Storm Trident示例Aggregator

static class State {  
        int count = 0;  
    }  

FixedBatchSpout spout = new FixedBatchSpout(new Fields("user", "score"), 3,    
                new Values("nickt1", 4),   
                new Values("nickt2", 7),    
                new Values("nickt3", 8),   
                new Values("nickt4", 9),    
                new Values("nickt5", 7),   
                new Values("nickt6", 11),   
                new Values("nickt7", 5)   
                );   
        spout.setCycle(false);   
        TridentTopology topology = new TridentTopology();   
        topology.newStream("spout1", spout)   
                .shuffle()   
                .each(new Fields("user", "score"),new Debug("shuffle print:"))  
                .parallelismHint(5)  
                .aggregate(new Fields("score"), new BaseAggregator<State>() {  
                    //在处理每一个batch的数据之前，调用1次  
                    //空batch也会调用  
                    @Override  
                    public State init(Object batchId, TridentCollector collector) {  
                        return new State();  
                    }  
                    //batch中的每个tuple各调用1次  
                    @Override  
                    public void aggregate(State state, TridentTuple tuple, TridentCollector collector) {  
                        state.count = tuple.getInteger(0) + state.count;  
                    }  
                    //batch中的所有tuples处理完成后调用   
                    @Override  
                    public void complete(State state, TridentCollector collector) {  
                        collector.emit(new Values(state.count));  
                    }  
                      
                }, new Fields("sum"))  
                .each(new Fields("sum"),new Debug("sum print:"))  
                .parallelismHint(5);