());
         putWriteStringConverter(new StringStringConverter());
+        putWriteStringConverter(new ClobStringConverter());
         defaultWriteConverter = Collections.unmodifiableMap(defaultWriteConverter);
     }
 

fesod-sheet/src/main/java/org/apache/fesod/sheet/converters/clob/ClobStringConverter.java

@@ -0,0 +1,69 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.apache.fesod.sheet.converters.clob;
+
+import java.io.Reader;
+import java.sql.Clob;
+import javax.sql.rowset.serial.SerialClob;
+import org.apache.fesod.sheet.converters.Converter;
+import org.apache.fesod.sheet.enums.CellDataTypeEnum;
+import org.apache.fesod.sheet.metadata.GlobalConfiguration;
+import org.apache.fesod.sheet.metadata.data.ReadCellData;
+import org.apache.fesod.sheet.metadata.data.WriteCellData;
+import org.apache.fesod.sheet.metadata.property.ExcelContentProperty;
+
+/**
+ * Clob and string converter. Clob data is represented as a string cell; reads return a
+ * {@link SerialClob} so callers receive a usable, detached JDBC Clob value.
+ */
+public class ClobStringConverter implements Converter<Clob> {
+    @Override
+    public Class<?> supportJavaTypeKey() {
+        return Clob.class;
+    }
+
+    @Override
+    public CellDataTypeEnum supportExcelTypeKey() {
+        return CellDataTypeEnum.STRING;
+    }
+
+    @Override
+    public Clob convertToJavaData(
+            ReadCellData<?> cellData, ExcelContentProperty contentProperty, GlobalConfiguration globalConfiguration)
+            throws Exception {
+        // Materialize cell text into a detached JDBC Clob, avoiding a database-specific Clob implementation.
+        return new SerialClob(cellData.getStringValue().toCharArray());
+    }
+
+    @Override
+    public WriteCellData<?> convertToExcelData(
+            Clob value, ExcelContentProperty contentProperty, GlobalConfiguration globalConfiguration)
+            throws Exception {
+        StringBuilder text = new StringBuilder();
+        char[] buffer = new char[4096];
+        try (Reader reader = value.getCharacterStream()) {
+            int count;
+            while ((count = reader.read(buffer)) != -1) {
+                text.append(buffer, 0, count);
+            }
+        }
+        return new WriteCellData<>(text.toString());
+    }
+}

fesod-sheet/src/test/java/org/apache/fesod/sheet/converters/DefaultConverterLoaderTest.java

@@ -19,9 +19,11 @@
 
 package org.apache.fesod.sheet.converters;
 
+import java.sql.Clob;
 import java.time.LocalTime;
 import java.util.Map;
 import org.apache.fesod.sheet.converters.ConverterKeyBuild.ConverterKey;
+import org.apache.fesod.sheet.converters.clob.ClobStringConverter;
 import org.apache.fesod.sheet.converters.localtime.LocalTimeDateConverter;
 import org.apache.fesod.sheet.converters.localtime.LocalTimeNumberConverter;
 import org.apache.fesod.sheet.converters.localtime.LocalTimeStringConverter;
@@ -67,6 +69,21 @@ void loadConvertersRegistersLocalTimeFamily() {
                 writeConverter.get(ConverterKeyBuild.buildKey(LocalTime.class, CellDataTypeEnum.STRING)));
     }
 
+    @Test
+    void loadConvertersRegistersClobStringConverter() {
+        Map<ConverterKey, Converter<?>> allConverter = DefaultConverterLoader.loadAllConverter();
+        Assertions.assertInstanceOf(
+                ClobStringConverter.class,
+                allConverter.get(ConverterKeyBuild.buildKey(Clob.class, CellDataTypeEnum.STRING)));
+
+        Map<ConverterKey, Converter<?>> writeConverter = DefaultConverterLoader.loadDefaultWriteConverter();
+        Assertions.assertInstanceOf(
+                ClobStringConverter.class, writeConverter.get(ConverterKeyBuild.buildKey(Clob.class)));
+        Assertions.assertInstanceOf(
+                ClobStringConverter.class,
+                writeConverter.get(ConverterKeyBuild.buildKey(Clob.class, CellDataTypeEnum.STRING)));
+    }
+
     private static void assertLoadIsImmutableAndCopyIsMutable(
             Map<ConverterKey, Converter<?>> loaded, Map<ConverterKey, Converter<?>> copy) {
         Map.Entry<ConverterKey, Converter<?>> entry =

fesod-sheet/src/test/java/org/apache/fesod/sheet/converters/clob/ClobStringConverterTest.java

@@ -0,0 +1,60 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.apache.fesod.sheet.converters.clob;
+
+import java.sql.Clob;
+import javax.sql.rowset.serial.SerialClob;
+import org.apache.fesod.sheet.enums.CellDataTypeEnum;
+import org.apache.fesod.sheet.metadata.GlobalConfiguration;
+import org.apache.fesod.sheet.metadata.data.ReadCellData;
+import org.apache.fesod.sheet.metadata.data.WriteCellData;
+import org.apache.fesod.sheet.testkit.Tags;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Tag;
+import org.junit.jupiter.api.Test;
+
+@Tag(Tags.UNIT)
+class ClobStringConverterTest {
+    private static final GlobalConfiguration GLOBAL_CONFIGURATION = new GlobalConfiguration();
+    private final ClobStringConverter converter = new ClobStringConverter();
+
+    @Test
+    void supportKeys() {
+        Assertions.assertEquals(Clob.class, converter.supportJavaTypeKey());
+        Assertions.assertEquals(CellDataTypeEnum.STRING, converter.supportExcelTypeKey());
+    }
+
+    @Test
+    void convertsCellStringToDetachedClob() throws Exception {
+        Clob actual = converter.convertToJavaData(new ReadCellData<>("Large text 字符"), null, GLOBAL_CONFIGURATION);
+
+        Assertions.assertEquals("Large text 字符", actual.getSubString(1, (int) actual.length()));
+    }
+
+    @Test
+    void convertsClobCharacterStreamToCellString() throws Exception {
+        Clob value = new SerialClob("Large text 字符".toCharArray());
+
+        WriteCellData<?> written = converter.convertToExcelData(value, null, GLOBAL_CONFIGURATION);
+
+        Assertions.assertEquals(CellDataTypeEnum.STRING, written.getType());
+        Assertions.assertEquals("Large text 字符", written.getStringValue());
+    }
+}