如何创建自定义注释以拆分请求参数并收集返回结果？

Question

我有一个方法params是一个大于50000项的列表; 限于业务逻辑,列表必须小于30000,所以我有一个方法在逻辑之前将这个数组拆分为2d数组

public static final <T> Collection<List<T>> partitionBasedOnSize(List<T> inputList, int size) {
        AtomicInteger counter = new AtomicInteger(0);
        return inputList.stream().collect(Collectors.groupingBy(s -> counter.getAndIncrement() / size)).values();
}

这是我目前的解决方案:

public List<Account> getChildrenList(List<Long> ids) {
        List<Account> childrenList = new ArrayList<>();
        Collection<List<Long>> childrenId2dList = PartitionArray.partitionBasedOnSize(childrenIdsList, 30000);
        for (List<Long> list : childrenId2dList) {
            //this is my business logic: start
            childrenList.addAll(accountRepository.getAccounts(list));
            //this is my business logic: end
        }
        return childrenAccountsList;
}

我想在方法的顶部创建一个注释,而不是许多重复的代码(每次检查和讨厌......)

抱歉我的英文不好,我画了一个图:方法叫做> spite array>业务逻辑>收集所有结果>返回

Answer 1

在我看来，在这种情况下使用注释有点过度设计（您必须编写注释处理器）。您可以轻松地使用泛型和lambda和/或方法引用来实现您的目标。例如：

更新PartitionArray方法如下：

import java.util.ArrayList;
import java.util.Collection;
import java.util.List;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.function.Function;
import java.util.stream.Collectors;

public class PartitionArray {

    private static <T> Collection<List<T>> partitionBasedOnSize(List<T> inputList, int partitionSize) {
        Collection<List<T>> collection = new ArrayList<>();
        int remainingSize = inputList.size();
        int index = 0;
        while (remainingSize > partitionSize) {
            collection.add(inputList.subList(index, index + partitionSize));
            remainingSize -= partitionSize;
            index += partitionSize;
        }
        collection.add(inputList.subList(index, index + remainingSize));
        return collection;
    }

    public static <D, T> List<D> partitionAndDoBusinessFunction(List<T> ids, Function<List<T>, List<D>> businessFunction, int partitionSize) {
        List<D> dataList = new ArrayList<>();
        Collection<List<T>> idListCollection = partitionBasedOnSize(ids, partitionSize);
        for (List<T> idList : idListCollection) {
            dataList.addAll(businessFunction.apply(idList));
        }
        return dataList;
    }
}

AccountService然后只需从您的（使用方法参考）中使用它：

import java.util.List;

public class AccountService {

    private AccountRepository accountRepository;

    public List<Account> getAccounts(List<Long> ids) {
        return PartitionArray.partitionAndDoBusinessFunction(ids, accountRepository::getAccounts, 30000);
    }
}

或者使用 lambda：

import java.util.List;

public class AccountService {

    private AccountRepository accountRepository;

    public List<Account> getAccounts(List<Long> ids) {
        return PartitionArray.partitionAndDoBusinessFunction(ids, idList -> {
            List<Account> accounts = accountRepository.getAccounts(idList);
            // do more business on accounts
            return accounts;
        }, 30000);
    }
}