偶发：访问静态资源不定时报400问题

背景：

        接手公司一个web系统，在浏览器访问静态资源的时候，一次成功，一次失败，出现几率1:1,查询资料得知，请求头中的If-None-Match对应的值中含有 " 号，在传到服务端时会被转义为

"  ，导致服务端在根据此参数判断是否返回缓存信息时，比对失败报错，此处加以过滤器进行过滤即可。

处理代码如下：

import org.apache.commons.lang3.StringUtils;

import javax.servlet.Filter;
import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;
import java.io.IOException;
import java.util.*;

/**
 * 解决访问静态资源报400问题
 */
public class StaticFilter implements Filter {

    @Override
    public void init(FilterConfig filterConfig) {}

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        HttpServletRequest httpRequest = (HttpServletRequest) servletRequest;
        HeaderMapRequestWrapper requestWrapper = new HeaderMapRequestWrapper(httpRequest);
        String header = httpRequest.getHeader("If-None-Match");
        if(StringUtils.isNotEmpty(header)){
            header = header.replace(""","\"").replace("%2f", "/");;
            requestWrapper.addHeader("If-None-Match", header);
        }
        filterChain.doFilter(requestWrapper, servletResponse);
    }

    @Override
    public void destroy() { }
}
class HeaderMapRequestWrapper extends HttpServletRequestWrapper {
    public HeaderMapRequestWrapper(HttpServletRequest request) {
        super(request);
    }

    private Map<String, String> headerMap = new HashMap<>();

    public void addHeader(String name, String value) {
        headerMap.put(name, value);
    }
    @Override
    public String getHeader(String name) {
        String headerValue = super.getHeader(name);
        if (headerMap.containsKey(name)) {
            headerValue = headerMap.get(name);
        }
        return headerValue;
    }

    /**
     * get the Header names
     */
    @Override
    public Enumeration<String> getHeaderNames() {
        List<String> names = Collections.list(super.getHeaderNames());
        for (String name : headerMap.keySet()) {
            names.add(name);
        }
        return Collections.enumeration(names);
    }

    @Override
    public Enumeration<String> getHeaders(String name) {
        List<String> values = Collections.list(super.getHeaders(name));
        if (headerMap.containsKey(name)) {
            values = Arrays.asList(headerMap.get(name));
        }
        return Collections.enumeration(values);
    }
}

web.xml配置如下：

 <filter>
    <filter-name>staticFilter</filter-name>
    <filter-class>javacommon.filter.StaticFilter</filter-class>
 </filter>
 <filter-mapping>
     <filter-name>staticFilter</filter-name>
     <url-pattern>/public/*</url-pattern>
  </filter-mapping>
  <filter-mapping>
      <filter-name>staticFilter</filter-name>
      <url-pattern>/scripts/*</url-pattern>
  </filter-mapping>