从文件中读取数据
这是最简单的数据读取方式。当需要进行功能测试时，可以将数据保存在文件中，读取后验证流处理的逻辑是否符合预期。
程序代码：
package cn.jihui.flink
import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment
object readFile {
def main(args: Array[String]): Unit = {
val env = StreamExecutionEnvironment.getExecutionEnvironment
val file_name = "C:\\Users\\32985\\IdeaProjects\\flink_demo1\\resources\\wc.txt"
val streamData = env.readTextFile(file_name)
streamData.print
env.execute("read data from file")
}
}
输出结果
"C:\Program Files\Java\jdk-11\bin\java.exe" "-javaagent:D:\Program Files\JetBrains\IntelliJ IDEA Community Edition 2019.3.3\lib\idea_rt.jar=61478:D:\Program Files\JetBrains\IntelliJ IDEA Community Edition 2019.3.3\bin" -Dfile.encoding=UTF-8 -classpath C:\Users\32985\IdeaProjects\flink_demo1\out\production\flink_demo1;D:\Bigdata\scala-2.12.18\lib\scala-library.jar;D:\Bigdata\scala-2.12.18\lib\scala-parser-combinators_2.12-1.0.7.jar;D:\Bigdata\scala-2.12.18\lib\scala-reflect.jar;D:\Bigdata\scala-2.12.18\lib\scala-swing_2.12-2.0.3.jar;D:\Bigdata\scala-2.12.18\lib\scala-xml_2.12-2.1.0.jar;D:\Bigdata\flink-1.10.1\lib\log4j-1.2.17.jar;D:\Bigdata\flink-1.10.1\lib\slf4j-log4j12-1.7.15.jar;D:\Bigdata\flink-1.10.1\lib\flink-dist_2.12-1.10.1.jar;D:\Bigdata\flink-1.10.1\lib\flink-table_2.12-1.10.1.jar;D:\Bigdata\flink-1.10.1\lib\flink-table-blink_2.12-1.10.1.jar cn.jihui.flink.readFile
log4j:WARN No appenders could be found for logger (org.apache.flink.api.java.typeutils.TypeExtractor).
log4j:WARN Please initialize the log4j system properly.
log4j:WARN See http://logging.apache.org/log4j/1.2/faq.html#noconfig for more info.
WARNING: An illegal reflective access operation has occurred
WARNING: Illegal reflective access by org.apache.flink.api.java.ClosureCleaner (file:/D:/Bigdata/flink-1.10.1/lib/flink-dist_2.12-1.10.1.jar) to field java.lang.String.value
WARNING: Please consider reporting this to the maintainers of org.apache.flink.api.java.ClosureCleaner
WARNING: Use --illegal-access=warn to enable warnings of further illegal reflective access operations
WARNING: All illegal access operations will be denied in a future release
2> hello world
3> how are you
5> I am fine
7> how old are you
Process finished with exit code 0
从Socket中读取数据
用于验证一些通过Socket传输数据的场景非常方便。
程序代码：
package cn.jihui.flink
import org.apache.flink.streaming.api.scala.StreamExecutionEnvironment
object readSocket {
def main(args: Array[String]): Unit = {
val env = StreamExecutionEnvironment.getExecutionEnvironment
val ip = "172.16.3.6"
val port = 9999
val streamData = env.socketTextStream(ip, port)
streamData.print
env.execute("read data from socket")
}
}
测试时，需要先在172.16.3.6的服务器上启动nc，然后再启动Flink读取数据。如
[bigdata@vm6 ~]$ nc -lk 9999
hello world
how are you
happy new year
在nc每输入一行数据，在Flink上均可接收到该行数据。
Flink输出内容如下：
"C:\Program Files\Java\jdk-11\bin\java.exe" "-javaagent:D:\Program Files\JetBrains\IntelliJ IDEA Community Edition 2019.3.3\lib\idea_rt.jar=61731:D:\Program Files\JetBrains\IntelliJ IDEA Community Edition 2019.3.3\bin" -Dfile.encoding=UTF-8 -classpath C:\Users\32985\IdeaProjects\flink_demo1\out\production\flink_demo1;D:\Bigdata\scala-2.12.18\lib\scala-library.jar;D:\Bigdata\scala-2.12.18\lib\scala-parser-combinators_2.12-1.0.7.jar;D:\Bigdata\scala-2.12.18\lib\scala-reflect.jar;D:\Bigdata\scala-2.12.18\lib\scala-swing_2.12-2.0.3.jar;D:\Bigdata\scala-2.12.18\lib\scala-xml_2.12-2.1.0.jar;D:\Bigdata\flink-1.10.1\lib\log4j-1.2.17.jar;D:\Bigdata\flink-1.10.1\lib\slf4j-log4j12-1.7.15.jar;D:\Bigdata\flink-1.10.1\lib\flink-dist_2.12-1.10.1.jar;D:\Bigdata\flink-1.10.1\lib\flink-table_2.12-1.10.1.jar;D:\Bigdata\flink-1.10.1\lib\flink-table-blink_2.12-1.10.1.jar cn.jihui.flink.readSocket
log4j:WARN No appenders could be found for logger (org.apache.flink.api.java.ClosureCleaner).
