如何连接两个流并在Flink中操作它们？

import org.apache.flink.api.common.functions.FlatMapFunction;
import org.apache.flink.api.java.tuple.Tuple2;
import org.apache.flink.streaming.api.datastream.ConnectedStreams;
import org.apache.flink.streaming.api.datastream.DataStream;
import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment;
import org.apache.flink.util.Collector;

public class StreamConnectionExample {
    public static void main(String[] args) throws Exception {
        // 创建执行环境
        StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();

        // 创建两个流
        DataStream<String> stream1 = env.fromElements("Hello", "Flink", "Stream");
        DataStream<Integer> stream2 = env.fromElements(1, 2, 3);

        // 连接两个流
        ConnectedStreams<String, Integer> connectedStreams = stream1.connect(stream2);

        // 对连接后的流进行操作
        DataStream<String> result = connectedStreams.flatMap(new FlatMapFunction<String, String>() {
            @Override
            public void flatMap(String value, Collector<String> out) {
                out.collect(value.toUpperCase());
            }
        });

        // 输出结果
        result.print();

        // 执行任务
        env.execute("Stream Connection Example");
    }
}