9.Hystrix实践篇

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1.业务降级(在film服务工程中修改)
(1).引入依赖

<dependency>
  <groupId>org.springframework.cloud</groupId>
  <artifactId>spring-cloud-starter-netflix-hystrix</artifactId>
</dependency>

(2).controller层开发
在FilmController类中新增获取电影列表降级方法findFilmListFallback，并在findFilmList方法上添加@HystrixCommand注解，具体代码如下。

@Slf4j
@RestController
@RequestMapping("/films")
public class FilmController {
    //获取电影列表降级方法
    public ServerResponse findFilmListFallback(@RequestBody BasePageVO basePageVO) throws CommonServiceException {
        return ServerResponse.createByErrorCodeMessage(500, "请求处理降级返回");
    }

    //获取电影列表
    @HystrixCommand(fallbackMethod = "findFilmListFallback", commandProperties = {
            @HystrixProperty(name = "execution.isolation.strategy", value = "THREAD"),
            @HystrixProperty(name = "execution.isolation.thread.timeoutInMilliseconds", value = "1000"),
            @HystrixProperty(name = "circuitBreaker.requestVolumeThreshold", value = "10"),
            @HystrixProperty(name = "circuitBreaker.errorThresholdPercentage", value = "50")
    }, threadPoolProperties = {
            @HystrixProperty(name = "coreSize", value = "10"),
            @HystrixProperty(name = "keepAliveTimeMinutes", value = "1000"),
            @HystrixProperty(name = "maxQueueSize", value = "10"),
            @HystrixProperty(name = "queueSizeRejectionThreshold", value = "8"),
            @HystrixProperty(name = "metrics.rollingStats.numBuckets", value = "12"),
            @HystrixProperty(name = "metrics.rollingStats.timeInMilliseconds", value = "1500")
    })
    @RequestMapping(value = "/findFilmList", method = RequestMethod.POST)
    public ServerResponse findFilmList(@RequestBody BasePageVO basePageVO) throws CommonServiceException {
        //检查入参
        basePageVO.checkParam();
        if (basePageVO.getPageSize() > 1000) {
            //业务执行出现异常，触发fallback
            throw new CommonServiceException(500, "pageSIze太大");
        }

        //调用逻辑层，获取返回参数
        IPage<Film> results = filmService.findFilmList(basePageVO.getCurrentPage(), basePageVO.getPageSize());

        return ServerResponse.createBySuccess(PageUtil.getPageResult(results));
    }
}

(3).启动项目
在启动类MoviesFilmApplication上新增注解@EnableHystrix，然后启动项目。

@MapperScan(basePackages = {"com.steven.movies.film.dao"})
@EnableHystrix
@EnableDiscoveryClient
@SpringBootApplication
public class MoviesFilmApplication {

    public static void main(String[] args) {
        SpringApplication.run(MoviesFilmApplication.class, args);
    }

}

(4).测试

启动项目，然后在postman中请求“localhost:8080/movies/film-api/films/findFilmList”，可以查询到相应的信息，测试结果如下图所示。

9.Hystrix实践篇_hystrix

(5).业务异常
业务执行异常，希望通过CommonServiceException抛出异常信息，而不是进入降级处理，解决方法是在@HystrixCommand注解里增加ignoreExceptions属性。

@Slf4j
@RestController
@RequestMapping("/films")
public class FilmController {
    //获取电影列表降级方法
    public ServerResponse findFilmListFallback(@RequestBody BasePageVO basePageVO) throws CommonServiceException {
        return ServerResponse.createByErrorCodeMessage(500, "请求处理降级返回");
    }

    //获取电影列表
    @HystrixCommand(fallbackMethod = "findFilmListFallback", commandProperties = {
            @HystrixProperty(name = "execution.isolation.strategy", value = "THREAD"),
            @HystrixProperty(name = "execution.isolation.thread.timeoutInMilliseconds", value = "1000"),
            @HystrixProperty(name = "circuitBreaker.requestVolumeThreshold", value = "10"),
            @HystrixProperty(name = "circuitBreaker.errorThresholdPercentage", value = "50")
    }, threadPoolProperties = {
            @HystrixProperty(name = "coreSize", value = "10"),
            @HystrixProperty(name = "keepAliveTimeMinutes", value = "1000"),
            @HystrixProperty(name = "maxQueueSize", value = "10"),
            @HystrixProperty(name = "queueSizeRejectionThreshold", value = "8"),
            @HystrixProperty(name = "metrics.rollingStats.numBuckets", value = "12"),
            @HystrixProperty(name = "metrics.rollingStats.timeInMilliseconds", value = "1500")
    }, ignoreExceptions = {CommonServiceException.class})
    @RequestMapping(value = "/findFilmList", method = RequestMethod.POST)
    public ServerResponse findFilmList(@RequestBody BasePageVO basePageVO) throws CommonServiceException {
        //检查入参
        basePageVO.checkParam();
        if (basePageVO.getPageSize() > 1000) {
            //业务执行出现异常，触发fallback
            throw new CommonServiceException(500, "pageSIze太大");
        }

