Spring MVC Interceptor 实现性能监控的功能代码

利用Spring MVC 的 Interceptor 实现个简易的性能监控，计算一下每个url的执行时间。

在 preHandle 方法中记录当前的时间戳到线程局部变量里，然后在afterCompletion方法中，用当前的时间戳剪掉线程局部变量里的时间戳得出个运行时间，并记录到log里。

这只是个简易的性能监控，如果想长期正式的监控性能，请选择其它成熟的产品。

Interceptor

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.core.NamedThreadLocal;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;

public class PerformanceInterceptor implements HandlerInterceptor {

  private final static Logger LOGGER = LoggerFactory.getLogger(PerformanceInterceptor.class);

  private NamedThreadLocal<Long> startTimeThreadLocal = new NamedThreadLocal<Long>("performance");

  @Override
  public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler)
      throws Exception {
    startTimeThreadLocal.set(System.currentTimeMillis());
    return true;
  }

  @Override
  public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler,
      ModelAndView modelAndView) throws Exception {
    return;
  }

  @Override
  public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex)
      throws Exception {
    long currentTime = System.currentTimeMillis();
    long executeTime = currentTime - startTimeThreadLocal.get();
    LOGGER.info("uri：{} 执行了 {} 毫秒", request.getRequestURI(), executeTime);
  }

}

这里的是NamedThreadLocal没啥神器的，源码如下：

package org.springframework.core;

import org.springframework.util.Assert;

public class NamedThreadLocal<T> extends ThreadLocal<T> {

  private final String name;

  public NamedThreadLocal(String name) {
    Assert.hasText(name, "Name must not be empty");
    this.name = name;
  }

  @Override
  public String toString() {
    return this.name;
  }

}

定义完Interceptor，注册即可。

import java.util.List;

import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
import org.springframework.boot.web.filter.OrderedCharacterEncodingFilter;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.http.converter.HttpMessageConverter;
import org.springframework.web.filter.CharacterEncodingFilter;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.ResourceHandlerRegistry;
import org.springframework.web.servlet.config.annotation.ViewControllerRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;

import com.vnierlai.scm.webapp.interceptor.PerformanceInterceptor;

@Configuration
public class WebMvcConfigurer extends WebMvcConfigurerAdapter {

  @Bean
  @ConditionalOnMissingBean(CharacterEncodingFilter.class)
  public CharacterEncodingFilter characterEncodingFilter() {
    CharacterEncodingFilter filter = new OrderedCharacterEncodingFilter();
    filter.setEncoding("UTF-8");
    return filter;
  }

  @Override
  public void addInterceptors(InterceptorRegistry registry) {
    registry.addInterceptor(new PerformanceInterceptor()).addPathPatterns("/**");
    super.addInterceptors(registry);
  }

  @Override
  public void addResourceHandlers(ResourceHandlerRegistry registry) {
    registry.addResourceHandler("/webjars/**").addResourceLocations("classpath:/META-INF/resources/webjars/");
    // registry.addResourceHandler("/resources/**").addResourceLocations("/resources/");
  }

}

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