fixes mybatis#1351 Allow ReuseExecutor to reuse statement.

- Closing Statement may be an executor's responsibility.
- Using Cursor now requires drivers that support Statement#closeOnCompletion() (JDBC 4.1+).

src/main/java/org/apache/ibatis/cursor/defaults/DefaultCursor.java

@@ -25,7 +25,6 @@
 
 import java.sql.ResultSet;
 import java.sql.SQLException;
-import java.sql.Statement;
 import java.util.Iterator;
 import java.util.NoSuchElementException;
 
@@ -113,12 +112,7 @@ public void close() {
     ResultSet rs = rsw.getResultSet();
     try {
       if (rs != null) {
-        Statement statement = rs.getStatement();
-
         rs.close();
-        if (statement != null) {
-          statement.close();
-        }
       }
       status = CursorStatus.CLOSED;
     } catch (SQLException e) {

src/main/java/org/apache/ibatis/executor/BatchExecutor.java

@@ -103,6 +103,7 @@ protected <E> Cursor<E> doQueryCursor(MappedStatement ms, Object parameter, RowB
     StatementHandler handler = configuration.newStatementHandler(wrapper, ms, parameter, rowBounds, null, boundSql);
     Connection connection = getConnection(ms.getStatementLog());
     Statement stmt = handler.prepare(connection, transaction.getTimeout());
+    stmt.closeOnCompletion();
     handler.parameterize(stmt);
     return handler.<E>queryCursor(stmt);
   }

src/main/java/org/apache/ibatis/executor/SimpleExecutor.java

@@ -71,6 +71,7 @@ protected <E> Cursor<E> doQueryCursor(MappedStatement ms, Object parameter, RowB
     Configuration configuration = ms.getConfiguration();
     StatementHandler handler = configuration.newStatementHandler(wrapper, ms, parameter, rowBounds, null, boundSql);
     Statement stmt = prepareStatement(handler, ms.getStatementLog());
+    stmt.closeOnCompletion();
     return handler.<E>queryCursor(stmt);
   }
 

src/test/java/org/apache/ibatis/submitted/cursor_simple/PostgresCursorTest.java

@@ -0,0 +1,96 @@
+/**
+ *    Copyright 2009-2018 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.
+ *    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.apache.ibatis.submitted.cursor_simple;
+
+import static org.junit.Assert.*;
+
+import java.io.IOException;
+import java.nio.file.Paths;
+import java.util.Collections;
+import java.util.Iterator;
+
+import org.apache.ibatis.BaseDataTest;
+import org.apache.ibatis.cursor.Cursor;
+import org.apache.ibatis.datasource.unpooled.UnpooledDataSource;
+import org.apache.ibatis.mapping.Environment;
+import org.apache.ibatis.session.Configuration;
+import org.apache.ibatis.session.ExecutorType;
+import org.apache.ibatis.session.SqlSession;
+import org.apache.ibatis.session.SqlSessionFactory;
+import org.apache.ibatis.session.SqlSessionFactoryBuilder;
+import org.apache.ibatis.test.EmbeddedPostgresqlTests;
+import org.apache.ibatis.transaction.jdbc.JdbcTransactionFactory;
+import org.junit.AfterClass;
+import org.junit.BeforeClass;
+import org.junit.Test;
+import org.junit.experimental.categories.Category;
+
+import ru.yandex.qatools.embed.postgresql.EmbeddedPostgres;
+import ru.yandex.qatools.embed.postgresql.util.SocketUtil;
+
+@Category(EmbeddedPostgresqlTests.class)
+public class PostgresCursorTest {
+
+  private static final EmbeddedPostgres postgres = new EmbeddedPostgres();
+
+  private static SqlSessionFactory sqlSessionFactory;
+
+  @BeforeClass
+  public static void setUp() throws Exception {
+    // Launch PostgreSQL server. Download / unarchive if necessary.
+    String url = postgres.start(
+      EmbeddedPostgres.cachedRuntimeConfig(Paths.get(System.getProperty("java.io.tmpdir"), "pgembed")), "localhost",
+      SocketUtil.findFreePort(), "cursor_simple", "postgres", "root", Collections.emptyList());
+
+    Configuration configuration = new Configuration();
+    Environment environment = new Environment("development", new JdbcTransactionFactory(), new UnpooledDataSource(
+      "org.postgresql.Driver", url, null));
+    configuration.setEnvironment(environment);
+    configuration.addMapper(Mapper.class);
+    sqlSessionFactory = new SqlSessionFactoryBuilder().build(configuration);
+
+    BaseDataTest.runScript(sqlSessionFactory.getConfiguration().getEnvironment().getDataSource(),
+      "org/apache/ibatis/submitted/cursor_simple/CreateDB.sql");
+  }
+
+  @AfterClass
+  public static void tearDown() {
+    postgres.stop();
+  }
+
+  @Test
+  public void shouldBeAbleToReuseStatement() throws IOException {
+    // #1351
+    try (SqlSession sqlSession = sqlSessionFactory.openSession(ExecutorType.REUSE)) {
+      Mapper mapper = sqlSession.getMapper(Mapper.class);
+      {
+        Cursor<User> usersCursor = mapper.getAllUsers();
+        Iterator<User> iterator = usersCursor.iterator();
+        User user = iterator.next();
+        assertEquals("User1", user.getName());
+        usersCursor.close();
+      }
+      {
+        Cursor<User> usersCursor = mapper.getAllUsers();
+        Iterator<User> iterator = usersCursor.iterator();
+        User user = iterator.next();
+        assertEquals("User1", user.getName());
+        usersCursor.close();
+      }
+    }
+  }
+}