HashMap 反序列化：从流中重建 HashMap 实例

/** Reconstitute the {@code HashMap} instance from a stream (i.e., deserialize it). */ private void readObject(java.io.ObjectInputStream s) throws IOException, ClassNotFoundException { // Read in the threshold (ignored), loadfactor, and any hidden stuff s.defaultReadObject(); reinitialize(); if (loadFactor <= 0 || Float.isNaN(loadFactor)) { throw new InvalidObjectException('Illegal load factor: ' + loadFactor); } s.readInt(); // Read and ignore number of buckets int mappings = s.readInt(); // Read number of mappings (size) if (mappings < 0) { throw new InvalidObjectException('Illegal mappings count: ' + mappings); } else if (mappings > 0) { // (if zero, use defaults) // Size the table using given load factor only if within // range of 0.25...4.0 float lf = Math.min(Math.max(0.25f, loadFactor), 4.0f); float fc = (float) mappings / lf + 1.0f; int cap = ((fc < DEFAULT_INITIAL_CAPACITY) ? DEFAULT_INITIAL_CAPACITY : (fc >= MAXIMUM_CAPACITY) ? MAXIMUM_CAPACITY : tableSizeFor((int) fc)); float ft = (float) cap * lf; threshold = ((cap < MAXIMUM_CAPACITY && ft < MAXIMUM_CAPACITY) ? (int) ft : Integer.MAX_VALUE); @SuppressWarnings({ 'rawtypes', 'unchecked' }) Node<K, V>[] tab = (Node<K, V>[]) new Node[cap]; table = tab; // Read the keys and values, and put the mappings in the HashMap for (int i = 0; i < mappings; i++) { @SuppressWarnings('unchecked') K key = (K) s.readObject(); @SuppressWarnings('unchecked') V value = (V) s.readObject(); putVal(hash(key), key, value, false, false); } } }