Work around JDK7 String#substring performance regression

String#substring has become significantly slower as of JDK 1.7.0_06 [1],
such that there are performance degradations by a factor of 100-1000 in
ResourceDatabasePopulator, especially for large SQL files.

This commit works around this problem by minimizing the substring scope
to the least amount possible to prevent unnecessary internal copying of
strings (which seems to cause the issue).

[1]: http://mail.openjdk.java.net/pipermail/core-libs-dev/2012-May/010257.html

Issue: SPR-9781

spring-jdbc/src/test/java/org/springframework/jdbc/datasource/init/DatabasePopulatorTests.java

@@ -238,4 +238,21 @@ public class DatabasePopulatorTests {
 
 		EasyMock.verify(populator);
 	}
+
+	/**
+	 * @see SPR-9781
+	 */
+	@Test(timeout = 1000)
+	public void executesHugeScriptInReasonableTime() throws SQLException {
+
+		databasePopulator.addScript(resourceLoader.getResource("db-schema.sql"));
+		databasePopulator.addScript(resourceLoader.getResource("db-test-data-huge.sql"));
+
+		Connection connection = db.getConnection();
+		try {
+			databasePopulator.populate(connection);
+		} finally {
+			connection.close();
+		}
+	}
 }