Fix issue #270

src/connector/jdbc/pom.xml

@@ -3,7 +3,7 @@
 	<modelVersion>4.0.0</modelVersion>
 	<groupId>com.taosdata.jdbc</groupId>
 	<artifactId>taos-jdbcdriver</artifactId>
-	<version>1.0.0</version>
+	<version>1.0.1</version>
 	<name>JDBCDriver</name>
 	<description>TDengine JDBC Driver</description>
 	<properties>  

src/connector/jdbc/src/main/java/com/taosdata/jdbc/TSDBConstants.java

@@ -24,6 +24,8 @@ public abstract class TSDBConstants {
 	public static final String INVALID_VARIABLES = "invalid variables";
 	public static Map<Integer, String> DATATYPE_MAP = null;
 
+	public static final long JNI_NULL_POINTER = 0L;
+
 	public static final int JNI_SUCCESS = 0;
 	public static final int JNI_TDENGINE_ERROR = -1;
 	public static final int JNI_CONNECTION_NULL = -2;

src/connector/jdbc/src/main/java/com/taosdata/jdbc/TSDBJNIConnector.java

@@ -19,7 +19,6 @@ import java.sql.SQLWarning;
 import java.util.List;
 
 public class TSDBJNIConnector {
-	static final long INVALID_CONNECTION_POINTER_VALUE = 0l;
 	static volatile Boolean isInitialized = false;
 
 	static {
@@ -29,7 +28,12 @@ public class TSDBJNIConnector {
 	/**
 	 * Connection pointer used in C
 	 */
-	private long taos = INVALID_CONNECTION_POINTER_VALUE;
+	private long taos = TSDBConstants.JNI_NULL_POINTER;
+
+	/**
+	 * Result set pointer for the current connection
+	 */
+	private long taosResultSetPointer = TSDBConstants.JNI_NULL_POINTER;
 
 	/**
 	 * result set status in current connection
@@ -41,7 +45,7 @@ public class TSDBJNIConnector {
 	 * Whether the connection is closed
 	 */
 	public boolean isClosed() {
-		return this.taos == INVALID_CONNECTION_POINTER_VALUE;
+		return this.taos == TSDBConstants.JNI_NULL_POINTER;
 	}
 
 	/**
@@ -86,13 +90,13 @@ public class TSDBJNIConnector {
 	 * @throws SQLException
 	 */
 	public boolean connect(String host, int port, String dbName, String user, String password) throws SQLException {
-		if (this.taos != INVALID_CONNECTION_POINTER_VALUE) {
+		if (this.taos != TSDBConstants.JNI_NULL_POINTER) {
 			this.closeConnectionImp(this.taos);
-			this.taos = INVALID_CONNECTION_POINTER_VALUE;
+			this.taos = TSDBConstants.JNI_NULL_POINTER;
 		}
 
 		this.taos = this.connectImp(host, port, dbName, user, password);
-		if (this.taos == INVALID_CONNECTION_POINTER_VALUE) {
+		if (this.taos == TSDBConstants.JNI_NULL_POINTER) {
 			throw new SQLException(TSDBConstants.WrapErrMsg(this.getErrMsg()), "", this.getErrCode());
 		}
 
@@ -108,13 +112,7 @@ public class TSDBJNIConnector {
 	 */
 	public int executeQuery(String sql) throws SQLException {
         if (!this.isResultsetClosed) {
-            //throw new RuntimeException(TSDBConstants.WrapErrMsg("Connection already has an open result set"));
-        	long resultSetPointer = this.getResultSet();
-        	if (resultSetPointer == TSDBConstants.JNI_CONNECTION_NULL) {
-        		//do nothing
-        	} else {
-        		this.freeResultSet(resultSetPointer);
-        	}
+        	freeResultSet(taosResultSetPointer);
         }
         
         int code;
@@ -134,6 +132,13 @@ public class TSDBJNIConnector {
             }
         }
 
+        // Try retrieving result set for the executed SQLusing the current connection pointer. If the executed
+        // SQL is a DML/DDL which doesn't return a result set, then taosResultSetPointer should be 0L. Otherwise,
+        // taosResultSetPointer should be a non-zero value.
+        taosResultSetPointer = this.getResultSetImp(this.taos);
+        if (taosResultSetPointer != TSDBConstants.JNI_NULL_POINTER) {
+            isResultsetClosed = false;
+        }
         return code;
 	}
 
