JDBC (不推荐)
大约 3 分钟
JDBC (不推荐)
注意: 目前的JDBC实现仅是为与第三方工具连接使用的。使用JDBC(执行插入语句时)无法提供高性能写入。
对于Java应用,我们推荐使用Java 原生接口
依赖
- JDK >= 1.8
- Maven >= 3.6
安装方法
在根目录下执行下面的命令:
mvn clean install -pl iotdb-client/jdbc -am -Dmaven.test.skip=true
在 MAVEN 中使用 IoTDB JDBC
<dependencies>
<dependency>
<groupId>org.apache.iotdb</groupId>
<artifactId>iotdb-jdbc</artifactId>
<version>1.3.1</version>
</dependency>
</dependencies>
示例代码
本章提供了如何建立数据库连接、执行 SQL 和显示查询结果的示例。
要求您已经在工程中包含了数据库编程所需引入的包和 JDBC class.
注意:为了更快地插入,建议使用 executeBatch()
import java.sql.*;
import org.apache.iotdb.jdbc.IoTDBSQLException;
public class JDBCExample {
/**
* Before executing a SQL statement with a Statement object, you need to create a Statement object using the createStatement() method of the Connection object.
* After creating a Statement object, you can use its execute() method to execute a SQL statement
* Finally, remember to close the 'statement' and 'connection' objects by using their close() method
* For statements with query results, we can use the getResultSet() method of the Statement object to get the result set.
*/
public static void main(String[] args) throws SQLException {
Connection connection = getConnection();
if (connection == null) {
System.out.println("get connection defeat");
return;
}
Statement statement = connection.createStatement();
//Create database
try {
statement.execute("CREATE DATABASE root.demo");
}catch (IoTDBSQLException e){
System.out.println(e.getMessage());
}
//SHOW DATABASES
statement.execute("SHOW DATABASES");
outputResult(statement.getResultSet());
//Create time series
//Different data type has different encoding methods. Here use INT32 as an example
try {
statement.execute("CREATE TIMESERIES root.demo.s0 WITH DATATYPE=INT32,ENCODING=RLE;");
}catch (IoTDBSQLException e){
System.out.println(e.getMessage());
}
//Show time series
statement.execute("SHOW TIMESERIES root.demo");
outputResult(statement.getResultSet());
//Show devices
statement.execute("SHOW DEVICES");
outputResult(statement.getResultSet());
//Count time series
statement.execute("COUNT TIMESERIES root");
outputResult(statement.getResultSet());
//Count nodes at the given level
statement.execute("COUNT NODES root LEVEL=3");
outputResult(statement.getResultSet());
//Count timeseries group by each node at the given level
statement.execute("COUNT TIMESERIES root GROUP BY LEVEL=3");
outputResult(statement.getResultSet());
//Execute insert statements in batch
statement.addBatch("insert into root.demo(timestamp,s0) values(1,1);");
statement.addBatch("insert into root.demo(timestamp,s0) values(2,15);");
statement.addBatch("insert into root.demo(timestamp,s0) values(2,17);");
statement.addBatch("insert into root.demo(timestamp,s0) values(4,12);");
statement.executeBatch();
statement.clearBatch();
//Full query statement
String sql = "select * from root.demo";
ResultSet resultSet = statement.executeQuery(sql);
System.out.println("sql: " + sql);
outputResult(resultSet);
//Exact query statement
sql = "select s0 from root.demo where time = 4;";
resultSet= statement.executeQuery(sql);
System.out.println("sql: " + sql);
outputResult(resultSet);
//Time range query
sql = "select s0 from root.demo where time >= 2 and time < 5;";
resultSet = statement.executeQuery(sql);
System.out.println("sql: " + sql);
outputResult(resultSet);
//Aggregate query
sql = "select count(s0) from root.demo;";
resultSet = statement.executeQuery(sql);
System.out.println("sql: " + sql);
outputResult(resultSet);
//Delete time series
statement.execute("delete timeseries root.demo.s0");
//close connection
statement.close();
connection.close();
}
public static Connection getConnection() {
// JDBC driver name and database URL
String driver = "org.apache.iotdb.jdbc.IoTDBDriver";
String url = "jdbc:iotdb://127.0.0.1:6667/";
// set rpc compress mode
// String url = "jdbc:iotdb://127.0.0.1:6667?rpc_compress=true";
// Database credentials
String username = "root";
String password = "root";
Connection connection = null;
try {
Class.forName(driver);
connection = DriverManager.getConnection(url, username, password);
} catch (ClassNotFoundException e) {
e.printStackTrace();
} catch (SQLException e) {
e.printStackTrace();
}
return connection;
}
/**
* This is an example of outputting the results in the ResultSet
*/
private static void outputResult(ResultSet resultSet) throws SQLException {
if (resultSet != null) {
System.out.println("--------------------------");
final ResultSetMetaData metaData = resultSet.getMetaData();
final int columnCount = metaData.getColumnCount();
for (int i = 0; i < columnCount; i++) {
System.out.print(metaData.getColumnLabel(i + 1) + " ");
}
System.out.println();
while (resultSet.next()) {
for (int i = 1; ; i++) {
System.out.print(resultSet.getString(i));
if (i < columnCount) {
System.out.print(", ");
} else {
System.out.println();
break;
}
}
}
System.out.println("--------------------------\n");
}
}
}
可以在 url 中指定 version 参数:
String url = "jdbc:iotdb://127.0.0.1:6667?version=V_1_0";
version 表示客户端使用的 SQL 语义版本,用于升级 0.13 时兼容 0.12 的 SQL 语义,可能取值有:V_0_12
、V_0_13
、V_1_0
。