com.yimidida.shards.strategy.exit.impl.AggregateExitOperation.java Source code

Introduction

Here is the source code for com.yimidida.shards.strategy.exit.impl.AggregateExitOperation.java

Source

/*
 * @(#)AggregateExitOperation.java 2012-8-1 ?10:00:00
 *
 * Copyright (c) 2011-2012 Makersoft.org all rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 *
 */
package com.yimidida.shards.strategy.exit.impl;

import java.math.BigDecimal;
import java.util.Collections;
import java.util.List;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import com.yimidida.shards.strategy.exit.ExitOperation;
import com.yimidida.shards.strategy.exit.ExitOperationUtils;
import com.yimidida.shards.utils.Assert;
import com.yimidida.shards.utils.Lists;

/**
 * 
 */
public class AggregateExitOperation implements ExitOperation {

    private final SupportedAggregations aggregate;

    // private final String fieldName;

    private final Log log = LogFactory.getLog(getClass());

    private enum SupportedAggregations {

        SUM("sum"), MIN("min"), MAX("max");

        private final String aggregate;

        private SupportedAggregations(String s) {
            this.aggregate = s;
        }

        @SuppressWarnings("unused")
        public String getAggregate() {
            return aggregate;
        }

    }

    public AggregateExitOperation(String statementSuffix) {
        Assert.notNull(statementSuffix);

        this.aggregate = SupportedAggregations.valueOf(statementSuffix.toUpperCase());
    }

    @Override
    public List<Object> apply(List<Object> result) {
        if (result.size() == 0) {
            return Lists.newArrayList((Object) 0);
        }

        //      String className = result.get(0).getClass().getName();

        List<Object> nonNullResults = ExitOperationUtils.getNonNullList(result);

        switch (aggregate) {
        case MAX:
            return Collections
                    .<Object>singletonList(Collections.max(ExitOperationUtils.getComparableList(nonNullResults)));
        case MIN:
            return Collections
                    .<Object>singletonList(Collections.min(ExitOperationUtils.getComparableList(nonNullResults)));
        case SUM:
            return Collections.<Object>singletonList(getSum(nonNullResults, null).intValue());
        default:
            log.error("Aggregation Projection is unsupported: " + aggregate);
            throw new UnsupportedOperationException("Aggregation Projection is unsupported: " + aggregate);
        }
    }

    private BigDecimal getSum(List<Object> results, String fieldName) {
        BigDecimal sum = new BigDecimal(0.0);
        for (Object obj : results) {
            Number num = getNumber(obj, fieldName);
            sum = sum.add(new BigDecimal(num.toString()));
        }
        return sum;
    }

    private Number getNumber(Object obj, String fieldName) {
        if (fieldName == null || "".equals(fieldName)) {
            return (Number) obj;
        }
        return (Number) ExitOperationUtils.getPropertyValue(obj, fieldName);
    }

}