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docs: add tmq sample (#16080)

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huolibo 2022-08-13 00:39:10 +08:00 committed by GitHub
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6 changed files with 129 additions and 45 deletions
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2
docs/en/07-develop/_sub_java.mdx
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@ -1,5 +1,7 @@
```java
{{#include docs/examples/java/src/main/java/com/taos/example/SubscribeDemo.java}}
{{#include docs/examples/java/src/main/java/com/taos/example/MetersDeserializer.java}}
{{#include docs/examples/java/src/main/java/com/taos/example/Meters.java}}
```
:::note
For now Java connector doesn't provide asynchronous subscription, but `TimerTask` can be used to achieve similar purpose.

2
docs/examples/java/pom.xml
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@ -21,7 +21,7 @@
<dependency>
<groupId>com.taosdata.jdbc</groupId>
<artifactId>taos-jdbcdriver</artifactId>
<version>2.0.38</version>
<version>3.0.0</version>
</dependency>
<!-- ANCHOR_END: dep-->
<dependency>

62
docs/examples/java/src/main/java/com/taos/example/Meters.java Normal file
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@ -0,0 +1,62 @@
package com.taos.example;
import java.sql.Timestamp;
public class Meters {
private Timestamp ts;
private float current;
private int voltage;
private int groupid;
private String location;
public Timestamp getTs() {
return ts;
}
public void setTs(Timestamp ts) {
this.ts = ts;
}
public float getCurrent() {
return current;
}
public void setCurrent(float current) {
this.current = current;
}
public int getVoltage() {
return voltage;
}
public void setVoltage(int voltage) {
this.voltage = voltage;
}
public int getGroupid() {
return groupid;
}
public void setGroupid(int groupid) {
this.groupid = groupid;
}
public String getLocation() {
return location;
}
public void setLocation(String location) {
this.location = location;
}
@Override
public String toString() {
return "Meters{" +
"ts=" + ts +
", current=" + current +
", voltage=" + voltage +
", groupid=" + groupid +
", location='" + location + '\'' +
'}';
}
}

6
docs/examples/java/src/main/java/com/taos/example/MetersDeserializer.java Normal file
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@ -0,0 +1,6 @@
package com.taos.example;
import com.taosdata.jdbc.tmq.ReferenceDeserializer;
public class MetersDeserializer extends ReferenceDeserializer<Meters> {
}