log4j:WARN Please initialize the log4j system properly.
log4j:WARN See http://logging.apache.org/log4j/1.2/faq.html#noconfig for more info.
WARNING: An illegal reflective access operation has occurred
WARNING: Illegal reflective access by org.apache.flink.api.java.ClosureCleaner (file:/D:/Bigdata/flink-1.10.1/lib/flink-dist_2.12-1.10.1.jar) to field java.lang.String.value
WARNING: Please consider reporting this to the maintainers of org.apache.flink.api.java.ClosureCleaner
WARNING: Use --illegal-access=warn to enable warnings of further illegal reflective access operations
WARNING: All illegal access operations will be denied in a future release
3> hello world
4> how are you
5> happy new year
从Kafka中读取数据
从Kafka中读取数据，可能是Flink应用最广泛的一种方式。目前我的客户也使用这种方式进行流数据的处理。
从Kafka中读取数据，可以使用flink-connector-kafka。
创建一个Maven工程，加入下面的依赖：
<dependency>
<groupId>org.apache.flink</groupId>
<artifactId>flink-connector-kafka-0.11_2.12</artifactId>
<version>1.10.2</version>
</dependency>
程序代码：
package cn.jihui.flink
import java.util.Properties
import org.apache.flink.api.common.serialization.SimpleStringSchema
import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment
import org.apache.flink.streaming.connectors.kafka.FlinkKafkaConsumer011
object readKafka {
def main(args: Array[String]): Unit = {
val env = StreamExecutionEnvironment.getExecutionEnvironment
val properties = new Properties()
properties.setProperty("bootstrap.servers", "172.16.3.6:9092")
properties.setProperty("group.id", "data-group")
val streamData = env.addSource(new FlinkKafkaConsumer011[String]("sensor", new SimpleStringSchema, properties))
streamData.print()
env.execute()
}
}
启动Kafka
[bigdata@vm6 kafka-2.6.0]$ ./bin/kafka-server-start.sh -daemon config/server.properties
查看是否成功
[bigdata@vm6 ~]$ jps
8690 QuorumPeerMain
21068 Jps
10366 Kafka
[bigdata@vm6 ~]$
启动Kafka的测试脚本
[bigdata@vm6 bin]$ ./kafka-console-producer.sh --broker-list 172.16.3.6:9092 --topic sensor
>hello world
>happy new year
>what are you doing here?
>
当在Kafka的测试脚本中输入文本时，启动Flink程序可以接收到数据，并进行输出。
输出结果
"C:\Program Files\Java\jdk-11\bin\java.exe" "-javaagent:D:\Program Files\JetBrains\IntelliJ IDEA Community Edition 2019.3.3\lib\idea_rt.jar=60325:D:\Program Files\JetBrains\IntelliJ IDEA Community Edition 2019.3.3\bin" -Dfile.encoding=UTF-8 -classpath C:\Users\32985\IdeaProjects\flink_demo\target\classes;C:\Users\32985\.m2\repository\org\apache\flink\flink-scala_2.12\1.10.1\flink-scala_2.12-1.10.1.jar;C:\Users\32985\.m2\repository\org\apache\flink\flink-core\1.10.1\flink-core-1.10.1.jar;C:\Users\32985\.m2\repository\org\apache\flink\flink-annotations\1.10.1\flink-annotations-1.10.1.jar;C:
......
