[TD-2271]feature: support Connection and Statement count statistics in JMX

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

-/***************************************************************************
- * Copyright (c) 2019 TAOS Data, Inc. <jhtao@taosdata.com>
- *
- * This program is free software: you can use, redistribute, and/or modify
- * it under the terms of the GNU Affero General Public License, version 3
- * or later ("AGPL"), as published by the Free Software Foundation.
- *
- * This program is distributed in the hope that it will be useful, but WITHOUT
- * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
- * FITNESS FOR A PARTICULAR PURPOSE.
- *
- * You should have received a copy of the GNU Affero General Public License
- * along with this program. If not, see <http://www.gnu.org/licenses/>.
- *****************************************************************************/
 package com.taosdata.jdbc;
 
 import java.sql.*;
 import java.util.ArrayList;
 import java.util.List;
 
-public abstract class AbstractDatabaseMetaData implements DatabaseMetaData {
+public abstract class AbstractDatabaseMetaData implements DatabaseMetaData, Wrapper {
 
     private final static String PRODUCT_NAME = "TDengine";
     private final static String PRODUCT_VESION = "2.0.x.x";
-    private final static String DRIVER_NAME = "taos-jdbcdriver";
     private final static String DRIVER_VERSION = "2.0.x";
     private final static int DRIVER_MAJAR_VERSION = 2;
     private final static int DRIVER_MINOR_VERSION = 0;
@@ -67,9 +52,7 @@ public abstract class AbstractDatabaseMetaData implements DatabaseMetaData {
         return PRODUCT_VESION;
     }
 
-    public String getDriverName() throws SQLException {
-        return DRIVER_NAME;
-    }
+    public abstract String getDriverName() throws SQLException;
 
     public String getDriverVersion() throws SQLException {
         return DRIVER_VERSION;
@@ -92,6 +75,7 @@ public abstract class AbstractDatabaseMetaData implements DatabaseMetaData {
     }
 
     public boolean supportsMixedCaseIdentifiers() throws SQLException {
+        //像database、table这些对象的标识符，在存储时是否采用大小写混合的模式
         return false;
     }
 
@@ -168,10 +152,12 @@ public abstract class AbstractDatabaseMetaData implements DatabaseMetaData {
     }
 
     public boolean nullPlusNonNullIsNull() throws SQLException {
+        // null + non-null != null
         return false;
     }
 
     public boolean supportsConvert() throws SQLException {
+        // 是否支持转换函数convert
         return false;
     }
 
@@ -468,7 +454,7 @@ public abstract class AbstractDatabaseMetaData implements DatabaseMetaData {
     }
 
     public int getDefaultTransactionIsolation() throws SQLException {
-        return 0;
+        return Connection.TRANSACTION_NONE;
     }
 
     public boolean supportsTransactions() throws SQLException {
@@ -476,6 +462,8 @@ public abstract class AbstractDatabaseMetaData implements DatabaseMetaData {
     }
 
     public boolean supportsTransactionIsolationLevel(int level) throws SQLException {
+        if (level == Connection.TRANSACTION_NONE)
+            return true;
         return false;
     }
 
@@ -516,27 +504,26 @@ public abstract class AbstractDatabaseMetaData implements DatabaseMetaData {
 
     public ResultSet getTableTypes() throws SQLException {
         DatabaseMetaDataResultSet resultSet = new DatabaseMetaDataResultSet();
-
         // set up ColumnMetaDataList
-        List<ColumnMetaData> columnMetaDataList = new ArrayList<ColumnMetaData>(1);
+        List<ColumnMetaData> columnMetaDataList = new ArrayList<>();
         ColumnMetaData colMetaData = new ColumnMetaData();
         colMetaData.setColIndex(0);
         colMetaData.setColName("TABLE_TYPE");
         colMetaData.setColSize(10);
-        colMetaData.setColType(TSDBConstants.TSDB_DATA_TYPE_BINARY);
+        colMetaData.setColType(TSDBConstants.TSDB_DATA_TYPE_NCHAR);
         columnMetaDataList.add(colMetaData);
+        resultSet.setColumnMetaDataList(columnMetaDataList);
 
         // set up rowDataList
-        List<TSDBResultSetRowData> rowDataList = new ArrayList<TSDBResultSetRowData>(2);
-        TSDBResultSetRowData rowData = new TSDBResultSetRowData();
+        List<TSDBResultSetRowData> rowDataList = new ArrayList<>();
+        TSDBResultSetRowData rowData = new TSDBResultSetRowData(1);
         rowData.setString(0, "TABLE");
         rowDataList.add(rowData);
-        rowData = new TSDBResultSetRowData();
+        rowData = new TSDBResultSetRowData(1);
         rowData.setString(0, "STABLE");
         rowDataList.add(rowData);
-
-        resultSet.setColumnMetaDataList(columnMetaDataList);
         resultSet.setRowDataList(rowDataList);
+
         return resultSet;
     }
 
@@ -615,9 +602,7 @@ public abstract class AbstractDatabaseMetaData implements DatabaseMetaData {
         return getEmptyResultSet();
     }
 
-    public ResultSet getPrimaryKeys(String catalog, String schema, String table) throws SQLException {
-        return getEmptyResultSet();
-    }
+    public abstract ResultSet getPrimaryKeys(String catalog, String schema, String table) throws SQLException;
 
     public ResultSet getImportedKeys(String catalog, String schema, String table) throws SQLException {
         return getEmptyResultSet();
@@ -718,9 +703,7 @@ public abstract class AbstractDatabaseMetaData implements DatabaseMetaData {
         return getEmptyResultSet();
     }
 
