Clear parameters/batch/warnings, when statement is returned to cache

Author: rPraml

ebean-datasource/src/main/java/io/ebean/datasource/pool/PstmtCache.java

@@ -67,6 +67,15 @@ boolean returnStatement(ExtendedPreparedStatement stmt) {
     if (alreadyInCache != null) {
       return false;
     }
+    try {
+      // before putting a statement back to the cache, we will clear the parameters, batch and warnings
+      stmt.clearParameters();
+      stmt.clearBatch();
+      stmt.clearWarnings();
+    } catch (SQLException e) {
+      Log.error("Error clearing PreparedStatement", e);
+      return false;
+    }
     // add the returning prepared statement to the cache.
     // Note that the LRUCache will automatically close fully old unused
     // statements when the cache has hit its maximum size.

ebean-datasource/src/test/java/io/ebean/datasource/test/FactoryTest.java

@@ -3,10 +3,13 @@
 import io.ebean.datasource.DataSourceConfig;
 import io.ebean.datasource.DataSourceFactory;
 import io.ebean.datasource.DataSourcePool;
+import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.Test;
 
 import java.sql.Connection;
 import java.sql.PreparedStatement;
+import java.sql.ResultSet;
+import java.sql.SQLException;
 
 public class FactoryTest {
 
@@ -49,4 +52,39 @@ public void dataSourceFactory_get_createPool() throws Exception {
     }
 
   }
+
+
+  @Test
+  public void testPreparedStatement() throws Exception {
+
+    DataSourceConfig config = new DataSourceConfig();
+    config.setDriver("org.h2.Driver");
+    config.setUrl("jdbc:h2:mem:tests");
+    config.setUsername("sa");
+    config.setPassword("");
+
+    DataSourcePool pool = DataSourceFactory.create("test", config);
+    String sql = "select * from information_schema.settings where setting_name != ?";
+    try (Connection connection = pool.getConnection()) {
+      try (PreparedStatement stmt = connection.prepareStatement(sql)) {
+        stmt.executeQuery();
+        Assertions.fail("Not expected");
+      } catch (SQLException e) {
+        // expected: Parameter "#1" not set
+      }
+
+      try (PreparedStatement stmt = connection.prepareStatement(sql)) {
+        stmt.setString(1, "foo");
+        ResultSet rs = stmt.executeQuery();
+        rs.close();
+      }
+
+      try (PreparedStatement stmt = connection.prepareStatement(sql)) {
+        stmt.executeQuery();
+        Assertions.fail("Not expected");
+      } catch (SQLException e) {
+        // expected: Parameter "#1" not set
+      }
+    }
+  }
 }