import java.util.BitSet;public class BloomFilter {	/* BitSet初始分配2^24个bit */	private static final int DEFAULT_SIZE = 1 << 25;	/* 不同哈希函数的种子，一般应取质数 */	private static final int[] seeds = new int[] { 5, 7, 11, 13, 31, 37, 61 };	private BitSet bits = new BitSet(DEFAULT_SIZE);	/* 哈希函数对象 */	private SimpleHash[] func = new SimpleHash[seeds.length];	public BloomFilter() {		for (int i = 0; i < seeds.length; i++) {			func[i] = new SimpleHash(DEFAULT_SIZE, seeds[i]);		}	}	// 将字符串标记到bits中	public void add(String value) {		for (SimpleHash f : func) {			bits.set(f.hash(value), true);		}	}	// 判断字符串是否已经被bits标记	public boolean contains(String value) {		if (value == null) {			return false;		}		boolean ret = true;		for (SimpleHash f : func) {			ret = ret && bits.get(f.hash(value));		}		return ret;	}	/* 哈希函数类 */	public static class SimpleHash {		private int cap;		private int seed;		public SimpleHash(int cap, int seed) {			this.cap = cap;			this.seed = seed;		}		// hash函数，采用简单的加权和hash		public int hash(String value) {			int result = 0;			int len = value.length();			for (int i = 0; i < len; i++) {				result = seed * result + value.charAt(i);			}			return (cap - 1) & result;		}	}}