        //调用逻辑层，获取返回参数
        IPage<Film> results = filmService.findFilmList(basePageVO.getCurrentPage(), basePageVO.getPageSize());

        return ServerResponse.createBySuccess(PageUtil.getPageResult(results));
    }
}

启动项目，然后在postman中请求“localhost:8080/movies/film-api/films/findFilmList”，可以查询到相应的信息，测试结果如下图所示。

9.Hystrix实践篇_面试_02

2.Feign整合Hystrix(在hall服务工程中修改)
(1).依赖
Feign中包含了Hystrix，因此不需要引入依赖。

(2).引入配置

feign:
  hystrix:
    enabled: true

(3).Fallback开发
在feign目录下新建FilmFeignFallbackAPIImpl类，具体代码如下。

@Slf4j
@Service
public class FilmFeignFallbackAPIImpl implements FilmFeignAPI {
    @Override
    public ServerResponse findFilmListByHallId(Integer hallId) {
        log.error("请求处理降级返回");
        return ServerResponse.createByErrorCodeMessage(500, "请求处理降级返回");
    }
}

在@FeignClient注解上添加fallback属性。

@FeignClient(name = "film.service", path = "/films",fallback = FilmFeignFallbackAPIImpl.class)
public interface FilmFeignAPI extends BaseFeignAPI {
    //根据影厅id获取电影信息
    @RequestMapping(value = "/findFilmListByHallId/{hallId}", method = RequestMethod.GET)
    ServerResponse findFilmListByHallId(@PathVariable("hallId") Integer hallId);
}

(4).测试

不启动电影服务，模拟电影服务不可用触发fallback的场景，启动影厅服务，然后在postman中请求“localhost:8080/movies/hall-api/halls/findFilmListByHallIds”，可以查询到相应的信息，测试结果如下图所示。

9.Hystrix实践篇_面试_03


9.Hystrix实践篇_面试_04


由上图可知，影厅服务调用电影服务失败，触发fallback，一共触发6次。(5).hall服务工程目录结构

9.Hystrix实践篇_状态码_05

4.Zuul整合Hystrix(在zuul和film服务工程中修改)
(1).引入配置

hystrix:
  command:
    default:
      execution:
        isolation:
          thread:
            timoutInMilliseconds: 1000

(2).fallback开发
首先在项目目录“/src/main/java/com/steven/movies/zuul”下新建“/fallback”目录，并在fallback目录下新建FilmProviderFallback和HallProviderFallback类，具体代码如下。

@Slf4j
@Component
public class FilmProviderFallback implements FallbackProvider {
    @Override
    public String getRoute() {
        return "film.service";
    }

    @Override
    public ClientHttpResponse fallbackResponse(String route, Throwable cause) {
        return new ClientHttpResponse() {
            //ClientHttpResponse的fallback状态码，返回HttpStatus
            @NonNull
            @Override
            public HttpStatus getStatusCode() {
                return HttpStatus.INTERNAL_SERVER_ERROR;
            }

            //ClientHttpResponse的fallback状态码，返回int
            @Override
            public int getRawStatusCode() {
                return this.getStatusCode().value();
            }

            //ClientHttpResponse的fallback状态码，返回String
            @NonNull
            @Override
            public String getStatusText() {
                return this.getStatusCode().getReasonPhrase();
            }

            //回收资源方法，用于回收当前fallback逻辑开启的资源对象
            @Override
            public void close() {

            }

            //设置方法体，Zuul会将本方法返回的输入流数据读取，并且通过HttpServletResponse的输出流输出到客户端
            @NonNull
            @Override
            public InputStream getBody() {
                log.error("zuul time:{}",System.currentTimeMillis());
                String result = "电影服务不可用";
                return new ByteArrayInputStream(result.getBytes(StandardCharsets.UTF_8));
            }

