案例一：实现topic之间的流传输
一、Kafka Java代码
创建maven过程，导入以下依赖
org.apache.kafka
kafka_2.11
2.0.0
org.apache.kafka
kafka-streams
2.0.0
代码部分
public class MyStream {
public static void main(String[] args) {
Properties prop = new Properties();
prop.put(StreamsConfig.APPLICATION_ID_CONFIG,"mystream");
prop.put(StreamsConfig.BOOTSTRAP_SERVERS_CONFIG,"192.168.247.201:9092");
prop.put(StreamsConfig.DEFAULT_KEY_SERDE_CLASS_CONFIG, Serdes.String().getClass());
prop.put(StreamsConfig.DEFAULT_VALUE_SERDE_CLASS_CONFIG,Serdes.String().getClass());
// 创建流构造器
StreamsBuilder builder = new StreamsBuilder();
// 构建好builder 将mystreamin topic中的数据写入到 mystreamout topic中
builder.stream("mystreamin").to("mystreamout");
final Topology topo = builder.build();
final KafkaStreams streams = new KafkaStreams(topo, prop);
final CountDownLatch latch = new CountDownLatch(1);
Runtime.getRuntime().addShutdownHook(new Thread("stream"){
@Override
public void run() {
streams.close();
latch.countDown();
}
});
try {
streams.start();
latch.await();
} catch (InterruptedException e) {
e.printStackTrace();
}
System.exit(0);
}
}二、Kafka Shell 命令
1、创建Topic
`kafka-topics.sh --create --zookeeper 192.168.247.201:2181 --topic mystreamin --partitions 1 --replication-factor 1
kafka-topics.sh --create --zookeeper 192.168.247.201:2181 --topic mystreamout --partitions 1 --replication-factor 1`
* 1
* 2
查看Topic
kafka-topics.sh --zookeeper 192.168.247.201:2181 --list
2、运行Java代码，执行以下步骤：
生产消息
kafka-console-producer.sh --topic mystreamin --broker-list 127.0.0.1:9092
消费消息
kafka-console-consumer.sh --topic mystreamout --bootstrap-server 127.0.0.1:9092 --from-beginning
案例二：WordCount Stream API
一、Kafka Java代码
代码部分
public class WordCountStream {
public static void main(String[] args) {
Properties prop = new Properties();
prop.put(StreamsConfig.APPLICATION_ID_CONFIG,"wordcount");
prop.put(StreamsConfig.BOOTSTRAP_SERVERS_CONFIG,"192.168.247.201:9092");
prop.put(StreamsConfig.COMMIT_INTERVAL_MS_CONFIG,3000);
prop.put(ConsumerConfig.AUTO_OFFSET_RESET_DOC,"earliest"); // earliest latest
prop.put(ConsumerConfig.ENABLE_AUTO_COMMIT_CONFIG,"false"); // 设置手动提交方式
prop.put(StreamsConfig.DEFAULT_KEY_SERDE_CLASS_CONFIG, Serdes.String().getClass());
prop.put(StreamsConfig.DEFAULT_VALUE_SERDE_CLASS_CONFIG,Serdes.String().getClass());
// 创建流构造器
// wordcount-input
// hello world
// hello java
StreamsBuilder builder = new StreamsBuilder();
KTable count = builder.stream("wordcount-input") // 从kafka中一条一条的取数据
.flatMapValues( // 返回压扁后的数据
(value) -> { // 对数据进行按空格切割，返回List集合
String[] split = value.toString().split(" ");
List strings = Arrays.asList(split);
return strings;
}) // key:null value:hello ,key:null value:world ,key:null value:hello ,key:null value:java
.map((k, v) -> {
return new KeyValue(v,"1");
}).groupByKey().count();
count.toStream().foreach((k,v) -> {
System.out.println("key:"+k+" value:"+v);
});
count.toStream().map((x,y) -> {
return new KeyValue(x,y.toString());
}).to("wordcount-out");
final Topology topo = builder.build();
final KafkaStreams streams = new KafkaStreams(topo, prop);
final CountDownLatch latch = new CountDownLatch(1);
Runtime.getRuntime().addShutdownHook(new Thread("stream"){
@Override
public void run() {
streams.close();
latch.countDown();
}
});
try {
streams.start();
latch.await();
} catch (InterruptedException e) {
e.printStackTrace();
}
System.exit(0);
}
} 
二、Kafka Shell 命令
1、创建Topic
kafka-topics.sh --create --zookeeper 192.168.247.201:2181 --topic wordcount-input --partitions 1 --replication-factor 1
kafka-topics.sh --create --zookeeper 192.168.247.201:2181 --topic wordcount-out --partitions 1 --replication-factor 1
**2、运行Java代码，执行以下步骤：
生产消息**
kafka-console-producer.sh --topic wordcount-input --broker-list 127.0.0.1:9092
消费消息
kafka-console-consumer.sh --topic wordcount-out --bootstrap-server 127.0.0.1:9092 --from-beginning
显示key消费消息
kafka-console-consumer.sh --topic wordcount-out --bootstrap-server 127.0.0.1:9092 --property print.key=true --from-beginning
案例三：利用Kafka流实现对输入数字的求和
一、Kafka Java代码
public class SumStream {
public static void main(String[] args) {
Properties prop = new Properties();
prop.put(StreamsConfig.APPLICATION_ID_CONFIG,"sumstream");
prop.put(StreamsConfig.BOOTSTRAP_SERVERS_CONFIG,"192.168.247.201:9092");
