SqlParameterSource interface exposes parameter names

Includes default implementations of getSqlType and getTypeName.

Issue: SPR-16361

spring-jdbc/src/main/java/org/springframework/jdbc/core/namedparam/BeanPropertySqlParameterSource.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.
@@ -73,6 +73,26 @@ public class BeanPropertySqlParameterSource extends AbstractSqlParameterSource {
 		}
 	}
 
+	/**
+	 * Derives a default SQL type from the corresponding property type.
+	 * @see org.springframework.jdbc.core.StatementCreatorUtils#javaTypeToSqlParameterType
+	 */
+	@Override
+	public int getSqlType(String paramName) {
+		int sqlType = super.getSqlType(paramName);
+		if (sqlType != TYPE_UNKNOWN) {
+			return sqlType;
+		}
+		Class<?> propType = this.beanWrapper.getPropertyType(paramName);
+		return StatementCreatorUtils.javaTypeToSqlParameterType(propType);
+	}
+
+	@Override
+	@Nullable
+	public String[] getParameterNames() {
+		return getReadablePropertyNames();
+	}
+
 	/**
 	 * Provide access to the property names of the wrapped bean.
 	 * Uses support provided in the {@link PropertyAccessor} interface.
@@ -92,18 +112,4 @@ public class BeanPropertySqlParameterSource extends AbstractSqlParameterSource {
 		return this.propertyNames;
 	}
 
-	/**
-	 * Derives a default SQL type from the corresponding property type.
-	 * @see org.springframework.jdbc.core.StatementCreatorUtils#javaTypeToSqlParameterType
-	 */
-	@Override
-	public int getSqlType(String paramName) {
-		int sqlType = super.getSqlType(paramName);
-		if (sqlType != TYPE_UNKNOWN) {
-			return sqlType;
-		}
-		Class<?> propType = this.beanWrapper.getPropertyType(paramName);
-		return StatementCreatorUtils.javaTypeToSqlParameterType(propType);
-	}
-
 }

spring-jdbc/src/main/java/org/springframework/jdbc/core/namedparam/EmptySqlParameterSource.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2013 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.
@@ -54,4 +54,10 @@ public class EmptySqlParameterSource implements SqlParameterSource {
 		return null;
 	}
 
+	@Override
+	@Nullable
+	public String[] getParameterNames() {
+		return null;
+	}
+
 }

spring-jdbc/src/main/java/org/springframework/jdbc/core/namedparam/MapSqlParameterSource.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.
@@ -23,6 +23,7 @@ import java.util.Map;
 import org.springframework.jdbc.core.SqlParameterValue;
 import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
+import org.springframework.util.StringUtils;
 
 /**
  * {@link SqlParameterSource} implementation that holds a given Map of parameters.
@@ -163,4 +164,10 @@ public class MapSqlParameterSource extends AbstractSqlParameterSource {
 		return this.values.get(paramName);
 	}
 
+	@Override
+	@Nullable
+	public String[] getParameterNames() {
+		return StringUtils.toStringArray(this.values.keySet());
+	}
+
 }

spring-jdbc/src/main/java/org/springframework/jdbc/core/namedparam/SqlParameterSource.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.
@@ -73,7 +73,9 @@ public interface SqlParameterSource {
 	 * or {@code TYPE_UNKNOWN} if not known
 	 * @see #TYPE_UNKNOWN
 	 */
-	int getSqlType(String paramName);
+	default int getSqlType(String paramName) {
+		return TYPE_UNKNOWN;
+	}
 
 	/**
 	 * Determine the type name for the specified named parameter.
@@ -82,6 +84,22 @@ public interface SqlParameterSource {
 	 * or {@code null} if not known
 	 */
 	@Nullable
-	String getTypeName(String paramName);
+	default String getTypeName(String paramName) {
+		return null;
+	}
+
+	/**
+	 * Extract all available parameter names if possible.
+	 * <p>This is an optional operation, primarily for use with
+	 * {@link org.springframework.jdbc.core.simple.SimpleJdbcInsert}
+	 * and {@link org.springframework.jdbc.core.simple.SimpleJdbcCall}.
+	 * @return the array of parameter names, or {@code null} if not determinable
+	 * @since 5.0.3
+	 * @see SqlParameterSourceUtils#extractCaseInsensitiveParameterNames
+	 */
+	@Nullable
+	default String[] getParameterNames() {
+		return null;
+	}
 
 }

spring-jdbc/src/main/java/org/springframework/jdbc/core/namedparam/SqlParameterSourceUtils.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.
@@ -117,14 +117,9 @@ public abstract class SqlParameterSourceUtils {
 	 */
 	public static Map<String, String> extractCaseInsensitiveParameterNames(SqlParameterSource parameterSource) {
 		Map<String, String> caseInsensitiveParameterNames = new HashMap<>();
-		if (parameterSource instanceof BeanPropertySqlParameterSource) {
-			String[] propertyNames = ((BeanPropertySqlParameterSource) parameterSource).getReadablePropertyNames();
-			for (String name : propertyNames) {
-				caseInsensitiveParameterNames.put(name.toLowerCase(), name);
-			}
-		}
-		else if (parameterSource instanceof MapSqlParameterSource) {
-			for (String name : ((MapSqlParameterSource) parameterSource).getValues().keySet()) {
+		String[] paramNames = parameterSource.getParameterNames();
+		if (paramNames != null) {
+			for (String name : paramNames) {
 				caseInsensitiveParameterNames.put(name.toLowerCase(), name);
 			}
 		}