            //设置响应头
            @NonNull
            @Override
            public HttpHeaders getHeaders() {
                HttpHeaders httpHeaders = new HttpHeaders();
                httpHeaders.setContentType(new MediaType("application", "json", StandardCharsets.UTF_8));
                return httpHeaders;
            }
        };
    }
}
@Slf4j
@Component
public class HallProviderFallback implements FallbackProvider {
    @Override
    public String getRoute() {
        return "hall.service";
    }

    @Override
    public ClientHttpResponse fallbackResponse(String route, Throwable cause) {
        return new ClientHttpResponse() {
            //ClientHttpResponse的fallback状态码，返回HttpStatus
            @NonNull
            @Override
            public HttpStatus getStatusCode() {
                return HttpStatus.INTERNAL_SERVER_ERROR;
            }

            //ClientHttpResponse的fallback状态码，返回int
            @Override
            public int getRawStatusCode() {
                return this.getStatusCode().value();
            }

            //ClientHttpResponse的fallback状态码，返回String
            @NonNull
            @Override
            public String getStatusText() {
                return this.getStatusCode().getReasonPhrase();
            }

            //回收资源方法，用于回收当前fallback逻辑开启的资源对象
            @Override
            public void close() {

            }

            //设置方法体，Zuul会将本方法返回的输入流数据读取，并且通过HttpServletResponse的输出流输出到客户端
            @NonNull
            @Override
            public InputStream getBody() {
                String result = "影厅服务不可用";
                return new ByteArrayInputStream(result.getBytes(StandardCharsets.UTF_8));
            }

            //设置响应头
            @NonNull
            @Override
            public HttpHeaders getHeaders() {
                HttpHeaders httpHeaders = new HttpHeaders();
                httpHeaders.setContentType(new MediaType("application", "json", StandardCharsets.UTF_8));
                return httpHeaders;
            }
        };
    }
}

(3).film服务修改

@Slf4j
@RestController
@RequestMapping("/films")
public class FilmController {
    @Autowired
    private IFilmService filmService;

    @Value("${server.port}")
    private int port;

    public ServerResponse findFilmListFallback(@RequestBody BasePageVO basePageVO) throws CommonServiceException {
        log.error("film time:{}", System.currentTimeMillis());
        return ServerResponse.createByErrorCodeMessage(500, "请求处理降级返回");
    }

    //获取电影列表
    @HystrixCommand(fallbackMethod = "findFilmListFallback", commandProperties = {
            @HystrixProperty(name = "execution.isolation.strategy", value = "THREAD"),
            @HystrixProperty(name = "execution.isolation.thread.timeoutInMilliseconds", value = "900"),
            @HystrixProperty(name = "circuitBreaker.requestVolumeThreshold", value = "10"),
            @HystrixProperty(name = "circuitBreaker.errorThresholdPercentage", value = "50")
    }, threadPoolProperties = {
            @HystrixProperty(name = "coreSize", value = "10"),
            @HystrixProperty(name = "keepAliveTimeMinutes", value = "1000"),
            @HystrixProperty(name = "maxQueueSize", value = "10"),
            @HystrixProperty(name = "queueSizeRejectionThreshold", value = "8"),
            @HystrixProperty(name = "metrics.rollingStats.numBuckets", value = "12"),
            @HystrixProperty(name = "metrics.rollingStats.timeInMilliseconds", value = "1500")
    }, ignoreExceptions = {CommonServiceException.class})
    @RequestMapping(value = "/findFilmList", method = RequestMethod.POST)
    public ServerResponse findFilmList(@RequestBody BasePageVO basePageVO) throws CommonServiceException, InterruptedException {
        //检查入参
        basePageVO.checkParam();
        if (basePageVO.getPageSize() > 1000) {
            //休眠1秒，触发超时熔断
            Thread.sleep(1000);
        }

        //调用逻辑层，获取返回参数
        IPage<Film> results = filmService.findFilmList(basePageVO.getCurrentPage(), basePageVO.getPageSize());

        return ServerResponse.createBySuccess(PageUtil.getPageResult(results));
    }
}

(4).测试

启动项目，然后在postman中请求“localhost:8080/movies/film-api/films/findFilmList”，可以查询到相应的信息，测试结果如下图所示。

9.Hystrix实践篇_状态码_06


在postman中请求“localhost:8080/movies/hall-api/halls/findFilmListByHallIds”，可以查询到相应的信息，测试结果如下图所示。

9.Hystrix实践篇_java_07

(5).zuul服务工程目录结构

9.Hystrix实践篇_hystrix_08


阿里云国内75折 回扣 微信号：monov8
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