我正在尝试找出使用 VAVR 的 Try 的惯用方法。
我正在查看的用例必须执行以下步骤:
- 获取鞋子列表(调用可以抛出一个已检查的异常)
- 清洁每只鞋(调用可以抛出一个已检查的异常)
- 恢复每双鞋(调用可以抛出一个已检查的异常)
- 返回清洁/修复鞋子的列表
这是我的示例玩具代码,其中 processRequest 方法购买 n 双鞋,清洁并修复它们;打印错误(如果有):
// definitions
ShoeStore java.util.List<Shoe> buy(int numberOfPairs) throws OutOfStockException;
ShoeCleaningService Shoe clean(Shoe dirtyShoe) throws OutOfShoePolishException;
ShoeRestoreService Shoe restore(Shoe oldShoe) throws OutOfSparePartsException;
class EnterpriseShoeService {
// constructor
...
public List<Shoe> processRequest(int numberOfPairs) {
Try<List<Shoe>> shoes = Try.of(() -> shoeStore.buy(numberOfPairs));
Try<List<Try<Shoe>>> cleanedAndRestoredShoes = shoes.map(xs -> xs.stream().map(shoe ->
Try.success(shoe)
.andThenTry(shoeCleaningService::clean)
.andThenTry(shoeRestoreService::restore))
.collect(Collectors.toList()));
List<Shoe> result = cleanedAndRestoredShoes
.getOrElseGet(err -> {
System.out.println(err.getMessage());
return Collections.emptyList();
})
.stream()
.map(shoeTry -> shoeTry.onFailure(err -> System.out.println(err.getMessage())))
.filter(Try::isSuccess)
.map(Try::get)
.collect(Collectors.toList());
return result;
}
}
我的问题是:如何简化这个逻辑?有没有可以消除的方法调用?能否提高可读性?
最佳答案
我不知道是否一切都按预期工作,因为没有提到要求,但这应该让您了解分解的能力。
import io.vavr.collection.List;
import io.vavr.control.Try;
public class TryListComposition {
ShoeStore store;
ShoeCleaningService cleaningService;
ShoeRestoreService restoreService;
public java.util.List<Shoe> processRequest(int numberOfPairs) {
return processShoesRequest(numberOfPairs).getOrElse(List.empty()).toJavaList();
}
public Try<List<Shoe>> processShoesRequest(int numberOfPairs) {
return this.buy(numberOfPairs)
.map(shoes -> shoes
.map(this::cleanAndRestore)
.flatMap(x -> x)
);
}
public Try<Shoe> cleanAndRestore(Shoe shoe) {
return clean(shoe).flatMap(this::restore);
}
Try<List<Shoe>> buy(int numberOfPairs) {
return Try.of(() ->
List.ofAll(store.buy(numberOfPairs).stream());
}
Try<Shoe> clean(Shoe dirtyShoe) {
return Try.of(() -> cleaningService.clean(dirtyShoe));
}
Try<Shoe> restore(Shoe oldShoe) {
return Try.of(() -> restoreService.restore(oldShoe));
}
}
class Shoe {
}
interface ShoeStore {
java.util.List<Shoe> buy(int numberOfPairs) throws
OutOfStockException;
}
interface ShoeCleaningService {
Shoe clean(Shoe dirtyShoe) throws OutOfShoePolishException;
}
interface ShoeRestoreService {
Shoe restore(Shoe oldShoe) throws OutOfSparePartsException;
}
class OutOfStockException extends Exception {
}
class OutOfShoePolishException extends Exception {
}
class OutOfSparePartsException extends Exception {
}
关于java - VAVR 撰写尝试和列表,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/56068599/