Java 8 Java 8可完全未来所有不同的数据类型
我有3个完整的期货,所有3个都返回不同的数据类型 我希望创建一个result对象,它是所有3个函数返回的结果的组合 因此,我当前的工作代码如下所示:Java 8 Java 8可完全未来所有不同的数据类型,java-8,completable-future,Java 8,Completable Future,我有3个完整的期货,所有3个都返回不同的数据类型 我希望创建一个result对象,它是所有3个函数返回的结果的组合 因此,我当前的工作代码如下所示: public ClassD getResultClassD() { ClassD resultClass = new ClassD(); CompletableFuture<ClassA> classAFuture = CompletableFuture.supplyAsync(() -> service.get
public ClassD getResultClassD() {
ClassD resultClass = new ClassD();
CompletableFuture<ClassA> classAFuture = CompletableFuture.supplyAsync(() -> service.getClassA() );
CompletableFuture<ClassB> classBFuture = CompletableFuture.supplyAsync(() -> service.getClassB() );
CompletableFuture<ClassC> classCFuture = CompletableFuture.supplyAsync(() -> service.getClassC() );
CompletableFuture.allOf(classAFuture, classBFuture, classCFuture)
.thenAcceptAsync(it -> {
ClassA classA = classAFuture.join();
if (classA != null) {
resultClass.setClassA(classA);
}
ClassB classB = classBFuture.join();
if (classB != null) {
resultClass.setClassB(classB);
}
ClassC classC = classCFuture.join();
if (classC != null) {
resultClass.setClassC(classC);
}
});
return resultClass;
}
public类d getResultClassD(){
ClassD resultClass=new ClassD();
CompletableFuture classAFuture=CompletableFuture.SupplySync(()->service.getClassA());
CompletableFuture-classBFuture=CompletableFuture.supplyAsync(()->service.getClassB());
CompletableFuture类未来=CompletableFuture.SupplySync(()->service.getClassC());
CompletableFuture.allOf(classAFuture,classBFuture,classCFuture)
.然后同步(it->{
ClassA ClassA=classAFuture.join();
if(classA!=null){
结果setClassA类(classA);
}
ClassB ClassB=classBFuture.join();
if(classB!=null){
结果类setClassB(classB);
}
ClassC=classCFuture.join();
if(classC!=null){
结果setClassC类(classC);
}
});
返回结果类;
}
我的问题是:
allOf
和theacceptsync
,因此此调用将是非阻塞的。我的理解正确吗ClassD
对象是否正确join
或getNow
方法是否合适李>
你的尝试方向正确,但不正确。您的方法
getResultClassD()
返回一个类型为ClassD
的已实例化对象,任意线程将在该对象上调用修改方法,而getResultClassD()的调用方不会注意到。如果修改方法本身不是线程安全的,那么这可能会导致争用条件,而且调用方永远不会知道ClassD
实例何时实际可以使用
正确的解决办法是:
public CompletableFuture<ClassD> getResultClassD() {
CompletableFuture<ClassA> classAFuture
= CompletableFuture.supplyAsync(() -> service.getClassA() );
CompletableFuture<ClassB> classBFuture
= CompletableFuture.supplyAsync(() -> service.getClassB() );
CompletableFuture<ClassC> classCFuture
= CompletableFuture.supplyAsync(() -> service.getClassC() );
return CompletableFuture.allOf(classAFuture, classBFuture, classCFuture)
.thenApplyAsync(dummy -> {
ClassD resultClass = new ClassD();
ClassA classA = classAFuture.join();
if (classA != null) {
resultClass.setClassA(classA);
}
ClassB classB = classBFuture.join();
if (classB != null) {
resultClass.setClassB(classB);
}
ClassC classC = classCFuture.join();
if (classC != null) {
resultClass.setClassC(classC);
}
return resultClass;
});
}
public CompletableFuture getResultClassD(){
完整的未来类别未来
=CompletableFuture.SupplySync(()->service.getClassA());
完全未来类未来
=CompletableFuture.SupplySync(()->service.getClassB());
完全未来类未来
=CompletableFuture.SupplySync(()->service.getClassC());
返回CompletableFuture.allOf(classAFuture,classBFuture,classCFuture)
.然后应用同步(虚拟->{
ClassD resultClass=new ClassD();
ClassA ClassA=classAFuture.join();
if(classA!=null){
结果setClassA类(classA);
}
ClassB ClassB=classBFuture.join();
if(classB!=null){
结果类setClassB(classB);
}
ClassC=classCFuture.join();
if(classC!=null){
结果setClassC类(classC);
}
返回结果类;
});
}
现在,操作完成后,getResultClassD()
的调用方可以使用返回的CompletableFuture
查询进度状态或链相关操作,或者使用join()
检索结果
要解决其他问题,是的,此操作是异步的,在lambda表达式中使用join()
join
的创建正是因为Future.get()
请注意,null
测试只有在这些service.getClassX()
实际返回null
时才有用。如果其中一个服务调用因异常而失败,则整个操作(由CompletableFuture
表示)将异常完成。我的方法与@Holger在其回答中所做的类似,但将服务调用包装为可选的,这将导致在ThenApplySync阶段生成更干净的代码
