java - Flink，如何使用可变对象（IntValue，LongValue，...）？

Question

假设我有 2 个平面图实现，

public class Foobar implements FlatMapFunction<Foo, Tuple2<String, Bar>> {
@Override
public void flatMap(Foo in, Collector<Tuple2<String, Bar>> out) throws Exception {
    String id = in.getId();
    if(!"bad_id".equals(id)) {
        Bar bar = ...; // some code to build Bar instance from Foo
        out.collect(new Tuple2<>(id, bar));
    }
}}



public class Foobar implements FlatMapFunction<Foo, Tuple2<String, Bar>> {
private Bar bar;
private Tuple2<String, Bar> t2 = new Tuple2<>();
private StringValue id = new StringValue();

@Override
public void flatMap(Foo in, Collector<Tuple2<String, Bar>> out) throws Exception {
    id.setValue(in.getId());
    if(!"bad_id".equals(id.getValue())) {
        bar = ...; // some code to build Bar instance from Foo
        t2.f0 = id.getValue();
        t2.f1 = bar;
        out.collect(t2);
    }
}}

1. 从性能的角度来看，第二个更好吗？
2. 这是使用StringValue的正确方法吗？
3. 是否还需要将返回类型更改为 Tuple2<StringValue, Bar>，而不是 Tuple2<String, Bar>？

标签： javaapache-flink