场景：过滤器中获取参数Token并添加到请求头(用户认证兼容老系统)

请求头和请求参数是不能直接修改，也没有提供修改的方法，但是可以在过滤器和拦截器中使用HttpServletRequestWrapper包装类达到修改的目的。

一、实现HttpServletRequestWrapper接口，下面直接使用匿名类

package com.xxxx.web.filter;

import org.apache.commons.lang3.StringUtils;

import javax.servlet.*;

import javax.servlet.annotation.WebFilter;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletRequestWrapper;

import java.io.IOException;

import java.util.Enumeration;

@WebFilter

public class AuthHeaderSettingFilter implements Filter{

@Override

public void init(FilterConfig filterConfig) throws ServletException {

}

@Override

public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {

HttpServletRequestWrapper requestWrapper = new HttpServletRequestWrapper((HttpServletRequest) request) {

/**

* 当调用request.getHeader("token")时，则获取请求参数中token值并当做Header的值返回

* @param name

* @return

*/

@Override

public String getHeader(String name) {

// 先从原本的Request中获取头，如果为空且名字为token，则从参数中查找并返回

String superHeader = super.getHeader(name);

if("token".equals(name) && StringUtils.isEmpty(superHeader)){

String token = request.getParameter("token");

if (StringUtils.isNotEmpty(token)) {

return token ;

}

}

return superHeader;

}

};

chain.doFilter(requestWrapper,response);

}

@Override

public void destroy() {

}

}

二、HttpServletRequestWrapper、ServletRequestWrapper和HttpServletRequest接口中的很多方法都可以重写

要想增加一个请求参数可以在HttpServletRequestWrapper中重写getParameter(String name)

@Override

public String getParameter(String name) {

if("newParam".equals(name)){

return "这是我新增加的参数";

}

return super.getParameter(name);

}

@Override

public Map getParameterMap() {

HashMap newMap = new HashMap<>();

newMap.putAll(super.getParameterMap());

newMap.put("newParam",new String[]{"这是我新增加的参数"}) ;

return Collections.unmodifiableMap(newMap);

}

@Override

public String[] getParameterValues(String name) {

if("newParam".equals(name)){

return new String[]{"这是我新增加的参数"};

}

return super.getParameterValues(name);

}

注意： getParameterMap()返回的时一个不可修改的map ,不能直接向里面put值， 所以在重写这个方法时要自己new 一个HashMap ，然后在新建的map中放值，最后返回时必须调用Collections.unmodifiableMap(Map extends K, ? extends V> m) 把map改成不可变的

结构

image.png

image.png

参考：

作者：else05

链接：https://www.jianshu.com/p/a8c9d45775ea

来源：简书

简书著作权归作者所有，任何形式的转载都请联系作者获得授权并注明出处。

背景

由于环境升级，需要重新设置header中的 一个值，暂设定为 org . http 请求时加入在header中加入org,但在filter中，会通过验证，生成新的org，需要覆盖原来header中的org.

修改 filter 。代码是在网上找的一部分，根据自己的需要进行调整了。

@Component

@Slf4j

@WebFilter(urlPatterns = { "/" }, filterName = "authorFilter")

public class DemoFilter implements Filter {

@Override public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse,

FilterChain filterChain) throws IOException, ServletException {

HttpServletRequest req = (HttpServletRequest) servletRequest;

req.setAttribute("hdd","tttt");

HeaderMapRequestWrapper requestWrapper = new HeaderMapRequestWrapper(req);

requestWrapper.addHeader("realm","test");

log.info("header-->{}",getHeadKeyAndValue(req));

filterChain.doFilter(requestWrapper, servletResponse);

}

private Map getHeadKeyAndValue(HttpServletRequest httpRequest) {

Map header = new HashMap<>();

Enumeration headerNames = httpRequest.getHeaderNames();

while (headerNames.hasMoreElements()) {

String nextElement = headerNames.nextElement();

header.put(nextElement, httpRequest.getHeader(nextElement));

}

return header;

}

}

@Slf4j

public class HeaderMapRequestWrapper extends HttpServletRequestWrapper {

/**

* construct a wrapper for this request

*

* @param request

*/

public HeaderMapRequestWrapper(HttpServletRequest request) {

super(request);

