add a first row data converter

Author: uaihebert

src/main/java/org/springframework/data/r2dbc/repository/query/RowDataConverter.java

@@ -0,0 +1,127 @@
+/*
+ * Copyright 2019 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.data.r2dbc.repository.query;
+
+import io.r2dbc.spi.Row;
+import org.springframework.core.convert.converter.Converter;
+import org.springframework.core.convert.converter.ConverterFactory;
+import org.springframework.data.r2dbc.repository.query.RowDataConverter.RowToNumberConverterFactory.RowToStringConverter;
+import org.springframework.util.Assert;
+import org.springframework.util.NumberUtils;
+
+import java.net.InetAddress;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Date;
+import java.util.List;
+import java.util.UUID;
+
+/**
+ * Base class for row data converter.
+ *
+ * @author Hebert Coelho
+ */
+abstract class RowDataConverter {
+    private RowDataConverter() {
+    }
+
+    static Collection<Object> getConvertersToRegister() {
+        List<Object> converters = new ArrayList<>();
+
+        converters.add(RowToBooleanConverter.INSTANCE);
+        converters.add(RowToDateConverter.INSTANCE);
+        converters.add(RowToInetAddressConverter.INSTANCE);
+        converters.add(RowToNumberConverterFactory.INSTANCE);
+        converters.add(RowToStringConverter.INSTANCE);
+        converters.add(RowToUuidConverter.INSTANCE);
+
+        return converters;
+    }
+
+    public enum RowToBooleanConverter implements Converter<Row, Boolean> {
+        INSTANCE;
+
+        @Override
+        public Boolean convert(Row row) {
+            return (Boolean) row.get(0);
+        }
+    }
+
+    public enum RowToDateConverter implements Converter<Row, Date> {
+        INSTANCE;
+
+        @Override
+        public Date convert(Row row) {
+            return (Date) row.get(0);
+        }
+    }
+
+    public enum RowToInetAddressConverter implements Converter<Row, InetAddress> {
+        INSTANCE;
+
+        @Override
+        public InetAddress convert(Row row) {
+            return (InetAddress) row.get(0);
+        }
+    }
+
+    public enum RowToNumberConverterFactory implements ConverterFactory<Row, Number> {
+
+        INSTANCE;
+
+        @Override
+        public <T extends Number> Converter<Row, T> getConverter(Class<T> targetType) {
+            Assert.notNull(targetType, "Target type must not be null");
+            return new RowToNumber<>(targetType);
+        }
+
+        private static final class RowToNumber<T extends Number> implements Converter<Row, T> {
+            private final Class<T> targetType;
+
+            RowToNumber(Class<T> targetType) {
+                this.targetType = targetType;
+            }
+
+            @Override
+            public T convert(Row source) {
+
+                Object object = source.get(0);
+
+                return (object != null ? NumberUtils.convertNumberToTargetClass((Number) object, this.targetType) : null);
+            }
+        }
+
+        public enum RowToStringConverter implements Converter<Row, String> {
+            INSTANCE;
+
+            @Override
+            public String convert(Row row) {
+                return row.get(0).toString();
+            }
+        }
+    }
+
+    public enum RowToUuidConverter implements Converter<Row, UUID> {
+        INSTANCE;
+
+        @Override
+        public UUID convert(Row row) {
+            return (UUID) row.get(0);
+        }
+    }
+
+}