CompletableFuture的thenCombine结果组合用法实例
CompletableFuture的thenCombine结果组合用法实例
thenCombine 方法，合并两个线程任务的结果，并进一步处理。有种大数的MapReduce的思想。
举例：
@Autowired
@Qualifier(ThreadPoolConfig.IMPORT_EXECUTOR)
private ThreadPoolTaskExecutor threadPoolTaskExecutor;
定义线程池。并在CompletableFuture中指定线程池。也可以不指定线程池，没有指定Executor的方法会使用ForkJoinPool.commonPool() 作为它的线程池执行异步代码。如果指定线程池，则使用指定的线程池运行。
如果所有 CompletableFuture 共享一个线程池，那么一旦有任务执行一些很慢的 I/O 操作，就会导致线程池中所有线程都阻塞在 I/O 操作上，从而造成线程饥饿，进而影响整个系统的性能。所以，建议根据不同的业务类型创建不同的线程池，以避免互相干扰
1. demo
public List<Object> queryRecentOrders(String custNo) {
CompletableFuture<List<Integer>> future1 = CompletableFuture
.supplyAsync(() -> {
int number = 1;
List<Integer> integers = Lists.newArrayList(number);
System.out.println("first:" + integers);
return integers;
}, threadPoolTaskExecutor);
CompletableFuture<List<Integer>> future2 = CompletableFuture
.supplyAsync(new Supplier<List<Integer>>() {
@Override
public List<Integer> get() {
int number = 2;
List<Integer> integers = Lists.newArrayList(number);
System.out.println("second:" + integers);
return integers;
}
}, threadPoolTaskExecutor);
CompletableFuture<List<Integer>> future3 = CompletableFuture
.supplyAsync(new Supplier<List<Integer>>() {
@Override
public List<Integer> get() {
int number = 3;
List<Integer> integers = Lists.newArrayList(number);
System.out.println("third:" + integers);
return integers;
}
}, threadPoolTaskExecutor);
CompletableFuture<Integer> result = future1
.thenCombine(future2, (x, y) -> {
System.err.println("x:" + x);
System.err.println("y:" + y);
Integer sum = Lists.newArrayList(x, y).stream().flatMap(k -> k.stream()).reduce(0, Integer::sum);
return sum;
}).thenCombine(future3, (x, y) -> {
System.err.println("x:" + x);
System.err.println("y:" + y);
y.add(x);
Integer reduce = y.stream().reduce(0, Integer::sum);
return reduce;
});
try {
Integer integer = result.get();
System.err.println(integer+"-----------------");
} catch (InterruptedException e) {
e.printStackTrace();
} catch (ExecutionException e) {
e.printStackTrace();
}
return null;
}
2. 实例
/**
* 加速卡
* 自营会员
* 拿钱卡
* 车主卡
* 省钱卡
* Vplus
* 全能
*/
public List<RightOrderDto> queryRecentOrders(String custNo) {
Date beforeDate = DateUtil.offsetDay(DateUtil.beginOfDay(new Date()), -7);
//加速卡
CompletableFuture<List<RightOrderDto>> future1 = CompletableFuture
.supplyAsync(() -> {
List<TQuickenCardOrder> tCuserLoanRightOrders = cbsQuickenCardService.queryRecentOrders(custNo, beforeDate);
List<RightOrderDto> collect = tCuserLoanRightOrders.stream().filter(Objects::nonNull).map(k -> {
RightOrderDto orderDto = RightOrderDto.builder()
.orderId(k.getId()).orderName(k.getOrderName())
.createDatetime(k.getCreateDatetime()).businessType(ComplaintBusinessType.QUICKEN_CARD.getCode())
.build();
return orderDto;
}).collect(Collectors.toList());
return collect;
}, threadPoolTaskExecutor);
//自营
CompletableFuture<List<RightOrderDto>> future2 = CompletableFuture
.supplyAsync(() -> {
List<VipOwnOrderResponse> xsqyOrders = cbsVipUserOwnService.queryRecentOrders(custNo, beforeDate);
List<RightOrderDto> collect = xsqyOrders.stream().filter(Objects::nonNull).map(k -> {
RightOrderDto orderDto = RightOrderDto.builder()
.orderId(k.getId()).orderName(k.getOrderName())
.createDatetime(k.getCreateDatetime()).businessType(ComplaintBusinessType.SELFSUPPORT.getCode())
.build();
return orderDto;