}

private Map headerMap = new HashMap<>();

/**

* 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) {

log.info("getHeader --->{}",name);

String headerValue = super.getHeader(name);

if (headerMap.containsKey(name)) {

headerValue = headerMap.get(name);

}

return headerValue;

}

/**

* get the Header names

*/

@Override

public Enumeration getHeaderNames() {

List names = Collections.list(super.getHeaderNames());

for (String name : headerMap.keySet()) {

names.add(name);

}

return Collections.enumeration(names);

}

@Override

public Enumeration getHeaders(String name) {

log.info("getHeaders --->>>>>>{}",name);

List values = Collections.list(super.getHeaders(name));

log.info("getHeaders --->>>>>>{}",values);

if (headerMap.containsKey(name)) {

log.info("getHeaders --->{}",headerMap.get(name));

values = Arrays.asList(headerMap.get(name));

}

return Collections.enumeration(values);

}

}

经过测试，在header解析时，是通过getHeaders方法，这个地方原来的时候是通过，values直接添加新的header,组成了一个 header的数组，而不是覆盖。

实现功能：

所有接口经过过滤器，获取每个接口的自定义头部(token)

判断如果是app访问，则给头部设置cookie，值为自定义token的值。

即：使用过滤器实现修改请求头headers

实现步骤：

1.自定义过滤器 ModifyParametersFilter.java 并继承 OncePerRequestFilter

package com.mobile.web.common;

import org.springframework.web.filter.OncePerRequestFilter;

import javax.servlet.FilterChain;

import javax.servlet.ServletException;

import javax.servlet.http.Cookie;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletRequestWrapper;

import javax.servlet.http.HttpServletResponse;

import java.io.IOException;

import java.util.*;

/**

* 自定义的过滤器,

* Created by Administrator on 2017/6/19 0019.

*/

public class ModifyParametersFilter extends OncePerRequestFilter {

@Override

protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain)

throws ServletException, IOException {

// 修改cookie

ModifyHttpServletRequestWrapper mParametersWrapper = new ModifyHttpServletRequestWrapper(request);

String token = request.getHeader("token");

if (token != null && !"".equals(token)) {

mParametersWrapper.putCookie("JSESSIONID", token);

}

// finish

filterChain.doFilter(mParametersWrapper, response);

}

/**

* 修改cookie信息

*/

private class ModifyHttpServletRequestWrapper extends HttpServletRequestWrapper {

private Map mapCookies;

ModifyHttpServletRequestWrapper(HttpServletRequest request) {

super(request);

this.mapCookies = new HashMap<>();

}

void putCookie(String name, String value) {

this.mapCookies.put(name, value);

}

public Cookie[] getCookies() {

HttpServletRequest request = (HttpServletRequest) getRequest();

Cookie[] cookies = request.getCookies();

if (mapCookies == null || mapCookies.isEmpty()) {

return cookies;

}

if (cookies == null || cookies.length == 0) {

List cookieList = new LinkedList<>();

for (Map.Entry entry : mapCookies.entrySet()) {

String key = entry.getKey();

if (key != null && !"".equals(key)) {

cookieList.add(new Cookie(key, entry.getValue()));

}

}

if (cookieList.isEmpty()) {

return cookies;

}

return cookieList.toArray(new Cookie[cookieList.size()]);

} else {

List cookieList = new ArrayList<>(Arrays.asList(cookies));

for (Map.Entry entry : mapCookies.entrySet()) {

String key = entry.getKey();

if (key != null && !"".equals(key)) {

for (int i = 0; i < cookieList.size(); i++) {

if(cookieList.get(i).getName().equals(key)){

cookieList.remove(i);

}

}

cookieList.add(new Cookie(key, entry.getValue()));

}

}

return cookieList.toArray(new Cookie[cookieList.size()]);

}

}

}

}

2.在web.xml中注册该过滤器：

ModifyParametersFilter

com.xiyinli.web.common.ModifyParametersFilter

ModifyParametersFilter

/*

REQUEST

FORWARD

如：

参考文章：