DataStream 在WindowFunction方法中String转 DataStream<String>的程序代码
时间: 2024-05-20 20:16:28 浏览: 13
下面是一个示例代码,其中使用`WindowFunction`将`String`类型的数据流转换为`DataStream<String>`类型的数据流:
```java
import org.apache.flink.api.common.functions.MapFunction;
import org.apache.flink.api.common.functions.ReduceFunction;
import org.apache.flink.api.java.functions.KeySelector;
import org.apache.flink.api.java.tuple.Tuple2;
import org.apache.flink.streaming.api.datastream.DataStream;
import org.apache.flink.streaming.api.datastream.WindowedStream;
import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment;
import org.apache.flink.streaming.api.functions.windowing.WindowFunction;
import org.apache.flink.streaming.api.windowing.time.Time;
import org.apache.flink.streaming.api.windowing.windows.TimeWindow;
import org.apache.flink.util.Collector;
public class StringToDataStreamExample {
public static void main(String[] args) throws Exception {
// set up the streaming execution environment
final StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();
// define the data source
DataStream<String> text = env.socketTextStream("localhost", 9999);
// define the window size and slide interval
Time windowSize = Time.seconds(5);
Time slideInterval = Time.seconds(1);
// apply a window function to the stream
WindowedStream<String, String, TimeWindow> windowedStream = text.keyBy(new KeySelector<String, String>() {
@Override
public String getKey(String value) throws Exception {
return value;
}
}).timeWindow(windowSize, slideInterval);
// convert the windowed stream to a data stream
DataStream<String> result = windowedStream.apply(new WindowFunction<String, String, String, TimeWindow>() {
@Override
public void apply(String key, TimeWindow window, Iterable<String> input, Collector<String> out) throws Exception {
StringBuilder sb = new StringBuilder();
for (String s : input) {
sb.append(s);
sb.append(" ");
}
out.collect(sb.toString().trim());
}
});
// print the result
result.print();
// execute program
env.execute("String to DataStream Example");
}
}
```
在上面的示例中,我们使用`socketTextStream`从本地套接字读取输入数据。然后,我们使用`keyBy`方法将输入数据流分区为不同的键,以便在窗口函数中对每个键应用窗口。我们定义了一个`WindowFunction`来将窗口中的输入数据合并为一个字符串,并将其添加到`out`收集器中。最后,我们将窗口数据流转换为数据流并打印结果。