:\Users\32985\.m2\repository\net\jpountz\lz4\lz4\1.3.0\lz4-1.3.0.jar;C:\Users\32985\.m2\repository\org\xerial\snappy\snappy-java\1.1.2.6\snappy-java-1.1.2.6.jar;C:\Users\32985\.m2\repository\mysql\mysql-connector-java\5.1.46\mysql-connector-java-5.1.46.jar;D:\Bigdata\scala-2.12.18\lib\scala-library.jar;D:\Bigdata\scala-2.12.18\lib\scala-parser-combinators_2.12-1.0.7.jar;D:\Bigdata\scala-2.12.18\lib\scala-reflect.jar;D:\Bigdata\scala-2.12.18\lib\scala-swing_2.12-2.0.3.jar;D:\Bigdata\scala-2.12.18\lib\scala-xml_2.12-2.1.0.jar cn.jihui.flink.readKafka
SLF4J: Failed to load class "org.slf4j.impl.StaticLoggerBinder".
SLF4J: Defaulting to no-operation (NOP) logger implementation
SLF4J: See http://www.slf4j.org/codes.html#StaticLoggerBinder for further details.
WARNING: An illegal reflective access operation has occurred
WARNING: Illegal reflective access by org.apache.flink.api.java.ClosureCleaner (file:/C:/Users/32985/.m2/repository/org/apache/flink/flink-core/1.10.1/flink-core-1.10.1.jar) to field java.lang.String.value
WARNING: Please consider reporting this to the maintainers of org.apache.flink.api.java.ClosureCleaner
WARNING: Use --illegal-access=warn to enable warnings of further illegal reflective access operations
WARNING: All illegal access operations will be denied in a future release
7> hello world
7> happy new year
7> what are you doing here?
Process finished with exit code -1
从MySQL中读取数据
当需要从关系数据库中读取数据时，可以简单的JDBC方式进行读取。
程序代码：
package cn.jihui.flink
import java.sql.{DriverManager, ResultSet}
import org.apache.flink.streaming.api.functions.source.{RichSourceFunction, SourceFunction}
import org.apache.flink.streaming.api.scala.StreamExecutionEnvironment
import org.apache.flink.streaming.api.scala._
//case class SensorReading(id: String, timestamp: Long, temperature: Double)
object readMySQL {
def main(args: Array[String]): Unit = {
val env = StreamExecutionEnvironment.getExecutionEnvironment
val streamData = env.addSource(new MySQLSource)
streamData.print()
env.execute("read data from mysql")
}
}
class MySQLSource extends SourceFunction[SensorReading] {
var running: Boolean = true;
override def run(sourceContext: SourceFunction.SourceContext[SensorReading]): Unit = {
val strConn = "jdbc:mysql://172.16.3.6:3306/flink"
val conn = DriverManager.getConnection(strConn, "jihui", "111111")
val selectStmt = conn.prepareStatement("select * from t_sensor;")
val resultRs: ResultSet = selectStmt.executeQuery()
while (resultRs.next()) {
if (running) {
val id = resultRs.getString(1)
val timestamp = resultRs.getLong(2)
val temperature = resultRs.getDouble(3)
sourceContext.collect(SensorReading(id, timestamp, temperature))
}
}
resultRs.close()
selectStmt.close()
conn.close()
}
override def cancel(): Unit = {
running = false
}
}
输出内容：文章来源地址https://www.toymoban.com/news/detail-592602.html
"C:\Program Files\Java\jdk-11\bin\java.exe" "-javaagent:D:\Program Files\JetBrains\IntelliJ IDEA Community Edition 2019.3.3\lib\idea_rt.jar=61886:D:\Program Files\JetBrains\IntelliJ IDEA Community Edition 2019.3.3\bin" -Dfile.encoding=UTF-8 -classpath
......
C:\Users\32985\.m2\repository\org\apache\kafka\kafka-clients\0.11.0.2\kafka-clients-0.11.0.2.jar;C:\Users\32985\.m2\repository\net\jpountz\lz4\lz4\1.3.0\lz4-1.3.0.jar;C:\Users\32985\.m2\repository\org\xerial\snappy\snappy-java\1.1.2.6\snappy-java-1.1.2.6.jar;C:\Users\32985\.m2\repository\mysql\mysql-connector-java\5.1.46\mysql-connector-java-5.1.46.jar;D:\Bigdata\scala-2.12.18\lib\scala-library.jar;D:\Bigdata\scala-2.12.18\lib\scala-parser-combinators_2.12-1.0.7.jar;D:\Bigdata\scala-2.12.18\lib\scala-reflect.jar;D:\Bigdata\scala-2.12.18\lib\scala-swing_2.12-2.0.3.jar;D:\Bigdata\scala-2.12.18\lib\scala-xml_2.12-2.1.0.jar cn.jihui.flink.readMySQL
SLF4J: Failed to load class "org.slf4j.impl.StaticLoggerBinder".
