--- toc_max_heading_level: 4 sidebar_position: 2 sidebar_label: Java title: TDengine Java Connector --- import Tabs from '@theme/Tabs'; import TabItem from '@theme/TabItem'; 'taos-jdbcdriver' is TDengine's official Java language connector, which allows Java developers to develop applications that access the TDengine database. 'taos-jdbcdriver' implements the interface of the JDBC driver standard. 'taos-jdbcdriver' connect to a TDengine instance through the REST API. ## TDengine DataType vs. Java DataType TDengine currently supports timestamp, number, character, Boolean type, and the corresponding type conversion with Java is as follows: | TDengine DataType | JDBCType (driver version < 2.0.24) | JDBCType (driver version > = 2.0.24) | | ----------------- | ---------------------------------- | ------------------------------------ | | TIMESTAMP | java.lang.Long | java.sql.Timestamp | | INT | java.lang.Integer | java.lang.Integer | | BIGINT | java.lang.Long | java.lang.Long | | FLOAT | java.lang.Float | java.lang.Float | | DOUBLE | java.lang.Double | java.lang.Double | | SMALLINT | java.lang.Short | java.lang.Short | | TINYINT | java.lang.Byte | java.lang.Byte | | BOOL | java.lang.Boolean | java.lang.Boolean | | BINARY | java.lang.String | byte array | | NCHAR | java.lang.String | java.lang.String | | JSON | - | java.lang.String | **Note**: Only TAG supports JSON types ## Installation steps ### Pre-installation preparation Java 1.8 or above runtime environment and Maven 3.6 or above installed ### Install the connectors - [sonatype](https://search.maven.org/artifact/com.taosdata.jdbc/taos-jdbcdriver) - [mvnrepository](https://mvnrepository.com/artifact/com.taosdata.jdbc/taos-jdbcdriver) - [maven.aliyun](https://maven.aliyun.com/mvn/search) Add following dependency in the `pom.xml` file of your Maven project: ```xml com.taosdata.jdbc taos-jdbcdriver 2.0.** ``` You can build Java connector from source code after cloning the TDengine project: ``` git clone https://github.com/taosdata/taos-connector-jdbc.git cd taos-connector-jdbc mvn clean install -Dmaven.test.skip=true ``` After compilation, a jar package named taos-jdbcdriver-2.0.XX-dist.jar is generated in the target directory, and the compiled jar file is automatically placed in the local Maven repository. ## Establish Connection using URL TDengine's JDBC URL specification format is: `jdbc:[TAOS-RS]://[host_name]:[port]/[database_name]?batchfetch={true|false}&useSSL={true|false}&token={token}&httpPoolSize={httpPoolSize}&httpKeepAlive={true|false}]&httpConnectTimeout={httpTimeout}&httpSocketTimeout={socketTimeout}` ```java Class.forName("com.taosdata.jdbc.rs.RestfulDriver"); String jdbcUrl = System.getenv("TDENGINE_JDBC_URL"); Connection conn = DriverManager.getConnection(jdbcUrl); ``` Note: - REST API is stateless. When using the JDBC REST connection, you need to specify the database name of the table and super table in SQL. For example. ```sql INSERT INTO test.t1 USING test.weather (ts, temperature) TAGS('California.SanFrancisco') VALUES(now, 24.6); ``` - If dbname is specified in the URL, JDBC REST connections will use `/rest/sql/dbname` as the URL for REST requests by default, and there is no need to specify dbname in SQL. For example, if the URL is `jdbc:TAOS-RS://127.0.0.1:6041/test`, then the SQL can be executed: ```sql insert into test using weather(ts, temperature) tags('California.SanFrancisco') values(now, 24.6); ``` ### Establish Connection using URL and Properties In addition to getting the connection from the specified URL, you can use Properties to specify parameters when the connection is established. ```java public Connection getRestConn() throws Exception{ Class.forName("com.taosdata.jdbc.rs.RestfulDriver"); String jdbcUrl = System.getenv("TDENGINE_JDBC_URL"); Properties connProps = new Properties(); connProps.setProperty(TSDBDriver.PROPERTY_KEY_BATCH_LOAD, "true"); Connection conn = DriverManager.getConnection(jdbcUrl, connProps); return conn; } ``` ### Priority of configuration parameters If the configuration parameters are duplicated in the URL, Properties, the `priority` of the parameters, from highest to lowest, are as follows: 1. JDBC URL parameters, as described above, can be specified in the parameters of the JDBC URL. 2. Properties connProps ## Usage Examples ### Create Database and Tables ```java Statement stmt = conn.createStatement(); // create database stmt.executeUpdate("create database if not exists db"); // create table stmt.executeUpdate("create table if not exists db.tb (ts timestamp, temperature int, humidity float)"); ``` ### Insert Data ```java // insert data int affectedRows = stmt.executeUpdate("insert into tb values(now, 23, 10.3) (now + 1s, 20, 9.3)"); System.out.println("insert " + affectedRows + " rows."); ``` `now`` is an internal function. The default is the current time of the client's computer. ### Querying data ```java // query data ResultSet resultSet = stmt.executeQuery("select * from tb"); Timestamp ts = null; int temperature = 0; float humidity = 0; while(resultSet.next()){ ts = resultSet.getTimestamp(1); temperature = resultSet.getInt(2); humidity = resultSet.getFloat("humidity"); System.out.printf("%s, %d, %s\n", ts, temperature, humidity); } ``` The query is consistent with operating a relational database. When using subscripts to get the contents of the returned fields, you have to start from 1. However, we recommend using the field names to get the values of the fields in the result set. ### Handling Exceptions After an error is reported, the error message and error code can be obtained through SQLException. ```java try (Statement statement = connection.createStatement()) { // executeQuery ResultSet resultSet = statement.executeQuery(sql); // print result printResult(resultSet); } catch (SQLException e) { System.out.println("ERROR Message: " + e.getMessage()); System.out.println("ERROR Code: " + e.getErrorCode()); e.printStackTrace(); } ``` There are three types of error codes that the JDBC connector can report: - Error code of the JDBC driver itself (error code between 0x2301 and 0x2350) - Error code of the native connection method (error code between 0x2351 and 0x2400) - Error code of other TDengine function modules ### Closing resources ```java resultSet.close(); stmt.close(); conn.close(); ``` :::note Be sure to close the connection, otherwise, there will be a connection leak. ::: ### Use with Connection Pool #### HikariCP Example usage is as follows. ```java public static void main(String[] args) throws SQLException { HikariConfig config = new HikariConfig(); // jdbc properties config.setJdbcUrl("jdbc:TAOS://127.0.0.1:6030/log"); config.setUsername("root"); config.setPassword("taosdata"); // connection pool configurations config.setMinimumIdle(10); //minimum number of idle connection config.setMaximumPoolSize(10); //maximum number of connection in the pool config.setConnectionTimeout(30000); //maximum wait milliseconds for get connection from pool config.setMaxLifetime(0); // maximum life time for each connection config.setIdleTimeout(0); // max idle time for recycle idle connection config.setConnectionTestQuery("select server_status()"); //validation query HikariDataSource ds = new HikariDataSource(config); //create datasource Connection connection = ds.getConnection(); // get connection Statement statement = connection.createStatement(); // get statement //query or insert // ... connection.close(); // put back to connection pool } ``` > getConnection(), you need to call the close() method after you finish using it. It doesn't close the connection. It just puts it back into the connection pool. > For more questions about using HikariCP, please see the [official instructions](https://github.com/brettwooldridge/HikariCP). #### Druid Example usage is as follows. ```java public static void main(String[] args) throws Exception { DruidDataSource dataSource = new DruidDataSource(); // jdbc properties dataSource.setDriverClassName("com.taosdata.jdbc.TSDBDriver"); dataSource.setUrl(url); dataSource.setUsername("root"); dataSource.setPassword("taosdata"); // pool configurations dataSource.setInitialSize(10); dataSource.setMinIdle(10); dataSource.setMaxActive(10); dataSource.setMaxWait(30000); dataSource.setValidationQuery("select server_status()"); Connection connection = dataSource.getConnection(); // get connection Statement statement = connection.createStatement(); // get statement //query or insert // ... connection.close(); // put back to connection pool } ``` For more questions about using druid, please see [Official Instructions](https://github.com/alibaba/druid). ### More sample programs The source code of the sample application is under `TDengine/examples/JDBC`: - JDBCDemo: JDBC sample source code. - JDBCConnectorChecker: JDBC installation checker source and jar package. - connectionPools: using taos-jdbcdriver in connection pools such as HikariCP, Druid, dbcp, c3p0, etc. - SpringJdbcTemplate: using taos-jdbcdriver in Spring JdbcTemplate. - mybatisplus-demo: using taos-jdbcdriver in Springboot + Mybatis. Please refer to: [JDBC example](https://github.com/taosdata/TDengine/tree/develop/examples/JDBC) ## Recent update logs | taos-jdbcdriver version | major changes | | :---------------------: | :------------------------------------------: | | 2.0.38 | JDBC REST connections add bulk pull function | | 2.0.37 | Added support for json tags | | 2.0.36 | Add support for schemaless writing | ## API Reference [taos-jdbcdriver doc](https://docs.taosdata.com/api/taos-jdbcdriver)