使用谓词在Hazelcast中搜索键集 [英] Using Predicate to search a keyset in Hazelcast

问题描述

我是Hazelcast的新手-进行评估和原型设计，看它是否适合我们的分布式内存缓存需求. 要求之一是能够使用通配符搜索给定地图中的键.查看IMap文档，看起来可以使用keySet(Predicate predicate).但是我无法弄清楚如何以这样的方式使用谓词:给定通配符字符串，将返回包含所有匹配键的keySet.一个例子会有所帮助.

I'm new to Hazelcast - evaluating and prototyping to see if it fits our distributed memory cache needs. One of the requirements was to be able to use wild cards to search for keys in a given map. Looking through the IMap documentation, looks like keySet(Predicate predicate) can be used. But I couldn't figure how to use the Predicate in such a way that given a wild card string, a keySet is returned containing all keys that match. An example will be helpful.

我的代码段.这是客户端.

A snippet of my code. This is the client side.

IMap<String, String> mapTest1 = client.getMap("testMap");

mapTest1.put( "testKey1", "This is a Test" );
mapTest1.put( "testKey2", "This value has a long key name" );
mapTest1.put( "key3", "Another value" );
// Need a wild card search on the map, such that all keys with "%test%" will be returned.

谢谢.

推荐答案

如果我正确理解了您的请求，这应该可以解决问题:

This should do the trick if I understood your request correctly:

public class Test {

    public static void main(String[] args) {
        HazelcastInstance hazelcastInstance = Hazelcast.newHazelcastInstance();

        IMap<String, String> map = hazelcastInstance.getMap("someMap");
        Collection<String> keys = map.keySet(
            new RegexPredicate("[a-z].*[a-z0-9]"));

        System.out.println(keys);
     }

     public static class RegexPredicate implements Predicate<String, String> {

        private String regex;
        private transient Pattern pattern;

        public RegexPredicate(String regex) {
            this.regex = regex;
        }

        @Override
        public boolean apply(Map.Entry<String, String> mapEntry) {
            if (pattern == null) {
                 pattern = Pattern.compile(regex);
            }
            Matcher matcher = pattern.matcher(mapEntry.getKey());
            return matcher.matches();
        }
    }
}

这篇关于使用谓词在Hazelcast中搜索键集的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！