SLF4J: Defaulting to no-operation (NOP) logger implementation
SLF4J: See http://www.slf4j.org/codes.html#StaticLoggerBinder for further details.
WARNING: An illegal reflective access operation has occurred
WARNING: Illegal reflective access by org.apache.flink.api.java.ClosureCleaner (file:/C:/Users/32985/.m2/repository/org/apache/flink/flink-core/1.10.1/flink-core-1.10.1.jar) to field java.lang.String.value
WARNING: Please consider reporting this to the maintainers of org.apache.flink.api.java.ClosureCleaner
WARNING: Use --illegal-access=warn to enable warnings of further illegal reflective access operations
WARNING: All illegal access operations will be denied in a future release
7> SensorReading(Sensor_4,1687944878278,42.6205)
1> SensorReading(Sensor_10,1687944879294,31.3545)
7> SensorReading(Sensor_7,1687944878278,16.3773)
1> SensorReading(Sensor_4,1687944879294,42.6205)
7> SensorReading(Sensor_8,1687944879294,7.3655)
7> SensorReading(Sensor_2,1687944878278,32.3747)
8> SensorReading(Sensor_1,1687944879294,20.0778)
8> SensorReading(Sensor_9,1687944878278,7.65736)
5> SensorReading(Sensor_3,1687944878278,32.9043)
6> SensorReading(Sensor_1,1687944880296,20.0778)
5> SensorReading(Sensor_10,1687944880296,31.3545)
2> SensorReading(Sensor_8,1687944880296,7.3655)
6> SensorReading(Sensor_6,1687944878278,4.37994)
2> SensorReading(Sensor_5,1687944880296,42.1028)
2> SensorReading(Sensor_2,1687944880296,32.3747)
4> SensorReading(Sensor_10,1687944878278,31.3545)
4> SensorReading(Sensor_9,1687944879294,7.65736)
4> SensorReading(Sensor_9,1687944880296,7.65736)
5> SensorReading(Sensor_2,1687944879294,32.3747)
5> SensorReading(Sensor_6,1687944879294,4.37994)
3> SensorReading(Sensor_5,1687944879294,42.1028)
4> SensorReading(Sensor_7,1687944879294,16.3773)
6> SensorReading(Sensor_5,1687944878278,42.1028)
8> SensorReading(Sensor_8,1687944878278,7.3655)
1> SensorReading(Sensor_4,1687944880296,42.6205)
6> SensorReading(Sensor_3,1687944879294,32.9043)
3> SensorReading(Sensor_7,1687944880296,16.3773)
8> SensorReading(Sensor_6,1687944880296,4.37994)
3> SensorReading(Sensor_3,1687944880296,32.9043)
3> SensorReading(Sensor_1,1687944878278,20.0778)
Process finished with exit code 0
从自定义数据源读取数据
当需要对Flink进行一些性能测试时，可以使用自定义数据源来简化测试过程。
Flink支持自定义数据源，可以使用循环生成所需要格式的测试数据，使用方式非常灵活。
程序代码：
package cn.jihui.flink
import java.util.Random
import org.apache.flink.streaming.api.functions.source.SourceFunction
import org.apache.flink.streaming.api.scala.StreamExecutionEnvironment
import org.apache.flink.streaming.api.scala._
case class SensorReading(id: String, timestamp: Long, temperature: Double)
object readCustom {
def main(args: Array[String]): Unit = {
val env = StreamExecutionEnvironment.getExecutionEnvironment
val dataCustom = env.addSource(new MySensorSource())
dataCustom.print()
env.execute("custom data source")
}
}
class MySensorSource extends SourceFunction[SensorReading] {
var running: Boolean = true
override def run(sourceContext: SourceFunction.SourceContext[SensorReading]): Unit = {
val rand = new Random()
var currTemp = 1.to(10).map(i => ("Sensor_" + i, rand.nextDouble() * 50))
while(running) {
val currTime = System.currentTimeMillis()
currTemp.map(
data => (data._1, data._2 + rand.nextGaussian())
)
currTemp.foreach(
data => sourceContext.collect(SensorReading(data._1, currTime, data._2))
)
}
}
override def cancel(): Unit = running = false
}
运行程序后，会产生源源不断的数据。文章来源：https://www.toymoban.com/news/detail-592602.html
输出内容：
"C:\Program Files\Java\jdk-11\bin\java.exe" "-javaagent:D:\Program Files\JetBrains\IntelliJ IDEA Community Edition 2019.3.3\lib\idea_rt.jar=62739:D:\Program Files\JetBrains\IntelliJ IDEA Community Edition 2019.3.3\bin" -Dfile.encoding=UTF-8 -classpath C:\Users\32985\IdeaProjects\flink_demo1\out\production\flink_demo1;D:\Bigdata\scala-2.12.18\lib\scala-library.jar;D:\Bigdata\scala-2.12.18\lib\scala-parser-combinators_2.12-1.0.7.jar;D:\Bigdata\scala-2.12.18\lib\scala-reflect.jar;D:\Bigdata\scala-2.12.18\lib\scala-swing_2.12-2.0.3.jar;D:\Bigdata\scala-2.12.18\lib\scala-xml_2.12-2.1.0.jar;D:\Bigdata\flink-1.10.1\lib\log4j-1.2.17.jar;D:\Bigdata\flink-1.10.1\lib\slf4j-log4j12-1.7.15.jar;D:\Bigdata\flink-1.10.1\lib\flink-dist_2.12-1.10.1.jar;D:\Bigdata\flink-1.10.1\lib\flink-table_2.12-1.10.1.jar;D:\Bigdata\flink-1.10.1\lib\flink-table-blink_2.12-1.10.1.jar cn.jihui.flink.readCustom
log4j:WARN No appenders could be found for logger (org.apache.flink.api.scala.ClosureCleaner$).
