package com.fandf.test.redis;

import java.util.BitSet;

/**
 * java布隆過濾器
 *
 * @author fandongfeng
 */
public class MyBloomFilter {

    /**
     * 位數(shù)組大小
     */
    private static final int DEFAULT_SIZE = 2 << 24;

    /**
     * 通過這個數(shù)組創(chuàng)建多個Hash函數(shù)
     */
    private static final int[] SEEDS = new int[]{4, 8, 16, 32, 64, 128, 256};

    /**
     * 初始化位數(shù)組，數(shù)組中的元素只能是 0 或者 1
     */
    private final BitSet bits = new BitSet(DEFAULT_SIZE);

    /**
     * Hash函數(shù)數(shù)組
     */
    private final MyHash[] myHashes = new MyHash[SEEDS.length];

    /**
     * 初始化多個包含 Hash 函數(shù)的類數(shù)組，每個類中的 Hash 函數(shù)都不一樣
     */
    public MyBloomFilter() {
        // 初始化多個不同的 Hash 函數(shù)
        for (int i = 0; i < SEEDS.length; i++) {
            myHashes[i] = new MyHash(DEFAULT_SIZE, SEEDS[i]);
        }
    }

    /**
     * 添加元素到位數(shù)組
     */
    public void add(Object value) {
        for (MyHash myHash : myHashes) {
            bits.set(myHash.hash(value), true);
        }
    }

    /**
     * 判斷指定元素是否存在于位數(shù)組
     */
    public boolean contains(Object value) {
        boolean result = true;
        for (MyHash myHash : myHashes) {
            result = result && bits.get(myHash.hash(value));
        }
        return result;
    }

    /**
     * 自定義 Hash 函數(shù)
     */
    private class MyHash {
        private int cap;
        private int seed;

        MyHash(int cap, int seed) {
            this.cap = cap;
            this.seed = seed;
        }

        /**
         * 計算 Hash 值
         */
        int hash(Object obj) {
            return (obj == null) ? 0 : Math.abs(seed * (cap - 1) & (obj.hashCode() ^ (obj.hashCode() >>> 16)));
        }
    }

    public static void main(String[] args) {
        String str = "好好學技術(shù)";
        MyBloomFilter myBloomFilter = new MyBloomFilter();
        System.out.println("str是否存在：" + myBloomFilter.contains(str));
        myBloomFilter.add(str);
        System.out.println("str是否存在：" + myBloomFilter.contains(str));
    }


}

<dependency>
    <groupId>com.google.guava</groupId>
    <artifactId>guava</artifactId>
    <version>31.1-jre</version>
</dependency>

package com.fandf.test.redis;

import com.google.common.base.Charsets;
import com.google.common.hash.BloomFilter;
import com.google.common.hash.Funnels;

/**
 * @author fandongfeng
 */
public class GuavaBloomFilter {

    public static void main(String[] args) {
        BloomFilter<String> bloomFilter = BloomFilter.create(Funnels.stringFunnel(Charsets.UTF_8),100000,0.01);
        bloomFilter.put("好好學技術(shù)");
        System.out.println(bloomFilter.mightContain("不好好學技術(shù)"));
        System.out.println(bloomFilter.mightContain("好好學技術(shù)"));
    }
}

<dependency>
    <groupId>cn.hutool</groupId>
    <artifactId>hutool-all</artifactId>
    <version>5.8.3</version>
</dependency>

package com.fandf.test.redis;

import cn.hutool.bloomfilter.BitMapBloomFilter;
import cn.hutool.bloomfilter.BloomFilterUtil;

/**
 * @author fandongfeng
 */
public class HutoolBloomFilter {
    public static void main(String[] args) {
        BitMapBloomFilter bloomFilter = BloomFilterUtil.createBitMap(1000);
        bloomFilter.add("好好學技術(shù)");
        System.out.println(bloomFilter.contains("不好好學技術(shù)"));
        System.out.println(bloomFilter.contains("好好學技術(shù)"));
    }

}

<dependency>
    <groupId>org.redisson</groupId>
    <artifactId>redisson</artifactId>
    <version>3.20.0</version>
</dependency>

package com.fandf.test.redis;
 
import org.redisson.Redisson;
import org.redisson.api.RBloomFilter;
import org.redisson.api.RedissonClient;
import org.redisson.config.Config;
 
/**
 * Redisson 實現(xiàn)布隆過濾器
 * @author fandongfeng
 */
public class RedissonBloomFilter {
 
    public static void main(String[] args) {
        Config config = new Config();
        config.useSingleServer().setAddress("redis://127.0.0.1:6379");
        //構(gòu)造Redisson
        RedissonClient redisson = Redisson.create(config);
 
        RBloomFilter<String> bloomFilter = redisson.getBloomFilter("name");
        //初始化布隆過濾器：預計元素為100000000L,誤差率為1%
        bloomFilter.tryInit(100000000L,0.01);
        bloomFilter.add("好好學技術(shù)");
 
        System.out.println(bloomFilter.contains("不好好學技術(shù)"));
        System.out.println(bloomFilter.contains("好好學技術(shù)"));
    }
}