@@ -162,8 +167,7 @@ public class TSDBJNIConnector {
      * Each connection should have a single open result set at a time
 	 */
 	public long getResultSet() {
-		long res = this.getResultSetImp(this.taos);
-        return res;
+        return taosResultSetPointer;
 	}
 
 	private native long getResultSetImp(long connection);
@@ -172,11 +176,31 @@ public class TSDBJNIConnector {
 	 * Free resultset operation from C to release resultset pointer by JNI
 	 */
 	public int freeResultSet(long result) {
-		int res = this.freeResultSetImp(this.taos, result);
-		this.isResultsetClosed = true; // reset resultSetPointer to 0 after freeResultSetImp() return
+        int res = TSDBConstants.JNI_SUCCESS;
+        if (result != taosResultSetPointer && taosResultSetPointer != TSDBConstants.JNI_NULL_POINTER) {
+            throw new RuntimeException("Invalid result set pointer");
+        } else if (taosResultSetPointer != TSDBConstants.JNI_NULL_POINTER){
+            res = this.freeResultSetImp(this.taos, result);
+            isResultsetClosed = true; // reset resultSetPointer to 0 after freeResultSetImp() return
+            taosResultSetPointer = TSDBConstants.JNI_NULL_POINTER;
+        }
         return res;
 	}
 
+    /**
+     * Close the open result set which is associated to the current connection. If the result set is already
+     * closed, return 0 for success.
+     * @return
+     */
+	public int freeResultSet() {
+	    int resCode = TSDBConstants.JNI_SUCCESS;
+        if (!isResultsetClosed) {
+            resCode = this.freeResultSetImp(this.taos, this.taosResultSetPointer);
+            taosResultSetPointer = TSDBConstants.JNI_NULL_POINTER;
+        }
+        return resCode;
+    }
+
 	private native int freeResultSetImp(long connection, long result);
 
 	/**
@@ -220,7 +244,7 @@ public class TSDBJNIConnector {
 		if (code < 0) {
 			throw new SQLException(TSDBConstants.FixErrMsg(code), "", this.getErrCode());
 		} else if (code == 0){
-			this.taos = INVALID_CONNECTION_POINTER_VALUE;
+			this.taos = TSDBConstants.JNI_NULL_POINTER;
 		} else {
 		    throw new SQLException("Undefined error code returned by TDengine when closing a connection");
         }

src/connector/jdbc/src/main/java/com/taosdata/jdbc/TSDBPreparedStatement.java

@@ -244,7 +244,7 @@ public class TSDBPreparedStatement extends TSDBStatement implements PreparedStat
 
 	@Override
 	public boolean execute() throws SQLException {
-		return executeUpdate(getNativeSql()) == 0;
+	    return super.execute(getNativeSql());
 	}
 
 	@Override

src/connector/jdbc/src/main/java/com/taosdata/jdbc/TSDBStatement.java

@@ -27,8 +27,14 @@ public class TSDBStatement implements Statement {
 	/** Timeout for a query */
 	protected int queryTimeout = 0;
 
+    /**
+     * Status of current statement
+     */
+	private boolean isClosed = true;
+
 	TSDBStatement(TSDBJNIConnector connecter) {
 		this.connecter = connecter;
+		this.isClosed = false;
 	}
 
 	public <T> T unwrap(Class<T> iface) throws SQLException {
@@ -40,13 +46,16 @@ public class TSDBStatement implements Statement {
 	}
 
 	public ResultSet executeQuery(String sql) throws SQLException {
+        if (isClosed) {
+            throw new SQLException("Invalid method call on a closed statement.");
+        }
 		this.connecter.executeQuery(sql);
 
 		long resultSetPointer = this.connecter.getResultSet();
 