CompletableFuture<Optional<ClassA>> classAFuture
= CompletableFuture.supplyAsync(() -> Optional.ofNullable(service.getClassA())));
CompletableFuture<Optional<ClassB>> classBFuture
= CompletableFuture.supplyAsync(() -> Optional.ofNullable(service.getClassB()));
CompletableFuture<Optional<ClassC>> classCFuture
= CompletableFuture.supplyAsync(() -> Optional.ofNullable(service.getClassC()));
return CompletableFuture.allOf(classAFuture, classBFuture, classCFuture)
.thenApplyAsync(dummy -> {
ClassD resultClass = new ClassD();
classAFuture.join().ifPresent(resultClass::setClassA)
classBFuture.join().ifPresent(resultClass::setClassB)
classCFuture.join().ifPresent(resultClass::setClassC)
return resultClass;
});
CompletableFuture类未来
=CompletableFuture.SupplySync(()->可选.ofNullable(service.getClassA());
完全未来类未来
=CompletableFuture.SupplySync(()->可选.ofNullable(service.getClassB());
完全未来类未来
=CompletableFuture.supplyAsync(()->Optional.ofNullable(service.getClassC());
返回CompletableFuture.allOf(classAFuture,classBFuture,classCFuture)
.然后应用同步(虚拟->{
ClassD resultClass=new ClassD();
classAFuture.join().ifPresent(resultClass::setClassA)
classBFuture.join().ifPresent(resultClass::setClassB)
classCFuture.join().ifPresent(resultClass::setClassC)
返回结果类;
});
如果您不想声明那么多的变量,另一种处理方法是使用Combine或CombineAsync将您的未来链接在一起
public CompletableFuture<ClassD> getResultClassD()
{
return CompletableFuture.supplyAsync(ClassD::new)
.thenCombine(CompletableFuture.supplyAsync(service::getClassA), (d, a) -> {
d.setClassA(a);
return d;
})
.thenCombine(CompletableFuture.supplyAsync(service::getClassB), (d, b) -> {
d.setClassB(b);
return d;
})
.thenCombine(CompletableFuture.supplyAsync(service::getClassC), (d, c) -> {
d.setClassC(c);
return d;
});
}
public CompletableFuture getResultClassD()
{
返回CompletableFuture.SupplySync(ClassD::new)
.thenCombine(CompletableFuture.SupplySync(服务::getClassA),(d,a)->{
d、 setClassA(a);
返回d;
})
.thenCombine(CompletableFuture.SupplySync(服务::getClassB),(d,b)->{
d、 setClassB(b);
返回d;
})
.thenCombine(CompletableFuture.supplyAsync(服务::getClassC),(d,c)->{
d、 SETC(c);
返回d;
});
}
getter仍将异步启动,结果将被执行
public class CombindFunctionImpl implement CombindFunction {
public ABCData combind (ClassA a, ClassB b, ClassC c) {
return new ABCData(a, b, c);
}
}
public class FutureProvider {
public CompletableFuture<ClassA> retrieveClassA() {
return CompletableFuture.supplyAsync(() -> {
try {
Thread.sleep(1000L);
} catch (InterruptedException e) {
e.printStackTrace();
}
return new ClassA();
});
}
public CompletableFuture<ClassB> retrieveClassB() {
return CompletableFuture.supplyAsync(() -> {
try {
Thread.sleep(2000L);
} catch (InterruptedException e) {
e.printStackTrace();
}
return new ClassB();
});
}
public CompletableFuture<ClassC> retrieveClassC() {
return CompletableFuture.supplyAsync(() -> {
try {
Thread.sleep(3000L);
} catch (InterruptedException e) {
e.printStackTrace();
}
return new ClassC();
});
}
}
public static void main (String[] args){
CompletableFuture<ClassA> classAfuture = futureProvider.retrieveClassA();
CompletableFuture<ClassB> classBfuture = futureProvider.retrieveClassB();
CompletableFuture<ClassC> classCfuture = futureProvider.retrieveClassC();
System.out.println("starting completable futures ...");
long startTime = System.nanoTime();
ABCData ABCData = CompletableFuture.allOf(classAfuture, classBfuture, classCfuture)
.thenApplyAsync(ignored ->
combineFunction.combind(
classAfuture.join(),
classBfuture.join(),
classCfuture.join())
).join();
long endTime = System.nanoTime();
long duration = (endTime - startTime);
System.out.println("completable futures are complete...");
System.out.println("duration:\t" + Duration.ofNanos(duration).toString());
System.out.println("result:\t" + ABCData);
}