太原市建设银行网站首页,做网站文字要求,卫龙的网站是谁做的,温州微信网站定制Immutable的集合体系#xff0c;还有中很重要的集合没有介绍#xff0c;就是ImmutableMap#xff0c;通过UML图#xff0c;可以看出ImmutableMap的结构体系。 首先来看一下ImmutableBiMap#xff0c;因为普通ImmutableMap的实现依赖于它。ImmutableBiMap在ImmutableMap的基…Immutable的集合体系还有中很重要的集合没有介绍就是ImmutableMap通过UML图可以看出ImmutableMap的结构体系。 首先来看一下ImmutableBiMap因为普通ImmutableMap的实现依赖于它。ImmutableBiMap在ImmutableMap的基础上加入inverse()等方法可以使键值反转。ImmutableBiMap的构造也是根据元素个数的不同使用不同的实现0--EmptyImmutablBiMap1--SingletonImmutablBiMapn(n2)--RegularImmubtalMap代码如下所示 public abstract class ImmutableBiMapK, V extends ImmutableMapK, V implements BiMapK, V {public static K, V ImmutableBiMapK, V of() {//Empty元素内部不维护存储结构inverse()方法直接返回thisreturn (ImmutableBiMapK, V) EmptyImmutableBiMap.INSTANCE;}public static K, V ImmutableBiMapK, V of(K k1, V v1) {//单个元素构造时返回此类内部维护两个元素K,Vinverse()时返回V,K的SingletonImmutableBiMapreturn new SingletonImmutableBiMapK, V(k1, v1);}public static K, V ImmutableBiMapK, V of(K k1, V v1, K k2, V v2) {//多个元素构造是返回此类内部维护两个Entry[]集合一个以key作为hashbucket的位置 //另一个以value作为hashbucket的位置用于inverse()的时候key-value的反转return new RegularImmutableBiMapK, V(entryOf(k1, v1), entryOf(k2, v2));}
} copyOf()方法在ImmutableCollections中实现的原则就是如果copyOf()的还是一份ImmutableCollections集合那么只是进行引用的赋值因为集合本身不可变。 看过ImmutableBiMap之后在回头看ImmutableMap就简单了很多只是在ImmutableBiMap基础上去除了inverse()方法并在内部为户单一数组hashbucket 不需要维护反转的数组。在无元素和单一元素构造的时候直接调用ImmutableBiMap.of()和ImmutableBiMap.of(K,V)方法代码如下所示 public abstract class ImmutableMapK, V implements MapK, V, Serializable {/*** Returns the empty map. This map behaves and performs comparably to* {link Collections#emptyMap}, and is preferable mainly for consistency* and maintainability of your code.*/public static K, V ImmutableMapK, V of() {return ImmutableBiMap.of();}/*** Returns an immutable map containing a single entry. This map behaves and* performs comparably to {link Collections#singletonMap} but will not accept* a null key or value. It is preferable mainly for consistency and* maintainability of your code.*/public static K, V ImmutableMapK, V of(K k1, V v1) {return ImmutableBiMap.of(k1, v1);}
} 多个元素构造的时候返回RegularImmubtalMap与RegularImmutableBiMap内部实现大同小异去除对反转值-键的数组维护去除inverse()等方法。 最后简单的阐述一下ImmutableSortedMap的实现ImmutableMap单一元素和空元素的实现就不详细说了有兴趣的读者可以自己看看。多元素实现的时候 ImmutableSortedMap的具体实现类是RegularImmutableSortedMap有意思的是它的内部维护key和value的数据结构是两个List那么可想而知排序早在构造的时候就已经完成了而事实确实是这样具体代码如下所示 SuppressWarnings(unchecked)public static K extends Comparable? super K, V ImmutableSortedMapK, V of(K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4) {//将排序器和entires传入fromEntries方法return fromEntries(Ordering.natural(), false, 4, entryOf(k1, v1), entryOf(k2, v2),entryOf(k3, v3), entryOf(k4, v4));} static K, V ImmutableSortedMapK, V fromEntries(Comparator? super K comparator, boolean sameComparator, int size, EntryK, V... entries) {for (int i 0; i size; i) {EntryK, V entry entries[i];entries[i] entryOf(entry.getKey(), entry.getValue());}if (!sameComparator) {sortEntries(comparator, size, entries);//遍历entries排序validateEntries(size, entries, comparator);}return fromSortedEntries(comparator, size, entries);} static K, V ImmutableSortedMapK, V fromSortedEntries( Comparator? super K comparator,int size,EntryK, V[] entries) {if (size 0) {return emptyMap(comparator);}//遍历排序之后的entries分开key和value分别组成各自的ListImmutableList.BuilderK keyBuilder ImmutableList.builder();ImmutableList.BuilderV valueBuilder ImmutableList.builder();for (int i 0; i size; i) {EntryK, V entry entries[i];keyBuilder.add(entry.getKey());valueBuilder.add(entry.getValue());}return new RegularImmutableSortedMapK, V(new RegularImmutableSortedSetK(keyBuilder.build(), comparator),valueBuilder.build());
} ImmutableMap中的Entry也是被Guava重新实现增加了bucket的计算逻辑如下图UML AbstractMapEntry在原有Map.entry基础上将写操作置为直接抛异常ImmutableEntry实现getKey()和getValue()ImmutableMapEntry再加入bucket的计算和维护方法(链表)最终反映到NonTerminalMapEntry和TerminalEntry对于这两个类TerminalEntry为bucket链表的尾结点所以实现如下 static final class TerminalEntryK, V extends ImmutableMapEntryK, V {TerminalEntry(ImmutableMapEntryK, V contents) {super(contents);}TerminalEntry(K key, V value) {super(key, value);}OverrideNullableImmutableMapEntryK, V getNextInKeyBucket() {//尾节点所以没有nuextreturn null;}OverrideNullableImmutableMapEntryK, V getNextInValueBucket() {//尾节点所以没有nuextreturn null;}} 而NonTerminalMapEntry的构造则需要传入下一个Entry private static final class NonTerminalMapEntryK, V extends ImmutableMapEntryK, V {private final ImmutableMapEntryK, V nextInKeyBucket;NonTerminalMapEntry(K key, V value, ImmutableMapEntryK, V nextInKeyBucket) {super(key, value);this.nextInKeyBucket nextInKeyBucket;}NonTerminalMapEntry(ImmutableMapEntryK, V contents, ImmutableMapEntryK, V nextInKeyBucket) {super(contents);this.nextInKeyBucket nextInKeyBucket;}OverrideImmutableMapEntryK, V getNextInKeyBucket() {//同一个bucket中的下一个Entryreturn nextInKeyBucket;}OverrideNullableImmutableMapEntryK, V getNextInValueBucket() {//BiMap才会维护Value的Bucketreturn null;}} 那么在构造的时候如果产生hash冲突就是用nonTerminalMapEntry代码如下所示 RegularImmutableMap(Entry?, ?[] theEntries) {int size theEntries.length;entries createEntryArray(size);int tableSize Hashing.closedTableSize(size, MAX_LOAD_FACTOR);table createEntryArray(tableSize);mask tableSize - 1;for (int entryIndex 0; entryIndex size; entryIndex) {SuppressWarnings(unchecked) // all our callers carefully put in only EntryK, VsEntryK, V entry (EntryK, V) theEntries[entryIndex];K key entry.getKey();V value entry.getValue();checkEntryNotNull(key, value);int tableIndex Hashing.smear(key.hashCode()) mask;Nullable ImmutableMapEntryK, V existing table[tableIndex];// prepend, not append, so the entries can be immutable//在构造是如果产生hash冲突那么直接的append到terminal的前面ImmutableMapEntryK, V newEntry (existing null)? new TerminalEntryK, V(key, value): new NonTerminalMapEntryK, V(key, value, existing);table[tableIndex] newEntry;entries[entryIndex] newEntry;checkNoConflictInBucket(key, newEntry, existing);}} 转载于:https://www.cnblogs.com/pona/p/4564256.html
