Supports ConversionService on SingleColumnRowMapper

Issue: SPR-16483

spring-jdbc/src/main/java/org/springframework/jdbc/core/SingleColumnRowMapper.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2017 the original author or authors.
+ * Copyright 2002-2018 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -20,6 +20,8 @@ import java.sql.ResultSet;
 import java.sql.ResultSetMetaData;
 import java.sql.SQLException;
 
+import org.springframework.core.convert.ConversionService;
+import org.springframework.core.convert.support.DefaultConversionService;
 import org.springframework.dao.TypeMismatchDataAccessException;
 import org.springframework.jdbc.IncorrectResultSetColumnCountException;
 import org.springframework.jdbc.support.JdbcUtils;
@@ -37,6 +39,7 @@ import org.springframework.util.NumberUtils;
  * and converted into the specified target type.
  *
  * @author Juergen Hoeller
+ * @author Kazuki Shimizu
  * @since 1.2
  * @see JdbcTemplate#queryForList(String, Class)
  * @see JdbcTemplate#queryForObject(String, Class)
@@ -46,6 +49,8 @@ public class SingleColumnRowMapper<T> implements RowMapper<T> {
 	@Nullable
 	private Class<?> requiredType;
 
+	@Nullable
+	private ConversionService conversionService = DefaultConversionService.getSharedInstance();
 
 	/**
 	 * Create a new {@code SingleColumnRowMapper} for bean-style configuration.
@@ -74,6 +79,15 @@ public class SingleColumnRowMapper<T> implements RowMapper<T> {
 		this.requiredType = ClassUtils.resolvePrimitiveIfNecessary(requiredType);
 	}
 
+	/**
+	 * Set a {@link ConversionService} for converting a fetched value.
+	 * <p>Default is the {@link DefaultConversionService}.
+	 * @since 5.0.4
+	 * @see DefaultConversionService#getSharedInstance
+	 */
+	public void setConversionService(@Nullable ConversionService conversionService) {
+		this.conversionService = conversionService;
+	}
 
 	/**
 	 * Extract a value for the single column in the current row.
@@ -164,7 +178,8 @@ public class SingleColumnRowMapper<T> implements RowMapper<T> {
 	 * <p>If the required type is String, the value will simply get stringified
 	 * via {@code toString()}. In case of a Number, the value will be
 	 * converted into a Number, either through number conversion or through
-	 * String parsing (depending on the value type).
+	 * String parsing (depending on the value type). Otherwise, the value will
+	 * be converted to a required type using the {@link ConversionService}.
 	 * @param value the column value as extracted from {@code getColumnValue()}
 	 * (never {@code null})
 	 * @param requiredType the type that each result object is expected to match
@@ -173,6 +188,7 @@ public class SingleColumnRowMapper<T> implements RowMapper<T> {
 	 * @see #getColumnValue(java.sql.ResultSet, int, Class)
 	 */
 	@SuppressWarnings("unchecked")
+	@Nullable
 	protected Object convertValueToRequiredType(Object value, Class<?> requiredType) {
 		if (String.class == requiredType) {
 			return value.toString();
@@ -187,6 +203,9 @@ public class SingleColumnRowMapper<T> implements RowMapper<T> {
 				return NumberUtils.parseNumber(value.toString(),(Class<Number>) requiredType);
 			}
 		}
+		else if (this.conversionService != null && this.conversionService.canConvert(value.getClass(), requiredType)) {
+			return this.conversionService.convert(value, requiredType);
+		}
 		else {
 			throw new IllegalArgumentException(
 					"Value [" + value + "] is of type [" + value.getClass().getName() +
@@ -205,4 +224,17 @@ public class SingleColumnRowMapper<T> implements RowMapper<T> {
 		return new SingleColumnRowMapper<>(requiredType);
 	}
 
+	/**
+	 * Static factory method to create a new {@code SingleColumnRowMapper}
+	 * (with the required type specified only once).
+	 * @param requiredType the type that each result object is expected to match
+	 * @param conversionService the {@link ConversionService} for converting a fetched value
+	 * @since 5.0.4
+	 */
+	public static <T> SingleColumnRowMapper<T> newInstance(Class<T> requiredType, @Nullable ConversionService conversionService) {
+		SingleColumnRowMapper<T> rowMapper = newInstance(requiredType);
+		rowMapper.setConversionService(conversionService);
+		return rowMapper;
+	}
+
 }

spring-jdbc/src/test/java/org/springframework/jdbc/core/SingleColumnRowMapperTest.java