log4j:WARN Please initialize the log4j system properly.
log4j:WARN See http://logging.apache.org/log4j/1.2/faq.html#noconfig for more info.
WARNING: An illegal reflective access operation has occurred
WARNING: Illegal reflective access by org.apache.flink.api.java.ClosureCleaner (file:/D:/Bigdata/flink-1.10.1/lib/flink-dist_2.12-1.10.1.jar) to field java.lang.String.value
WARNING: Please consider reporting this to the maintainers of org.apache.flink.api.java.ClosureCleaner
WARNING: Use --illegal-access=warn to enable warnings of further illegal reflective access operations
WARNING: All illegal access operations will be denied in a future release
7> SensorReading(Sensor_4,1687944878278,42.62052120270371)
1> SensorReading(Sensor_6,1687944878278,4.3799399141547735)
3> SensorReading(Sensor_8,1687944878278,7.365503979569099)
5> SensorReading(Sensor_2,1687944878278,32.374658798648426)
6> SensorReading(Sensor_3,1687944878278,32.9042516066123)
2> SensorReading(Sensor_7,1687944878278,16.37730093567341)
8> SensorReading(Sensor_5,1687944878278,42.1027668775983)
4> SensorReading(Sensor_1,1687944878278,20.077801500835886)
5> SensorReading(Sensor_10,1687944878278,31.35446091105863)
4> SensorReading(Sensor_9,1687944878278,7.657356771011931)
5> SensorReading(Sensor_8,1687944879294,7.365503979569099)
3> SensorReading(Sensor_6,1687944879294,4.3799399141547735)
6> SensorReading(Sensor_1,1687944879294,20.077801500835886)
1> SensorReading(Sensor_4,1687944879294,42.62052120270371)
4> SensorReading(Sensor_7,1687944879294,16.37730093567341)
2> SensorReading(Sensor_5,1687944879294,42.1027668775983)
6> SensorReading(Sensor_9,1687944879294,7.657356771011931)
7> SensorReading(Sensor_2,1687944879294,32.374658798648426)
8> SensorReading(Sensor_3,1687944879294,32.9042516066123)
7> SensorReading(Sensor_10,1687944879294,31.35446091105863)
4> SensorReading(Sensor_5,1687944880296,42.1027668775983)
1> SensorReading(Sensor_2,1687944880296,32.374658798648426)
5> SensorReading(Sensor_6,1687944880296,4.3799399141547735)
7> SensorReading(Sensor_8,1687944880296,7.365503979569099)
6> SensorReading(Sensor_7,1687944880296,16.37730093567341)
2> SensorReading(Sensor_3,1687944880296,32.9042516066123)
3> SensorReading(Sensor_4,1687944880296,42.62052120270371)
8> SensorReading(Sensor_1,1687944880296,20.077801500835886)
1> SensorReading(Sensor_10,1687944880296,31.35446091105863)
8> SensorReading(Sensor_9,1687944880296,7.657356771011931)
Process finished with exit code -1
到了这里，关于Flink读取数据的5种方式（文件，Socket，Kafka，MySQL，自定义数据源）的文章就介绍完了。如果您还想了解更多内容，请在右上角搜索TOY模板网以前的文章或继续浏览下面的相关文章，希望大家以后多多支持TOY模板网！
