使用Guava实现限流器，mybatis获取自增主键的原理

使用Guava实现限流器，mybatis获取自增主键的原理

} catch (Exception e) {

logger.error(“preHandle catch a exception:” + e.getMessage());

result = ResponseEnum.FAIL;

}

if (ResponseEnum.SUCCESS.code.equals(result.code)) {

return true;

}

handlerResponse(result, response);

return false;

}

protected abstract ResponseEnum preFilter(HttpServletRequest request);

private void handlerResponse(ResponseEnum result, HttpServletResponse response) {

ResponseDto responseDto = new ResponseDto();

responseDto.setCode(result.code);

responseDto.setStatus(result.status);

responseDto.setMessage(result.message);

response.setStatus(HttpServletResponse.SC_OK);

response.setContentType(MediaType.APPLICATION_JSON_UTF8_VALUE);

PrintWriter printWriter = null;

try {

printWriter = response.getWriter();

printWriter.write(JsonUtils.toJson(responseDto));

} catch (Exception e) {

logger.error(“handlerResponse catch a exception:” + e.getMessage());

} finally {

if (printWriter != null) {

printWriter.close();

}

}

}

}

b）定义流量控制拦截器，流量控制拦截器继承自上面的拦截器抽象类，在preFilter方法中进行流量控制。

@Component(“rateLimitInterceptor”)

public class RateLimitInterceptor extends AbstractInterceptor {

private Logger logger = LoggerFactory.getLogger(RateLimitInterceptor.class);

private static final RateLimiter rateLimiter = RateLimiter.create(300);

public static void setRate(double limiterQPS){

rateLimiter.setRate(limiterQPS);

}

@Override

protected ResponseEnum preFilter(HttpServletRequest request) {

if (!rateLimiter.tryAcquire()) {

logger.warn(“限流中…”);

return ResponseEnum.RATE_LIMIT;

}

return ResponseEnum.SUCCESS;

}

}

使用Guava提供的RateLimiter类来实现流量控制，过程很简单：定义了一个QPS为1的全局限流器（便于测试），使用tryAcquire()方法来尝试获取令牌，如果成功则返回ResponseEnum.OK，否则返回ResponseEnum.R

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ATE_LIMIT。

3.继承WebMvcConfigurerAdapter来添加自定义拦截器

@Configuration

public class MyWebAppConfigurer extends WebMvcConfigurationSupport {

@Override

public void addInterceptors(InterceptorRegistry registry) {

// 多个拦截器组成一个拦截器链

// addPathPatterns 用于添加拦截规则

// excludePathPatterns 用户排除拦截

registry.addInterceptor(new RateLimitInterceptor()).addPathPatterns("

@RequestMapping(value = “getUserList”, method = RequestMethod.GET)

public String getUserList() {

String result = null;

try {

result = “请求成功”;

}catch (Exception e){

logger.error(“请求失败”, e);

return JsonUtils.toJson(ResponseUtils.failInServer(result));

}

return JsonUtils.toJson(ResponseUtils.success(result));

}

上文使用到的ResponseEnum是一个返回Code的枚举：

public enum ResponseEnum {

SUCCESS(“200”,“000000”,“请求成功”),

FAIL(“200”,“100000”,“请求失败”),

FAIL_BY_PARAMS(“200”,“200000”,“请求参数异常”),

FAIL_IN_SERVER(“200”,“300000”,“服务器内部异常”),

RATE_LIMIT(“200”,“400000”,“限流中”);

public String status;

public String code;

public String message;

ResponseEnum(String s, String s1, String s2) {

this.status = s;

this.code = s1;

this.message = s2;

}

}

5.使用Postman来测试接口

快速并且反复的调用接口，可以很容易的看到两种结果。

成功通过限流器的结果：