Storm：如何将String Array从一个螺栓传递到另一个螺栓？

Question

This is how I am emitting the data

collector.emit("stream", new Values(sessionid,tables));

Where sessionid and tables are ArrayList<String>

I am not sure how the bolt which will receive the data will get it as I didn't find anything to get the value in Tuple.

This is how my execute method of receiving bolt will look.

public void execute(Tuple input, BasicOutputCollector collector) {
     ArrayList<String> keyspace = input./*What to add here*/(0);
     ArrayList<String> table = input./*What to add here*/(1);    
}

Alternatively, I am thinking of merging the value of the ArrayList in a comma separated string and pass it as a string and then split it and save it in ArrayList in the receiving bolt.

But, is there any clean way to pass ArrayList to Storm bolts?

Answer 1

You can pass ArrayList without problems. You just need to use Tuple.getValue(int) (or Tuple.getValueByField(String) ) and cast to the correct type:

public void execute(Tuple input, BasicOutputCollector collector) {
    ArrayList<String> keyspace = (ArrayList<String>)input.getValue(0);
    ArrayList<String> table = (ArrayList<String>)input.getValue(1);
}