@@ -0,0 +1,107 @@
+/*
+ * Copyright 2002-2018 the original author or authors.
+ *
+ * Licensed 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.springframework.jdbc.core;
+
+import java.sql.ResultSet;
+import java.sql.ResultSetMetaData;
+import java.sql.SQLException;
+import java.sql.SQLFeatureNotSupportedException;
+import java.sql.Timestamp;
+import java.time.LocalDateTime;
+
+import org.junit.Test;
+import org.springframework.core.convert.support.DefaultConversionService;
+import org.springframework.dao.TypeMismatchDataAccessException;
+
+import static org.mockito.BDDMockito.*;
+import static org.junit.Assert.*;
+
+/**
+ * Tests for {@link SingleColumnRowMapper}.
+ *
+ * @author Kazuki Shimizu
+ * @since 5.0.4
+ */
+public class SingleColumnRowMapperTest {
+
+	@Test // SPR-16483
+	public void useDefaultConversionService() throws SQLException {
+		Timestamp timestamp = new Timestamp(0);
+
+		SingleColumnRowMapper<LocalDateTime> rowMapper = SingleColumnRowMapper.newInstance(LocalDateTime.class);
+
+		ResultSet resultSet = mock(ResultSet.class);
+		ResultSetMetaData metaData = mock(ResultSetMetaData.class);
+		given(metaData.getColumnCount()).willReturn(1);
+		given(resultSet.getMetaData()).willReturn(metaData);
+		given(resultSet.getObject(1, LocalDateTime.class))
+				.willThrow(new SQLFeatureNotSupportedException());
+		given(resultSet.getTimestamp(1)).willReturn(timestamp);
+
+		LocalDateTime actualLocalDateTime = rowMapper.mapRow(resultSet, 1);
+
+		assertEquals(timestamp.toLocalDateTime(), actualLocalDateTime);
+	}
+
+	@Test // SPR-16483
+	public void useCustomConversionService() throws SQLException {
+		Timestamp timestamp = new Timestamp(0);
+
+		DefaultConversionService myConversionService = new DefaultConversionService();
+		myConversionService.addConverter(Timestamp.class, MyLocalDateTime.class,
+				source -> new MyLocalDateTime(source.toLocalDateTime()));
+		SingleColumnRowMapper<MyLocalDateTime> rowMapper =
+				SingleColumnRowMapper.newInstance(MyLocalDateTime.class, myConversionService);
+
+		ResultSet resultSet = mock(ResultSet.class);
+		ResultSetMetaData metaData = mock(ResultSetMetaData.class);
+		given(metaData.getColumnCount()).willReturn(1);
+		given(resultSet.getMetaData()).willReturn(metaData);
+		given(resultSet.getObject(1, MyLocalDateTime.class))
+				.willThrow(new SQLFeatureNotSupportedException());
+		given(resultSet.getObject(1)).willReturn(timestamp);
+
+		MyLocalDateTime actualMyLocalDateTime = rowMapper.mapRow(resultSet, 1);
+
+		assertNotNull(actualMyLocalDateTime);
+		assertEquals(timestamp.toLocalDateTime(), actualMyLocalDateTime.value);
+	}
+
+	@Test(expected = TypeMismatchDataAccessException.class) // SPR-16483
+	public void doesNotUseConversionService() throws SQLException {
+		SingleColumnRowMapper<LocalDateTime> rowMapper =
+				SingleColumnRowMapper.newInstance(LocalDateTime.class, null);
+
+		ResultSet resultSet = mock(ResultSet.class);
+		ResultSetMetaData metaData = mock(ResultSetMetaData.class);
+		given(metaData.getColumnCount()).willReturn(1);
+		given(resultSet.getMetaData()).willReturn(metaData);
+		given(resultSet.getObject(1, LocalDateTime.class))
+				.willThrow(new SQLFeatureNotSupportedException());
+		given(resultSet.getTimestamp(1)).willReturn(new Timestamp(0));
+
+		rowMapper.mapRow(resultSet, 1);
+	}
+
+	private static class MyLocalDateTime {
+		private final LocalDateTime value;
+		private MyLocalDateTime(LocalDateTime value) {
+			this.value = value;
+		}
+	}
+
+}