Spring JdbcTemplate with Java 8 Streams

This repository contains example code for how one might use Spring's JdbcTemplate with the Java 8 Stream API.

To integrate it in your own project clone this repository in a subdirectory (this way you can always pull for updates) and integrate it in your build. If you use maven use the include tag of the maven-compiler-plugin. To run it in your IDE ensure to set the additional Sources Root.

Sample code

• JdbcStream.streamableQuery(): an extension of JdbcTemplate to make a Closeable streamable query. This gets into the protected guts of JdbcTemplate to manage a connection's lifetime, and becomes a resource which must be closed.
• JdbcStream.streamQuery(): a callback-style query interface allowing stream processing inside JdbcTemplate's own resource management system. This version will not work for empty result sets.
• JdbcStreamApplication.streamer: a bean implementing streamQuery() as a consumer of a JdbcTemplate. This one correctly handles empty result sets, and is the basis of the [gist] and [blog post] which this code fed.

There's a performance test suite which will go out of memory for query methods which inadvertently cache the entire result set in memory, and a basic test suite demonstrating the streaming code performs as expected.

The test cases show what not to do with this interface: they reimplement trivial SQL queries in Java code.