redis HSCAN命令及jedis的hscan方法[通俗易懂]

全栈程序员-站长 • 2022年10月31日下午3:36 • 未分类 • 阅读 0

参考文档：

http://doc.redisfans.com/key/scan.html

hscan是针对hash类型扫描，如果hash内条目非常多时，比如超过10万，那么根据默认的count = 10，每次扫描返回空的概率很大，此时可以根据情况把count调大：

redis HSCAN命令及jedis的hscan方法[通俗易懂]

下边是对jedis的 hscan进行了封装：

@Override
	public ScanResults hscanToResltByVague(String key, String pattern, String cursor, int pageSize) {
		List<Map.Entry<String, String>> result = null;
		List<Map.Entry<String, String>> results = new ArrayList<Map.Entry<String, String>>();
		ScanResults rsl = new ScanResults();
		ScanParams params = new ScanParams();
		String scanCursor = "0";
		if (!RobotUtils.isNull(cursor)) {
			scanCursor = cursor;
		}
		params.count(pageSize + 50);
		do {
			ScanResult<Entry<String, String>> scanResult = jedis.hscan(key, scanCursor, params.match(pattern));
			scanCursor = scanResult.getStringCursor();
			result = scanResult.getResult();
			results.addAll(result);
			if (results.size() >= pageSize) {
				break;
			}
		} while (!scanCursor.equals("0"));
		rsl.setCursor(scanCursor);
		rsl.setResultsEntry(results);
		rsl.setResultSize(results.size());
		return rsl;
	}

实际使用：

@Test
     public void testRedisHscan() throws InterruptedException {
         
         Thread.sleep(1000*40);
         
         long start = System.currentTimeMillis();
         
         DataCache cache = DataCacheFactory.getInstance();
         //ScanResults rs = cache.hscanToResltByVague("METADATA:VDITEMS", "c3ed2101aa56421d9f0eb23e4b719c29*", "0", 50000);
         List<HashMap<String, String>> lst = cache.hscanToResltByVague(SysConfig.getProperty("metadata.cache.vdItem"), "c3ed2101aa56421d9f0eb23e4b719c29*", "0", 50000).getResults();
         
        long end = System.currentTimeMillis();
         
         System.out.println("+++++++++++++++++耗时："+(end-start));
         try {
            System.out.println("+++++++++++++++++耗时："+(end-start)+"     结果："+JSONUtils.serializeObject(lst));
        } catch (IOException e) {
            // TODO Auto-generated catch block
             e.printStackTrace();
        }
     }

发布者：全栈程序员-站长，转载请注明出处：https://javaforall.net/230809.html原文链接：https://javaforall.net