Polishing.

Align R2dbcCustomConversions creation with configurer pattern.

See #1828
Original pull request #2062

spring-data-r2dbc/src/main/java/org/springframework/data/r2dbc/convert/R2dbcCustomConversions.java

@@ -6,10 +6,18 @@ import java.util.Collection;
 import java.util.Collections;
 import java.util.Date;
 import java.util.List;
+import java.util.function.Consumer;
 
+import org.springframework.core.convert.converter.Converter;
+import org.springframework.core.convert.converter.ConverterFactory;
+import org.springframework.core.convert.converter.GenericConverter;
+import org.springframework.data.convert.ConverterBuilder;
 import org.springframework.data.convert.CustomConversions;
 import org.springframework.data.r2dbc.dialect.R2dbcDialect;
 import org.springframework.data.r2dbc.mapping.R2dbcSimpleTypeHolder;
+import org.springframework.data.relational.core.dialect.Dialect;
+import org.springframework.lang.Contract;
+import org.springframework.util.Assert;
 
 /**
  * Value object to capture custom conversion. {@link R2dbcCustomConversions} also act as factory for
@@ -70,11 +78,27 @@ public class R2dbcCustomConversions extends CustomConversions {
 	 * @since 1.2
 	 */
 	public static R2dbcCustomConversions of(R2dbcDialect dialect, Collection<?> converters) {
+		return create(dialect, configurer -> configurer.registerConverters(converters));
+	}
+
+	/**
+	 * Create a new {@link R2dbcCustomConversions} instance using the given {@link R2dbcDialect} and
+	 * {@link R2dbcConverterConfigurer} callback to configure converters.
+	 *
+	 * @param dialect the {@link Dialect} to use, must not be {@literal null}.
+	 * @param configurer the configurer callback to configure converters, must not be {@literal null}.
+	 * @return a new {@link R2dbcCustomConversions} instance configured from the given dialect and configured converters.
+	 * @since 4.0
+	 */
+	public static R2dbcCustomConversions create(R2dbcDialect dialect, Consumer<R2dbcConverterConfigurer> configurer) {
 
-		List<Object> storeConverters = new ArrayList<>(dialect.getConverters());
+		Assert.notNull(dialect, "Dialect must not be null");
-		storeConverters.addAll(R2dbcCustomConversions.STORE_CONVERTERS);
+		Assert.notNull(configurer, "R2dbcConverterConfigurer Consumer must not be null");
 
-		return new R2dbcCustomConversions(StoreConversions.of(dialect.getSimpleTypeHolder(), storeConverters), converters);
+		R2dbcConverterConfigurer converterConfigurer = R2dbcConverterConfigurer.from(dialect);
+		configurer.accept(converterConfigurer);
+
+		return new R2dbcCustomConversions(converterConfigurer.createConfiguration());
 	}
 
 	static class R2dbcCustomConversionsConfiguration extends ConverterConfiguration {
@@ -92,4 +116,112 @@ public class R2dbcCustomConversions extends CustomConversions {
 			});
 		}
 	}
+
+	/**
+	 * {@link R2dbcConverterConfigurer} encapsulates creation of {@link R2dbcCustomConversionsConfiguration} with R2DBC
+	 * specifics.
+	 *
+	 * @author Mark Paluch
+	 * @since 4.0
+	 */
+	public static class R2dbcConverterConfigurer {
+
+		private final StoreConversions storeConversions;
+		private final List<Object> customConverters = new ArrayList<>();
+
+		private R2dbcConverterConfigurer(StoreConversions storeConversions) {
+			this.storeConversions = storeConversions;
+		}
+
+		/**
+		 * Create a {@link R2dbcConverterConfigurer} using the provided {@code dialect} and our own codecs for JSR-310
+		 * types.
+		 *
+		 * @param dialect must not be {@literal null}.
+		 * @return
+		 */
+		static R2dbcConverterConfigurer from(R2dbcDialect dialect) {
+
+			List<Object> converters = new ArrayList<>();
+			converters.addAll(dialect.getConverters());
+			converters.addAll(R2dbcCustomConversions.STORE_CONVERTERS);
+
+			StoreConversions storeConversions = StoreConversions.of(dialect.getSimpleTypeHolder(), converters);
+
+			return new R2dbcConverterConfigurer(storeConversions);
+		}
+
+		/**
+		 * Create a {@link R2dbcConverterConfigurer} using the provided {@code storeConversions}.
+		 *
+		 * @param storeConversions must not be {@literal null}.
+		 * @return
+		 */
+		static R2dbcConverterConfigurer from(StoreConversions storeConversions) {
+			return new R2dbcConverterConfigurer(storeConversions);
+		}
+
+		/**
+		 * Add a custom {@link Converter} implementation.
+		 *
+		 * @param converter must not be {@literal null}.
+		 * @return this.
+		 */
+		@Contract("_ -> this")
+		public R2dbcConverterConfigurer registerConverter(Converter<?, ?> converter) {
+
+			Assert.notNull(converter, "Converter must not be null");
+			customConverters.add(converter);
+			return this;
+		}
+
+		/**
+		 * Add {@link Converter converters}, {@link ConverterFactory factories}, {@link ConverterBuilder.ConverterAware
+		 * converter-aware objects}, and {@link GenericConverter generic converters}.
+		 *
+		 * @param converters must not be {@literal null} nor contain {@literal null} values.
+		 * @return this.
+		 */
+		@Contract("_ -> this")
+		public R2dbcConverterConfigurer registerConverters(Object... converters) {
+			return registerConverters(Arrays.asList(converters));
+		}
+
+		/**
+		 * Add {@link Converter converters}, {@link ConverterFactory factories}, {@link ConverterBuilder.ConverterAware
+		 * converter-aware objects}, and {@link GenericConverter generic converters}.
+		 *
+		 * @param converters must not be {@literal null} nor contain {@literal null} values.
+		 * @return this.
+		 */
+		@Contract("_ -> this")
+		public R2dbcConverterConfigurer registerConverters(Collection<?> converters) {
+
+			Assert.notNull(converters, "Converters must not be null");
+			Assert.noNullElements(converters, "Converters must not be null nor contain null values");
+
+			customConverters.addAll(converters);
+			return this;
+		}
+
+		/**
+		 * Add a custom {@link ConverterFactory} implementation.
+		 *
+		 * @param converterFactory must not be {@literal null}.
+		 * @return this.
+		 */
+		@Contract("_ -> this")
+		public R2dbcConverterConfigurer registerConverterFactory(ConverterFactory<?, ?> converterFactory) {
+
+			Assert.notNull(converterFactory, "ConverterFactory must not be null");
+			customConverters.add(converterFactory);
+			return this;
+		}
+
+		ConverterConfiguration createConfiguration() {
+			return new R2dbcCustomConversionsConfiguration(storeConversions, this.customConverters);
+		}
+
+	}
+
 }