聊聊flink的DualKeyMap
序
【聊聊flink的DualKeyMap】本文主要研究一下flink的DualKeyMap
实例
@Test
public void testKeySets() {
final Random random = new Random();
final int capacity = 10;
final Set> keys = new HashSet<>(capacity);
for (int i = 0;
i < capacity;
i++) {
int keyA = random.nextInt();
int keyB = random.nextInt();
keys.add(Tuple2.of(keyA, keyB));
}final DualKeyMap dualKeyMap = new DualKeyMap<>(capacity);
for (Tuple2 key : keys) {
dualKeyMap.put(key.f0, key.f1, "foobar");
}assertThat(dualKeyMap.keySetA(), Matchers.equalTo(keys.stream().map(t -> t.f0).collect(Collectors.toSet())));
assertThat(dualKeyMap.keySetB(), Matchers.equalTo(keys.stream().map(t -> t.f1).collect(Collectors.toSet())));
}
- DualKeyMap有两个key，put值的时候，需要指定keyA及keyB
public class DualKeyMap {private final HashMap> aMap;
private final HashMap bMap;
private transient Collection values;
public DualKeyMap(int initialCapacity) {
this.aMap = new HashMap<>(initialCapacity);
this.bMap = new HashMap<>(initialCapacity);
}public int size() {
return aMap.size();
}public V getKeyA(A aKey) {
final Tuple2 value = https://www.it610.com/article/aMap.get(aKey);
if (value != null) {
return value.f1;
} else {
return null;
}
}public V getKeyB(B bKey) {
final A aKey = bMap.get(bKey);
if (aKey != null) {
return aMap.get(aKey).f1;
} else {
return null;
}
}public V put(A aKey, B bKey, V value) {
Tuple2 aValue = https://www.it610.com/article/aMap.put(aKey, Tuple2.of(bKey, value));
bMap.put(bKey, aKey);
if (aValue != null) {
return aValue.f1;
} else {
return null;
}
}public boolean containsKeyA(A aKey) {
return aMap.containsKey(aKey);
}public boolean containsKeyB(B bKey) {
return bMap.containsKey(bKey);
}public V removeKeyA(A aKey) {
Tuple2 aValue = https://www.it610.com/article/aMap.remove(aKey);
if (aValue != null) {
bMap.remove(aValue.f0);
return aValue.f1;
} else {
return null;
}
}public V removeKeyB(B bKey) {
A aKey = bMap.remove(bKey);
if (aKey != null) {
Tuple2 aValue = https://www.it610.com/article/aMap.remove(aKey);
if (aValue != null) {
return aValue.f1;
} else {
return null;
}
} else {
return null;
}
}public Collection values() {
Collection vs = values;
if (vs == null) {
vs = new Values();
values = vs;
}return vs;
}public Set keySetA() {
return aMap.keySet();
}public Set keySetB() {
return bMap.keySet();
}public void clear() {
aMap.clear();
bMap.clear();
}// -----------------------------------------------------------------------
// Inner classes
// -----------------------------------------------------------------------/**
* Collection which contains the values of the dual key map.
*/
private final class Values extends AbstractCollection {@Override
public Iterator iterator() {
return new ValueIterator();
}@Override
public int size() {
return aMap.size();
}
}/**
* Iterator which iterates over the values of the dual key map.
*/
private final class ValueIterator implements Iterator {private final Iterator> iterator = aMap.values().iterator();
@Override
public boolean hasNext() {
return iterator.hasNext();
}@Override
public V next() {
Tuple2 value = https://www.it610.com/article/iterator.next();
return value.f1;
}
}
}
- DualKeyMap定义了三个泛型，分别是A，B，V，即keyA，keyB，value的泛型；它维护了两个HashMap，其中aMap的key为keyA，value为Tuple2
- DualKeyMap提供了getKeyA、getKeyB、containsKeyA、containsKeyB、removeKeyA、removeKeyB、keySetA、keySetB、size、put、values、clear方法
- values方法返回的是Values，它继承了AbstractCollection，它的iterator方法返回的是ValueIterator；ValueIterator实现了Iterator接口，其内部使用的是aMap.values().iterator()
- DualKeyMap定义了三个泛型，分别是A，B，V，即keyA，keyB，value的泛型；它维护了两个HashMap，其中aMap的key为keyA，value为Tuple2
- DualKeyMap提供了getKeyA、getKeyB、containsKeyA、containsKeyB、removeKeyA、removeKeyB、keySetA、keySetB、size、put、values、clear方法；put值的时候，需要指定keyA及keyB
- values方法返回的是Values，它继承了AbstractCollection，它的iterator方法返回的是ValueIterator；ValueIterator实现了Iterator接口，其内部使用的是aMap.values().iterator()
- DualKeyMap
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