springcloud服务熔断其实就是处理请求超时的方法。
低级版本（无容错实现）
实现服务熔断（Future）
private final ExecutorService executorService = Executors.newSingleThreadExecutor();
/**
* 简易版本
*
* @param message
* @return
* @throws InterruptedException
*/
@GetMapping("/say2")
public String say2(@RequestParam String message) throws Exception {
Future<String> future = executorService.submit(() -> {
return doSay2(message);
});
// 100 毫秒超时
String returnValue = future.get(100, TimeUnit.MILLISECONDS);
return returnValue;
}
低级版本+（带容错实现）
private final ExecutorService executorService = Executors.newSingleThreadExecutor();
/**
* 简易版本
*
* @param message
* @return
* @throws InterruptedException
*/
@GetMapping("/say2")
public String say2(@RequestParam String message) throws Exception {
Future<String> future = executorService.submit(() -> {
return doSay2(message);
});
// 100 毫秒超时
String returnValue = null;
try {
returnValue = future.get(100, TimeUnit.MILLISECONDS);
} catch (InterruptedException | ExecutionException | TimeoutException e) {
// 超级容错 = 执行错误 或 超时
returnValue = errorContent(message);
}
return returnValue;
}
中级版本
/**
* 中级版本
*
* @param message
* @return
* @throws InterruptedException
*/
@GetMapping("/middle/say")
public String middleSay(@RequestParam String message) throws Exception {
Future<String> future = executorService.submit(() -> {
return doSay2(message);
});
// 100 毫秒超时
String returnValue = null;
try {
returnValue = future.get(100, TimeUnit.MILLISECONDS);
} catch (TimeoutException e) {
future.cancel(true); // 取消执行
throw e;
}
return returnValue;
}
增加对异常处理的方法
@RestControllerAdvice(assignableTypes = ServerController.class)
public class CircuitBreakerControllerAdvice {
@ExceptionHandler
public void onTimeoutException(TimeoutException timeoutException,
Writer writer) throws IOException {
writer.write(errorContent("")); // 网络 I/O 被容器
writer.flush();
writer.close();
}
public String errorContent(String message) {
return "Fault";
}
}
高级版本（无注解实现）
/**
* 高级版本
*
* @param message
* @return
* @throws InterruptedException
*/
@GetMapping("/advanced/say")
public String advancedSay(@RequestParam String message) throws Exception {
return doSay2(message);
}
@Aspect
@Component
public class ServerControllerAspect {
private ExecutorService executorService = newFixedThreadPool(20);
@Around("execution(* com.gupao.micro.services.spring.cloud." +
"server.controller.ServerController.advancedSay(..)) && args(message) ")
public Object advancedSayInTimeout(ProceedingJoinPoint point, String message) throws Throwable {
Future<Object> future = executorService.submit(() -> {
Object returnValue = null;
try {
returnValue = point.proceed(new Object[]{message});
} catch (Throwable ex) {
}
return returnValue;
});
Object returnValue = null;
try {
returnValue = future.get(100, TimeUnit.MILLISECONDS);
} catch (TimeoutException e) {
future.cancel(true); // 取消执行
returnValue = errorContent("");
}
return returnValue;
}
public String errorContent(String message) {
return "Fault";
}
@PreDestroy
public void destroy() {
executorService.shutdown();
}
}
高级版本（带注解实现）
抽离代码
private Object doInvoke(ProceedingJoinPoint point,
String message, long timeout) throws Throwable {
Future<Object> future = executorService.submit(() -> {
Object returnValue = null;
try {
returnValue = point.proceed(new Object[]{message});
} catch (Throwable ex) {
}
return returnValue;
});
Object returnValue = null;
try {
returnValue = future.get(timeout, TimeUnit.MILLISECONDS);
} catch (TimeoutException e) {
future.cancel(true); // 取消执行
returnValue = errorContent("");
}
return returnValue;
}
Aspect 注解实现
@Around("execution(* com.gupao.micro.services.spring.cloud." +
"server.controller.ServerController.advancedSay2(..)) && args(message) && @annotation(circuitBreaker)")
public Object advancedSay2InTimeout(ProceedingJoinPoint point,
String message,
CircuitBreaker circuitBreaker) throws Throwable {
long timeout = circuitBreaker.timeout();
return doInvoke(point, message, timeout);
}
反射API 实现
@Around("execution(* com.gupao.micro.services.spring.cloud." +
"server.controller.ServerController.advancedSay2(..)) && args(message) ")
public Object advancedSay2InTimeout(ProceedingJoinPoint point,
String message) throws Throwable {
long timeout = -1;
if (point instanceof MethodInvocationProceedingJoinPoint) {
MethodInvocationProceedingJoinPoint methodPoint = (MethodInvocationProceedingJoinPoint) point;
MethodSignature signature = (MethodSignature) methodPoint.getSignature();
Method method = signature.getMethod();
CircuitBreaker circuitBreaker = method.getAnnotation(CircuitBreaker.class);
timeout = circuitBreaker.timeout();
}
return doInvoke(point, message, timeout);
}
高级版本（信号灯实现 = 单机版限流方案）
@Around("execution(* com.gupao.micro.services.spring.cloud." +
"server.controller.ServerController.advancedSay3(..))" +
" && args(message)" +
" && @annotation(circuitBreaker) ")
public Object advancedSay3InSemaphore(ProceedingJoinPoint point,
String message,
SemaphoreCircuitBreaker circuitBreaker) throws Throwable {
int value = circuitBreaker.value();
if (semaphore == null) {
semaphore = new Semaphore(value);
}
Object returnValue = null;
try {
if (semaphore.tryAcquire()) {
returnValue = point.proceed(new Object[]{message});
Thread.sleep(1000);
} else {
returnValue = errorContent("");
}
} finally {
semaphore.release();
}
return returnValue;
}