-    public ResultSet getSuperTables(String catalog, String schemaPattern, String tableNamePattern) throws SQLException {
-        return getEmptyResultSet();
-    }
+    public abstract ResultSet getSuperTables(String catalog, String schemaPattern, String tableNamePattern) throws SQLException;
 
     public ResultSet getAttributes(String catalog, String schemaPattern, String typeNamePattern,
                                    String attributeNamePattern) throws SQLException {
@@ -728,15 +711,17 @@ public abstract class AbstractDatabaseMetaData implements DatabaseMetaData {
     }
 
     public boolean supportsResultSetHoldability(int holdability) throws SQLException {
+        if (holdability == ResultSet.HOLD_CURSORS_OVER_COMMIT)
+            return true;
         return false;
     }
 
     public int getResultSetHoldability() throws SQLException {
-        return 0;
+        return ResultSet.HOLD_CURSORS_OVER_COMMIT;
     }
 
     public int getDatabaseMajorVersion() throws SQLException {
-        return 0;
+        return 2;
     }
 
     public int getDatabaseMinorVersion() throws SQLException {
@@ -744,7 +729,7 @@ public abstract class AbstractDatabaseMetaData implements DatabaseMetaData {
     }
 
     public int getJDBCMajorVersion() throws SQLException {
-        return 0;
+        return 2;
     }
 
     public int getJDBCMinorVersion() throws SQLException {
@@ -805,4 +790,18 @@ public abstract class AbstractDatabaseMetaData implements DatabaseMetaData {
     private ResultSet getEmptyResultSet() {
         return new EmptyResultSet();
     }
+
+    @Override
+    public <T> T unwrap(Class<T> iface) throws SQLException {
+        try {
+            return iface.cast(this);
+        } catch (ClassCastException cce) {
+            throw new SQLException("Unable to unwrap to " + iface.toString());
+        }
+    }
+
+    @Override
+    public boolean isWrapperFor(Class<?> iface) throws SQLException {
+        return iface.isInstance(this);
+    }
 }
\ No newline at end of file

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

-/***************************************************************************
- * Copyright (c) 2019 TAOS Data, Inc. <jhtao@taosdata.com>
- *
- * This program is free software: you can use, redistribute, and/or modify
- * it under the terms of the GNU Affero General Public License, version 3
- * or later ("AGPL"), as published by the Free Software Foundation.
- *
- * This program is distributed in the hope that it will be useful, but WITHOUT
- * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
- * FITNESS FOR A PARTICULAR PURPOSE.
- *
- * You should have received a copy of the GNU Affero General Public License
- * along with this program. If not, see <http://www.gnu.org/licenses/>.
- *****************************************************************************/
-package com.taosdata.jdbc;
-
-import java.sql.ResultSet;
-import java.sql.SQLException;
-
-/*
- * TDengine only supports a subset of the standard SQL, thus this implemetation of the
- * standard JDBC API contains more or less some adjustments customized for certain
- * compatibility needs.
- */
-public class CatalogResultSet extends TSDBResultSetWrapper {
-
-    public CatalogResultSet(ResultSet resultSet) {
-        super.setOriginalResultSet(resultSet);
-    }
-
-    @Override
-    public String getString(int columnIndex) throws SQLException {
-        if (columnIndex <= 1) {
-            return super.getString(columnIndex);
-        } else {
-            return null;
-        }
-    }
-
-    @Override
-    public boolean getBoolean(int columnIndex) throws SQLException {
-        if (columnIndex <= 1) {
-            return super.getBoolean(columnIndex);
-        } else {
-            return false;
-        }
-    }
-
-    @Override
-    public byte[] getBytes(int columnIndex) throws SQLException {
-        if (columnIndex <= 1) {
-            return super.getBytes(columnIndex);
-        } else {
-            return null;
-        }
-    }
-
-    @Override
-    public Object getObject(int columnIndex) throws SQLException {
-        if (columnIndex <= 1) {
-            return super.getObject(columnIndex);
-        } else {
-            return null;
-        }
-    }
-
-}

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

-/***************************************************************************
- * Copyright (c) 2019 TAOS Data, Inc. <jhtao@taosdata.com>
- *
- * This program is free software: you can use, redistribute, and/or modify
- * it under the terms of the GNU Affero General Public License, version 3
- * or later ("AGPL"), as published by the Free Software Foundation.
- *
- * This program is distributed in the hope that it will be useful, but WITHOUT
- * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
- * FITNESS FOR A PARTICULAR PURPOSE.
- *
- * You should have received a copy of the GNU Affero General Public License
- * along with this program. If not, see <http://www.gnu.org/licenses/>.
- *****************************************************************************/
-package com.taosdata.jdbc;
-
-import java.sql.ResultSet;
-import java.sql.SQLException;
-
-/*
- * TDengine only supports a subset of the standard SQL, thus this implemetation of the
- * standard JDBC API contains more or less some adjustments customized for certain
- * compatibility needs.
- */
-public class GetTablesResultSet extends TSDBResultSetWrapper {
-
-    private String catalog;
-    private String schemaPattern;
-    private String tableNamePattern;
-    private String[] types;
-
-    public GetTablesResultSet(ResultSet resultSet, String catalog, String schemaPattern, String tableNamePattern, String[] types) {
-        super.setOriginalResultSet(resultSet);
-        this.catalog = catalog;
-        this.schemaPattern = schemaPattern;
-        this.tableNamePattern = tableNamePattern;
-        this.types = types;
-    }
-
-    @Override
-    public String getString(int columnIndex) throws SQLException {
-        String ret = null;
-        switch (columnIndex) {
-            case 3:
-                return super.getString(1);
-            case 4:
-                return "table";
-            default:
-                return null;
-        }
-    }
-
-}