社区网站7.4 Redis高级数据类型

  HyperLogLog
（1）采用一种基数算法，用于完成独立总数的统计。
（2）占据空间小，无论统计多少个数据，只占12k的内存空间。
（3）不精确的统计算法，标准误差为0.81%。
  Bitmap
（1）不是一种独立的数据结构，实际上就是字符串。
（2）支持按位存取数据，可以将其看成是byte数组。
（3）适合存储索大量的连续的数据的布尔值。

//统计20万个重复数据的独立总数
    @Test
    public void testHyperLogLog(){
        String redisKey = "test:hll:01";

        for(int i=1;i<=100000;i++){
            redisTemplate.opsForHyperLogLog().add(redisKey,i);
        }

        for(int i=1;i<=100000;i++){
            int r = (int) (Math.random()*100000+1);
            redisTemplate.opsForHyperLogLog().add(redisKey,r);
        }

        long size = redisTemplate.opsForHyperLogLog().size(redisKey);
        System.out.println(size);
    }

// 将3组数据合并，再统计合并后的重复数据的独立总数
    @Test
    public void testHyperLogLogUnion(){
        String redisKey2 = "test:hll:02";
        for(int i=1;i<=10000;i++){
            redisTemplate.opsForHyperLogLog().add(redisKey2,i);
        }

        String redisKey3 = "test:hll:03";
        for(int i=5001;i<=15000;i++){
            redisTemplate.opsForHyperLogLog().add(redisKey3,i);
        }

        String redisKey4 = "test:hll:04";
        for(int i=10001;i<=20000;i++){
            redisTemplate.opsForHyperLogLog().add(redisKey4,i);
        }

        String unionKey = "test:hll:union";
        redisTemplate.opsForHyperLogLog().union(unionKey,redisKey2,redisKey3,redisKey4);

        long size = redisTemplate.opsForHyperLogLog().size(unionKey);
        System.out.println(size);
    }

// 统计一组数据的布尔值（比如全班签到次数）
    @Test
    public void testBitMap(){
        String redisKey = "test:bmp:01";
        redisTemplate.opsForValue().setBit(redisKey,1,true);
        redisTemplate.opsForValue().setBit(redisKey,4,true);
        redisTemplate.opsForValue().setBit(redisKey,7,true);

        //查询
        System.out.println(redisTemplate.opsForValue().getBit(redisKey,0));
        System.out.println(redisTemplate.opsForValue().getBit(redisKey,1));
        System.out.println(redisTemplate.opsForValue().getBit(redisKey,2));

        //统计
        Object obj = redisTemplate.execute(new RedisCallback() { //回调接口，匿名实现
            @Override
            public Object doInRedis(RedisConnection connection) throws DataAccessException {
                return connection.bitCount(redisKey.getBytes()); //统计这组Bytes里1的个数
            }
        });
        System.out.println(obj);
    }

//统计3组数据(比如3天)的布尔值，并对这3组数据做OR运算
    @Test
    public void testBitMapOperation(){
        String redisKey2 = "test:bm:02";
        redisTemplate.opsForValue().setBit(redisKey2,0,true);
        redisTemplate.opsForValue().setBit(redisKey2,1,true);
        redisTemplate.opsForValue().setBit(redisKey2,2,true);

        String redisKey3 = "test:bm:02";
        redisTemplate.opsForValue().setBit(redisKey3,2,true);
        redisTemplate.opsForValue().setBit(redisKey3,3,true);
        redisTemplate.opsForValue().setBit(redisKey3,4,true);

        String redisKey4 = "test:bm:02";
        redisTemplate.opsForValue().setBit(redisKey4,4,true);
        redisTemplate.opsForValue().setBit(redisKey4,5,true);
        redisTemplate.opsForValue().setBit(redisKey4,6,true);

        String redisKey = "test:bm:or";
        Object obj = redisTemplate.execute(new RedisCallback() {
            @Override
            public Object doInRedis(RedisConnection connection) throws DataAccessException {
                connection.bitOp(RedisStringCommands.BitOperation.OR,
                        redisKey.getBytes(),redisKey2.getBytes(),redisKey3.getBytes(),redisKey4.getBytes());
                return connection.bitCount(redisKey.getBytes());
            }
        });
        System.out.println(obj);

        System.out.println(redisTemplate.opsForValue().getBit(redisKey,0));
        System.out.println(redisTemplate.opsForValue().getBit(redisKey,1));
        System.out.println(redisTemplate.opsForValue().getBit(redisKey,2));
        System.out.println(redisTemplate.opsForValue().getBit(redisKey,3));
        System.out.println(redisTemplate.opsForValue().getBit(redisKey,4));
        System.out.println(redisTemplate.opsForValue().getBit(redisKey,5));
        System.out.println(redisTemplate.opsForValue().getBit(redisKey,6));
    }