}).collect(Collectors.toList());
return collect;
}, threadPoolTaskExecutor);
//拿钱卡
CompletableFuture<List<RightOrderDto>> future3 = CompletableFuture
.supplyAsync(() -> {
List<GetMoneyCardOrderOmsResp> tCuserLoanRightOrders = cbsGetMoneyCardService.queryRecentOrders(custNo, beforeDate);
List<RightOrderDto> collect = tCuserLoanRightOrders.stream().filter(Objects::nonNull).map(k -> {
RightOrderDto orderDto = RightOrderDto.builder()
.orderId(k.getId()).orderName(k.getCardName())
.createDatetime(k.getCreateDatetime()).businessType(ComplaintBusinessType.GET_MONEY.getCode())
.build();
return orderDto;
}).collect(Collectors.toList());
return collect;
}, threadPoolTaskExecutor);
/**
* 省钱卡 merchant_no in ('指北','橡树')
* 车主卡 merchant_no = '车主'
*/
List<String> sqk = Lists.newArrayList(MerchantNoEnum.XIANGSHU.getCode(), MerchantNoEnum.ZHIBEI.getCode());
List<String> czk = Lists.newArrayList(MerchantNoEnum.CHEZHU.getCode());
CompletableFuture<List<RightOrderDto>> future4 = CompletableFuture
.supplyAsync(() -> {
List<TSaveMoneyCardOrder> tCuserLoanRightOrders = cbsSaveMoneyCardService.queryRecentOrders(custNo, beforeDate);
List<RightOrderDto> collect = tCuserLoanRightOrders.stream().filter(Objects::nonNull).map(k -> {
String orderName = null;
String businessType = null;
if (sqk.contains(k.getMerchantNo())) {
orderName = "省钱卡";
businessType = ComplaintBusinessType.SAVEMONEYCARD.getCode();
}
if (czk.contains(k.getMerchantNo())) {
orderName = "车主卡";
businessType = ComplaintBusinessType.CARCARD.getCode();
}
RightOrderDto orderDto = RightOrderDto.builder()
.orderId(k.getOrderNo()).orderName(orderName)
.createDatetime(k.getCreateDatetime()).businessType(businessType)
.build();
return orderDto;
}).collect(Collectors.toList());
return collect;
}, threadPoolTaskExecutor);
//vplus 和 全能
CompletableFuture<List<RightOrderDto>> future5 = CompletableFuture
.supplyAsync(() -> {
List<TCardOrder> xsqyOrders = tCardOrderService.queryRecentOrders(custNo, beforeDate);
List<RightOrderDto> collect = xsqyOrders.stream().filter(Objects::nonNull).map(k -> {
String businessType = null;
if ("Vplus".equals(k.getProductType())) {
businessType = ComplaintBusinessType.VPLUS.getCode();
}
if ("qnk".equals(k.getProductType())) {
businessType = ComplaintBusinessType.QNK.getCode();
}
RightOrderDto orderDto = RightOrderDto.builder()
.orderId(k.getOrderNo()).orderName(k.getOrderName())
.createDatetime(k.getCreateDatetime()).businessType(businessType)
.build();
return orderDto;
}).collect(Collectors.toList());
return collect;
}, threadPoolTaskExecutor);
CompletableFuture<List<RightOrderDto>> result = future1
.thenCombine(future2, (x, y) -> Lists.newArrayList(x, y).stream().filter(Objects::nonNull).flatMap(k -> k.stream()).collect(Collectors.toList()))
.thenCombine(future3, (x, y) -> Lists.newArrayList(x, y).stream().filter(Objects::nonNull).flatMap(k -> k.stream()).collect(Collectors.toList()))
.thenCombine(future4, (x, y) -> Lists.newArrayList(x, y).stream().filter(Objects::nonNull).flatMap(k -> k.stream()).collect(Collectors.toList()))
.thenCombine(future5, (x, y) -> Lists.newArrayList(x, y).stream().filter(Objects::nonNull).flatMap(k -> k.stream()).collect(Collectors.toList()));
try {
return result.get();
} catch (Exception e) {
logger.error("custNo:{}执行cbs获取权益卡信息出现异常e:{}", custNo, e);
}
return null;
}
总结
thenCombine 用法，是将任务用多线程分组执行再组合。在项目实战中应用场景还是比较多的。