布隆过滤器的java实现

以下是布隆过滤器的Java实现示例：

1. 使用Java.util包的BitSet类实现布隆过滤器：

import java.util.BitSet;

public class BloomFilter {
    private BitSet bitSet;
    private int size;
    private int[] seeds;

    public BloomFilter(int size, int[] seeds) {
        this.size = size;
        this.seeds = seeds;
        this.bitSet = new BitSet(size);
    }

    public void add(String value) {
        for (int seed : seeds) {
            int hash = getHash(value, seed);
            bitSet.set(hash, true);
        }
    }

    public boolean contains(String value) {
        for (int seed : seeds) {
            int hash = getHash(value, seed);
            if (!bitSet.get(hash)) {
                return false;
            }
        }
        return true;
    }

    private int getHash(String value, int seed) {
        int hash = 0;
        for (char c : value.toCharArray()) {
            hash = seed * hash + c;
        }
        return Math.abs(hash) % size;
    }
}

2. 使用Redis的Bitmap实现布隆过滤器：

import redis.clients.jedis.Jedis;

public class BloomFilter {
    private Jedis jedis;
    private String key;
    private int size;
    private int[] seeds;

    public BloomFilter(String key, int size, int[] seeds) {
        this.key = key;
        this.size = size;
        this.seeds = seeds;
        this.jedis = new Jedis("localhost");
    }

    public void add(String value) {
        for (int seed : seeds) {
            int hash = getHash(value, seed);
            jedis.setbit(key, hash, true);
        }
    }

    public boolean contains(String value) {
        for (int seed : seeds) {
            int hash = getHash(value, seed);
            if (!jedis.getbit(key, hash)) {
                return false;
            }
        }
        return true;
    }

    private int getHash(String value, int seed) {
        int hash = 0;
        for (char c : value.toCharArray()) {
            hash = seed * hash + c;
        }
        return Math.abs(hash) % size;
    }
}