 		if (resultSetPointer == TSDBConstants.JNI_CONNECTION_NULL) {
 			throw new SQLException(TSDBConstants.FixErrMsg(TSDBConstants.JNI_CONNECTION_NULL));
-		} else if (resultSetPointer == 0) {
+		} else if (resultSetPointer == TSDBConstants.JNI_NULL_POINTER) {
 			return null;
 		} else {
 			return new TSDBResultSet(this.connecter, resultSetPointer);
@@ -54,7 +63,20 @@ public class TSDBStatement implements Statement {
 	}
 
 	public int executeUpdate(String sql) throws SQLException {
-		return this.connecter.executeQuery(sql);
+        if (isClosed) {
+            throw new SQLException("Invalid method call on a closed statement.");
+        }
+		int res = this.connecter.executeQuery(sql);
+		long resultSetPointer = this.connecter.getResultSet();
+
+		if (resultSetPointer == TSDBConstants.JNI_CONNECTION_NULL) {
+			throw new SQLException(TSDBConstants.FixErrMsg(TSDBConstants.JNI_CONNECTION_NULL));
+		} else if (resultSetPointer != TSDBConstants.JNI_NULL_POINTER) {
+			this.connecter.freeResultSet();
+			throw new SQLException("The executed SQL is not a DML or a DDL");
+		} else {
+			return res;
+		}
 	}
 
 	public String getErrorMsg() {
@@ -62,6 +84,12 @@ public class TSDBStatement implements Statement {
 	}
 
 	public void close() throws SQLException {
+        if (!isClosed) {
+            if (!this.connecter.isResultsetClosed()) {
+                this.connecter.freeResultSet();
+            }
+            isClosed = true;
+        }
 	}
 
 	public int getMaxFieldSize() throws SQLException {
@@ -110,19 +138,38 @@ public class TSDBStatement implements Statement {
 	}
 
 	public boolean execute(String sql) throws SQLException {
-		return executeUpdate(sql) == 0;
+        if (isClosed) {
+            throw new SQLException("Invalid method call on a closed statement.");
+        }
+	    boolean res = true;
+	    this.connecter.executeQuery(sql);
+	    long resultSetPointer = this.connecter.getResultSet();
+
+        if (resultSetPointer == TSDBConstants.JNI_CONNECTION_NULL) {
+            throw new SQLException(TSDBConstants.FixErrMsg(TSDBConstants.JNI_CONNECTION_NULL));
+        } else if (resultSetPointer == TSDBConstants.JNI_NULL_POINTER) {
+            // no result set is retrieved
+            res = false;
+        }
+        return res;
 	}
 
 	public ResultSet getResultSet() throws SQLException {
+        if (isClosed) {
+            throw new SQLException("Invalid method call on a closed statement.");
+        }
 		long resultSetPointer = connecter.getResultSet();
 		TSDBResultSet resSet = null;
-        if (resultSetPointer != 0l) {
+        if (resultSetPointer != TSDBConstants.JNI_NULL_POINTER) {
             resSet = new TSDBResultSet(connecter, resultSetPointer);
         }
 		return resSet;
 	}
 
 	public int getUpdateCount() throws SQLException {
+        if (isClosed) {
+            throw new SQLException("Invalid method call on a closed statement.");
+        }
 		return this.connecter.getAffectedRows();
 	}
 
@@ -171,6 +218,9 @@ public class TSDBStatement implements Statement {
 	}
 
 	public int[] executeBatch() throws SQLException {
+        if (isClosed) {
+            throw new SQLException("Invalid method call on a closed statement.");
+        }
 		if (batchedArgs == null) {
 			throw new SQLException(TSDBConstants.WrapErrMsg("Batch is empty!"));
 		} else {
@@ -223,7 +273,7 @@ public class TSDBStatement implements Statement {
 	}
 
 	public boolean isClosed() throws SQLException {
-		throw new SQLException(TSDBConstants.UNSUPPORT_METHOD_EXCEPTIONZ_MSG);
+	    return isClosed;
 	}
 
 	public void setPoolable(boolean poolable) throws SQLException {

tests/examples/JDBC/JDBCDemo/pom.xml

@@ -63,7 +63,7 @@
         <dependency>
             <groupId>com.taosdata.jdbc</groupId>
             <artifactId>taos-jdbcdriver</artifactId>
-            <version>1.0.0</version>
+            <version>1.0.1</version>
         </dependency>
     </dependencies>
 </project>