[#4337] Add Stream<R> ResultQuery.stream()

jOOQ/src/main/java/org/jooq/ResultQuery.java

@@ -51,6 +51,9 @@ import java.util.Map;
 import java.util.Optional;
 import java.util.Set;
 import java.util.concurrent.ExecutorService;
+import java.util.stream.Stream;
+
+import javax.sql.DataSource;
 
 import org.jooq.conf.Settings;
 import org.jooq.exception.DataAccessException;
@@ -142,6 +145,31 @@ public interface ResultQuery<R extends Record> extends Query, Iterable<R> {
     @Override
     Iterator<R> iterator() throws DataAccessException;
 
+    /* [java-8] */
+    /**
+     * Stream this query.
+     * <p>
+     * This is essentially the same as {@link #fetchLazy()} but instead of
+     * returning a {@link Cursor}, a Java 8 {@link Stream} is returned. Clients
+     * should ensure the {@link Stream} is properly closed, e.g. in a
+     * try-with-resources statement:
+     * <p>
+     * <code><pre>
+     * try (Stream&lt;R> stream = query.stream()) {
+     *     // Do things with stream
+     * }
+     * </pre></code>
+     * <p>
+     * If users prefer more fluent style streaming of queries, {@link ResultSet}
+     * can be registered and closed via {@link ExecuteListener}, or via "smart"
+     * third-party {@link DataSource}s.
+     *
+     * @return The result.
+     * @throws DataAccessException if something went wrong executing the query
+     */
+    Stream<R> stream() throws DataAccessException;
+    /* [/java-8] */
+
     /**
      * Execute the query and "lazily" return the generated result.
      * <p>

jOOQ/src/main/java/org/jooq/impl/AbstractResultQuery.java

@@ -60,9 +60,13 @@ import java.util.List;
 import java.util.Map;
 import java.util.Optional;
 import java.util.Set;
+import java.util.Spliterator;
+import java.util.Spliterators;
 import java.util.concurrent.Callable;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Future;
+import java.util.stream.Stream;
+import java.util.stream.StreamSupport;
 
 import org.jooq.Configuration;
 import org.jooq.Converter;
@@ -77,6 +81,7 @@ import org.jooq.RecordMapper;
 import org.jooq.Result;
 import org.jooq.ResultQuery;
 import org.jooq.Table;
+import org.jooq.exception.DataAccessException;
 import org.jooq.tools.Convert;
 import org.jooq.tools.JooqLogger;
 
@@ -309,6 +314,22 @@ abstract class AbstractResultQuery<R extends Record> extends AbstractQuery imple
         return fetch().iterator();
     }
 
+    /* [java-8] */
+    @Override
+    public final Stream<R> stream() throws DataAccessException {
+        Cursor<R> c = fetchLazy();
+
+        return StreamSupport.stream(
+            Spliterators.spliterator(
+                c.iterator(),
+                0,
+                Spliterator.ORDERED | Spliterator.NONNULL
+            ),
+            false
+        ).onClose(() -> c.close());
+    }
+    /* [/java-8] */
+
     @Override
     public final Cursor<R> fetchLazy() {
         return fetchLazy(fetchSize);

jOOQ/src/main/java/org/jooq/impl/SelectImpl.java

@@ -54,6 +54,7 @@ import java.util.Map;
 import java.util.Optional;
 import java.util.Set;
 import java.util.concurrent.ExecutorService;
+import java.util.stream.Stream;
 
 import javax.annotation.Generated;
 
@@ -2359,6 +2360,13 @@ class SelectImpl<R extends Record, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11,
         return getDelegate().iterator();
     }
 
+    /* [java-8] */
+    @Override
+    public final Stream<R> stream() {
+        return getDelegate().stream();
+    }
+    /* [/java-8] */
+    
     @Override
     public final Cursor<R> fetchLazy() {
         return getDelegate().fetchLazy();