netflix-hystrix-简例

 1 /** 2 ?* CommandWithFallbackViaNetwork.run模拟远程调用失败，FallbackViaNetwork模拟需要通过网络从Redis获取老数据 3 ?*/ 4 public class CommandWithFallbackViaNetwork extends HystrixCommand<String> { 5 ????private final int id; 6 ?7 ????protected CommandWithFallbackViaNetwork(int id) { 8 ????????//不设置ThreadPoolKey时，ThreadPoolKey默认为groupKey，不同的threadPoolKey代表不同的线程池。 9 ????????//A group name for a HystrixCommand. This is used for grouping together commands such as for reporting, alerting, dashboards or team/library ownership.10 ????????super(Setter.withGroupKey(HystrixCommandGroupKey.Factory.asKey("RemoteServiceX"))11 ????????????????//A key to represent a HystrixCommand for monitoring, circuit-breakers, metrics publishing, caching and other such uses.12 ????????????????.andCommandKey(HystrixCommandKey.Factory.asKey("GetValueCommand"))13 ????????????????.andCommandPropertiesDefaults(HystrixCommandProperties.Setter()14 ????????????????????????.withExecutionIsolationStrategy(HystrixCommandProperties.ExecutionIsolationStrategy.THREAD)));15 ????????this.id = id;16 ????}17 18 ????@Override19 ????protected String run() {20 ????????// ???????remoteServiceXClient.getValue(id);21 ????????//模拟远程调用失败22 ????????throw new RuntimeException("force failure for example");23 ????}24 25 ????@Override26 ????protected String getFallback() {27 ????????return new FallbackViaNetwork(id).execute();28 ????}29 30 ????private static class FallbackViaNetwork extends HystrixCommand<String> {31 ????????private final int id;32 ????????private static Map<Integer, String> memCacheClient = new ConcurrentHashMap<>();//充当Redis缓存，需要访问网络33 34 ????????public FallbackViaNetwork(int id) {35 ????????????//groupKey与CommandWithFallbackViaNetwork一致，36 ????????????super(Setter.withGroupKey(HystrixCommandGroupKey.Factory.asKey("RemoteServiceX"))37 ????????????????????.andCommandKey(HystrixCommandKey.Factory.asKey("GetValueFallbackCommand"))38 ????????????????????// use a different threadpool for the fallback command39 ????????????????????// so saturating the RemoteServiceX pool won‘t prevent40 ????????????????????// fallbacks from executing41 ????????????????????.andThreadPoolKey(HystrixThreadPoolKey.Factory.asKey("RemoteServiceXFallback")));42 ????????????this.id = id;43 ????????}44 45 ????????@Override46 ????????protected String run() {47 ????????????return memCacheClient.get(id);48 ????????}49 50 ????????@Override51 ????????protected String getFallback() {52 ????????????// the fallback also failed53 ????????????// so this fallback-of-a-fallback will54 ????????????// fail silently and return null55 ????????????return null;56 ????????}57 ????}58 }