本文通过代码示例说明如何通过JDBC方式连接ClickHouse进行应用开发。
操作步骤
使用Eclipse或其他IDE工具创建Maven项目并引入ClickHouse驱动依赖包。
<dependency> <groupId>org.lz4</groupId> <artifactId>lz4-java</artifactId> <version>1.8.0</version> </dependency> <dependency> <groupId>com.clickhouse</groupId> <artifactId>clickhouse-jdbc</artifactId> <version>0.4.6</version> </dependency>
编写应用程序代码。
以下代码演示了如何使用JDBC驱动连接集群和创建表以及写入数据。使用过程需修改集群连接串和端口参数。如果应用和ClickHouse实例在同一个VPC环境,请使用集群VPC地址,如果不在相同的VPC环境则需使用集群外网地址,如何获取外网地址,请参见申请和释放外网地址。
import java.sql.Connection; import java.sql.DriverManager; import java.sql.ResultSet; import java.sql.SQLException; import java.sql.Statement; import java.sql.Timestamp; import java.text.ParseException; import java.text.SimpleDateFormat; import java.util.Date; public class Main4 { private static final String DATE_FORMAT = "yyyy-MM-dd HH:mm:ss"; private static final SimpleDateFormat SIMPLE_DATE_FORMAT = new SimpleDateFormat(DATE_FORMAT); public static void main(String[] args) throws ClassNotFoundException, SQLException, InterruptedException, ParseException { String url = "your url"; //云数据库ClickHouse的VPC地址或外网地址 String username = "your username"; //云数据库ClickHouse的账号 String password = "your password"; //云数据库ClickHouse的密码 String connectionStr = "jdbc:clickhouse://" + url + ":8123"; try (Connection connection = DriverManager.getConnection(connectionStr, username, password); Statement stmt = connection.createStatement()) { { String createTableDDL = "create table test_table on cluster default " + "(id UInt32, " + "dt_str String, " + "dt_col DateTime) " + "engine=ReplicatedMergeTree('/clickhouse/tables/{database}/{table}/{shard}', '{replica}')" + "partition by toYYYYMM(dt_col)" + "order by (id)" + "primary key (id)" + "sample by (id)" + "settings index_granularity = 8192;"; stmt.execute(createTableDDL); System.out.println("create local table done."); } { String createTableDDL = "create table test_dist on cluster default " + "as default.test_table " + "engine=Distributed(default, default, test_table, rand());"; stmt.execute(createTableDDL); System.out.println("create distributed table done"); } System.out.println("write 100000 rows..."); long startTime = System.currentTimeMillis(); // Write 10 batch for (int batch = 0; batch < 10; batch++) { StringBuilder sb = new StringBuilder(); // Build one batch sb.append("insert into test_dist values(" + (batch * 10000) + ", '2020-02-19 16:00:00', '2020-02-19 16:00:00')"); for (int row = 1; row < 10000; row++) { sb.append(", (" + (batch * 10000 + row) + ", '2020-02-19 16:00:00', '2020-02-19 16:00:00')"); } // Write one batch: 10000 rows stmt.execute(sb.toString()); } long endTime = System.currentTimeMillis(); System.out.println("total time cost to write 10W rows: " + (endTime - startTime) + "ms"); Thread.sleep(2 * 1000); System.out.println("Select count(id)..."); try (ResultSet rs = stmt.executeQuery("select count(id) from test_dist");) { while (rs.next()) { int count = rs.getInt(1); System.out.println("id count: " + count); } } try (ResultSet rs = stmt.executeQuery("select id, dt_str, dt_col from test_dist limit 10");) { while (rs.next()) { int id = rs.getInt(1); String dateStr = rs.getString(2); Timestamp time = rs.getTimestamp(3); String defaultDate = SIMPLE_DATE_FORMAT.format(new Date(time.getTime())); System.out.println("id: " + id + ", date_str:" + dateStr + ", date_col:" + defaultDate); } } } } }
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