拦截器实现request请求新增header参数 

TODO:网上找了很多都不行，好不容易找到一个可以的，给大家分享一下！

1、新增拦截器类RemoteAddrFilter.java

2、新增类HeaderMapRequestWrapper.java

3:、done

RemoteAddrFilter.java：

import java.io.IOException;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;

/**
 * @ClassName : RemoteAddrFilter
 * @Description : 
 * @Version 1.0
 */
public class RemoteAddrFilter implements Filter {

    @Override
    public void destroy() {

    }

    @Override
    public void doFilter(ServletRequest request, ServletResponse response,
                         FilterChain chain) throws IOException, ServletException {
        HttpServletRequest req = (HttpServletRequest) request;
        HeaderMapRequestWrapper requestWrapper = new HeaderMapRequestWrapper(req);
        //校验请求request Header中是否有对应值
        String language = request.getParameter("language");
        if (language !=null && !"".equals(language)) {
            //如果get请求url中带有这个参数，则request中新增一个header
            requestWrapper.addHeader("language", language);
            // Goes to default servlet.
            chain.doFilter(requestWrapper, response);
        }
        // Goes to default servlet.
        chain.doFilter(request, response);

    }

    @Override
    public void init(FilterConfig filterConfig) throws ServletException {

    }
}

HeaderMapRequestWrapper.java

import java.util.Collections;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.List;
import java.util.Map;


import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;

/**
 * @ClassName : HeaderMapRequestWrapper
 * @Version 1.0
 */
public class HeaderMapRequestWrapper extends HttpServletRequestWrapper {
    /**
     * construct a wrapper for this request
     *
     * @param request
     */
    public HeaderMapRequestWrapper(HttpServletRequest request) {
        super(request);
    }

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

    /**
     * add a header with given name and value
     *
     * @param name
     * @param value
     */
    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.add(headerMap.get(name));
        }
        return Collections.enumeration(values);
    }

}