100
docs/examples/java/src/main/java/com/taos/example/SubscribeDemo.java
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@ -1,65 +1,77 @@
package com.taos.example;
import com.taosdata.jdbc.TSDBConnection;
import com.taosdata.jdbc.TSDBDriver;
import com.taosdata.jdbc.TSDBResultSet;
import com.taosdata.jdbc.TSDBSubscribe;
import com.taosdata.jdbc.tmq.ConsumerRecords;
import com.taosdata.jdbc.tmq.TMQConstants;
import com.taosdata.jdbc.tmq.TaosConsumer;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.sql.Statement;
import java.time.Duration;
import java.util.Collections;
import java.util.Properties;
import java.util.concurrent.TimeUnit;
import java.util.Timer;
import java.util.TimerTask;
import java.util.concurrent.atomic.AtomicBoolean;
public class SubscribeDemo {
private static final String topic = "topic-meter-current-bg-10";
private static final String sql = "select * from meters where current > 10";
private static final String TOPIC = "tmq_topic";
private static final String DB_NAME = "meters";
private static final AtomicBoolean shutdown = new AtomicBoolean(false);
public static void main(String[] args) {
Connection connection = null;
TSDBSubscribe subscribe = null;
Timer timer = new Timer();
timer.schedule(new TimerTask() {
public void run() {
shutdown.set(true);
}
}, 3_000);
try {
// prepare
Class.forName("com.taosdata.jdbc.TSDBDriver");
String jdbcUrl = "jdbc:TAOS://127.0.0.1:6030/?user=root&password=taosdata";
Connection connection = DriverManager.getConnection(jdbcUrl);
try (Statement statement = connection.createStatement()) {
statement.executeUpdate("drop topic if exists " + TOPIC);
statement.executeUpdate("drop database if exists " + DB_NAME);
statement.executeUpdate("create database " + DB_NAME);
statement.executeUpdate("use " + DB_NAME);
statement.executeUpdate(
"CREATE TABLE `meters` (`ts` TIMESTAMP, `current` FLOAT, `voltage` INT) TAGS (`groupid` INT, `location` BINARY(16))");
statement.executeUpdate("CREATE TABLE `d0` USING `meters` TAGS(0, 'Los Angles')");
statement.executeUpdate("INSERT INTO `d0` values(now - 10s, 0.32, 116)");
statement.executeUpdate("INSERT INTO `d0` values(now - 8s, NULL, NULL)");
statement.executeUpdate(
"INSERT INTO `d1` USING `meters` TAGS(1, 'San Francisco') values(now - 9s, 10.1, 119)");
statement.executeUpdate(
"INSERT INTO `d1` values (now-8s, 10, 120) (now - 6s, 10, 119) (now - 4s, 11.2, 118)");
// create topic
statement.executeUpdate("create topic " + TOPIC + " as select * from meters");
}
// create consumer
Properties properties = new Properties();
properties.setProperty(TSDBDriver.PROPERTY_KEY_CHARSET, "UTF-8");
properties.setProperty(TSDBDriver.PROPERTY_KEY_TIME_ZONE, "UTC-8");
String jdbcUrl = "jdbc:TAOS://127.0.0.1:6030/power?user=root&password=taosdata";
connection = DriverManager.getConnection(jdbcUrl, properties);
// create subscribe
subscribe = ((TSDBConnection) connection).subscribe(topic, sql, true);
int count = 0;
while (count < 10) {
// wait 1 second to avoid frequent calls to consume
TimeUnit.SECONDS.sleep(1);
// consume
TSDBResultSet resultSet = subscribe.consume();
if (resultSet == null) {
continue;
}
ResultSetMetaData metaData = resultSet.getMetaData();
while (resultSet.next()) {
int columnCount = metaData.getColumnCount();
for (int i = 1; i <= columnCount; i++) {
System.out.print(metaData.getColumnLabel(i) + ": " + resultSet.getString(i) + "\t");
properties.setProperty(TMQConstants.BOOTSTRAP_SERVERS, "127.0.0.1:6030");
properties.setProperty(TMQConstants.MSG_WITH_TABLE_NAME, "true");
properties.setProperty(TMQConstants.ENABLE_AUTO_COMMIT, "true");
properties.setProperty(TMQConstants.GROUP_ID, "test");
properties.setProperty(TMQConstants.VALUE_DESERIALIZER,
"com.taosdata.jdbc.MetersDeserializer");
// poll data
try (TaosConsumer<Meters> consumer = new TaosConsumer<>(properties)) {
consumer.subscribe(Collections.singletonList(TOPIC));
while (!shutdown.get()) {
ConsumerRecords<Meters> meters = consumer.poll(Duration.ofMillis(100));
for (Meters meter : meters) {
System.out.println(meter);
}
System.out.println();
count++;
}
}
} catch (Exception e) {
} catch (ClassNotFoundException | SQLException e) {
e.printStackTrace();
} finally {
try {
if (null != subscribe)
// close subscribe
subscribe.close(true);
if (connection != null)
connection.close();
} catch (SQLException throwable) {
throwable.printStackTrace();
}
}
timer.cancel();
}
}

2
docs/zh/07-develop/_sub_java.mdx
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@ -1,5 +1,7 @@
```java
{{#include docs/examples/java/src/main/java/com/taos/example/SubscribeDemo.java}}
{{#include docs/examples/java/src/main/java/com/taos/example/MetersDeserializer.java}}
{{#include docs/examples/java/src/main/java/com/taos/example/Meters.java}}
```
:::note
目前 Java 接口没有提供异步订阅模式，但用户程序可以通过创建 `TimerTask` 等方式达到同样的效果。