prop.put(StreamsConfig.COMMIT_INTERVAL_MS_CONFIG,3000);
prop.put(ConsumerConfig.AUTO_OFFSET_RESET_DOC,"earliest"); // earliest latest
prop.put(ConsumerConfig.ENABLE_AUTO_COMMIT_CONFIG,"false"); // 设置手动提交方式
prop.put(StreamsConfig.DEFAULT_KEY_SERDE_CLASS_CONFIG, Serdes.String().getClass());
prop.put(StreamsConfig.DEFAULT_VALUE_SERDE_CLASS_CONFIG,Serdes.String().getClass());
StreamsBuilder builder = new StreamsBuilder();
KStream source = builder.stream("suminput");
source.map((key,value) ->
new KeyValue("sum: ",value.toString())
).groupByKey().reduce((x,y) ->{
System.out.println("x: "+x+" y: "+y);
Integer sum = Integer.valueOf(x)+Integer.valueOf(y);
System.out.println("sum: "+sum);
return sum.toString();
});
final Topology topo = builder.build();
final KafkaStreams streams = new KafkaStreams(topo, prop);
final CountDownLatch latch = new CountDownLatch(1);
Runtime.getRuntime().addShutdownHook(new Thread("stream"){
@Override
public void run() {
streams.close();
latch.countDown();
}
});
try {
streams.start();
latch.await();
} catch (InterruptedException e) {
e.printStackTrace();
}
System.exit(0);
}
}
二、Kafka Shell 命令
1、创建Topic
kafka-topics.sh --create --zookeeper 192.168.247.201:2181 --topic suminput --partitions 1 --replication-factor 1
**2、运行Java代码，执行以下步骤：
生产消息**
kafka-console-producer.sh --topic suminput --broker-list 127.0.0.1:9092
案例四：Kafka Stream实现不同窗口的流处理
一、Kafka Java代码
package cn.kgc.kb09;
import org.apache.kafka.clients.consumer.ConsumerConfig;
import org.apache.kafka.common.protocol.types.Field;
import org.apache.kafka.common.serialization.Serdes;
import org.apache.kafka.streams.*;
import org.apache.kafka.streams.kstream.KStream;
import org.apache.kafka.streams.kstream.SessionWindows;
import org.apache.kafka.streams.kstream.TimeWindows;
import java.time.Duration;
import java.util.Arrays;
import java.util.Properties;
import java.util.concurrent.CountDownLatch;
/**
* @Qianchun
* @Date 2020/12/16
* @Description
*/
public class WindowStream {
public static void main(String[] args) {
Properties prop = new Properties();
// 不同的窗口流不能使用相同的应用ID
prop.put(StreamsConfig.APPLICATION_ID_CONFIG,"SessionWindow");
prop.put(StreamsConfig.BOOTSTRAP_SERVERS_CONFIG,"192.168.247.201:9092");
prop.put(StreamsConfig.COMMIT_INTERVAL_MS_CONFIG,3000);
prop.put(ConsumerConfig.AUTO_OFFSET_RESET_DOC,"earliest"); // earliest latest
prop.put(ConsumerConfig.ENABLE_AUTO_COMMIT_CONFIG,"false"); // 设置手动提交方式
prop.put(StreamsConfig.DEFAULT_KEY_SERDE_CLASS_CONFIG, Serdes.String().getClass());
prop.put(StreamsConfig.DEFAULT_VALUE_SERDE_CLASS_CONFIG,Serdes.String().getClass());
StreamsBuilder builder = new StreamsBuilder();
KStream source = builder.stream("windowdemo");
source.flatMapValues(value -> Arrays.asList(value.toString().split("s+")))
.map((x,y) -> {
return new KeyValue(y,"1");
}).groupByKey()
//以下所有窗口的时间均可通过下方参数调设
// Tumbling Time Window(窗口为5秒,5秒内有效)
// .windowedBy(TimeWindows.of(Duration.ofSeconds(5).toMillis()))
// Hopping Time Window(窗口为5秒,每次移动2秒,所以若5秒内只输入一次会出现5/2+1=3次)
// .windowedBy(TimeWindows.of(Duration.ofSeconds(5).toMillis())
// .advanceBy(Duration.ofSeconds(2).toMillis()))
// Session Time Window(20秒内只要输入Session就有效,距离下一次输入超过20秒Session失效,所有从重新从0开始)
// .windowedBy(SessionWindows.with(Duration.ofSeconds(20).toMillis()))
.count().toStream().foreach((x,y) -> {
System.out.println("x: "+x+" y:"+y);
});
final Topology topo = builder.build();
final KafkaStreams streams = new KafkaStreams(topo, prop);
final CountDownLatch latch = new CountDownLatch(1);
Runtime.getRuntime().addShutdownHook(new Thread("stream"){
@Override
public void run() {
streams.close();
latch.countDown();
}
});
try {
streams.start();
latch.await();
} catch (InterruptedException e) {
e.printStackTrace();
}
System.exit(0);
}
} 二、Kafka Shell 命令
1、创建Topic
kafka-topics.sh --create --zookeeper 192.168.247.201:2181 --topic windowdemo --partitions 1 --replication-factor 1
**2、运行Java代码，执行以下步骤：
生产消息**
kafka-console-producer.sh --topic windowdemo --broker-list 127.0.0.1:9092
注意：
ERROR：
- Exception in thread “sum-a3bbe4d0-4cc9-4812-a7a0-e650a8a60c9f-StreamThread-1” java.lang.IllegalArgumentException: Window endMs time cannot be smaller than window startMs time.
- 数组越界
解决方案：
- 大概率是窗口ID一致，请修改
prop.put(StreamsConfig.APPLICATION_ID_CONFIG, "sessionwindow");的参数。
- 大概率是窗口ID一致，请修改