-
@author linzhiqiang
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@date 2019/4/17
*/
public abstract class AbstractInterceptor extends HandlerInterceptorAdapter {
private Logger logger = LoggerFactory.getLogger(AbstractInterceptor.class);
@Override
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
ResponseEnum result;
try {
result = preFilter(request);
} 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.RATE_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：
