Question

我有一个Table类，它实现了某种类型对象的ForwardingMultimap。我想知道是否过度创建一个从对象中提取密钥的接口，这样调用者在调用“值”时处理“Entry”对象就不会烦人了。或者让调用者自己放置对象和密钥会更好吗？如果这没关系，创建一个单独的类来处理每个键如下更好，还是调用者自己实现它？

public class CustomObject {
    public String propertyOne;
    public int propertyTwo;

}

public interface ITableAggKey {
    Object getKey(CustomObject customObj);
}

public class Table extends ForwardingMultimap<Object, CustomObject> {
    Multimap m_map;
    public Table(ITableAggKey aggKey){
        m_map = HashMultimap.create();
        m_aggKey = aggKey;
    }
    public boolean put(CustomObject obj) {
        m_map.put(m_aggKey.getKey(obj), obj);
    }
}

public class CustomObjectAggKeys {
    public static final aggKeyOne = new ITableAggKey(){
        @Overide
        public Object getKey(CustomObject obj){
            return obj.propertyOne;
        }
    };

    public static final aggKeyOne = new ITableAggKey(){
        @Overide
        public Object getKey(CustomObject obj){
            return obj.propertyTwo;
        }
    };
}

Answer 1

var searchParams = ['342421111', '77HE2', 'U7IA2'];

async.map(searchParams, function(param, next) {
    Product.find({ UPC: param }).exec(function(err, results) {
        if (err) return next(err);

        if (results.length) return next(null, results);

        vendorProduct.find({ SKU: param }).exec(function(err, results) {
            if (err) return next(err);

            if (results.length) return next(null, results);

            next(null, 'No results');
        });
    });
}, function(err, searchResults) {
    if (err) {
        // handle the error
        return;
    }

    console.log(searchResults);
});

如果你不能使用Java8。添加功能界面。

public class Table<K, T> extends ForwardingMultimap<K, T> {
    Multimap<K, T> m_map;
    Function<T, K> m_aggKey;
    public Table(Function<T, K> aggKey){
        m_map = HashMultimap.create();
        m_aggKey = aggKey;
    }
    public boolean put(T obj) {
        m_map.put(m_aggKey.apply(obj), obj);
    }
}

public static void main(String[] args) {
    Table<String, CustomObject> IndexOne = new Table<>(x -> x.propertyOne);
    Table<Integer, CustomObject> IndexTwo = new Table<>(x -> x.propertyTwo);
}

并且

public interface Function<T, K> {
    K apply(T arg);
}

使用对象和接口从Map的对象获取键

1 个答案: