HttpServletRequest + Filter 添加 header

HttpServletRequest + Filter 添加 header

Filter 能够获得 HttpServletRequest 暴露的接口，但由于 HttpServletRequets 没有 setter方法，因此HttpServletRequest 是只可读的。但很多情况需要往HttpServletRequset 添加 header 参数，例如 token、userId。

1、自定义配置类

配置类继承 HttpServletRequestWrapper

public class CustomHttpServletRequest extends HttpServletRequestWrapper {
    private final Map<String, String> hashMap;

    /**
     * 初始化
     *
     * @param request
     */
    public CustomHttpServletRequest(HttpServletRequest request) {
        super(request);
        hashMap = new HashMap<>();
    }

    /**
     * 添加key、value
     *
     * @param key
     * @param value
     */
    public void addHeader(String key, String value) {
        hashMap.put(key, value);
    }

    /**
     * 获得value
     *
     * @param key
     * @return
     */
    @Override
    public String getHeader(String key) {
        String value = super.getHeader(key);
        if (value == null) {
            value = hashMap.get(key);
        }
        return value;
    }

    /**
     * 获得value集合
     *
     * @param key
     * @return
     */
    @Override
    public Enumeration<String> getHeaders(String key) {
        Enumeration<String> enumeration = super.getHeaders(key);
        List<String> valueList = Collections.list(enumeration);
        if (hashMap.containsKey(key)) {
            valueList.add(hashMap.get(key));
        }
        return Collections.enumeration(valueList);
    }
    
    /**
     * 获得key集合
     *
     * @return
     */
    @Override
    public Enumeration<String> getHeaderNames(){
        List<String> keyList = Collections.list(super.getHeaderNames());
        keyList.addAll(hashMap.keySet());
        return Collections.enumeration(keyList);
    }
}

2、Filter

Filter 调用配置类对象并添加 header

@WebFilter(filterName = "AccessFilter", urlPatterns = "/*")
@Order(1)
public class AccessFilter implements Filter {
    Logger logger = LoggerFactory.getLogger(AccessFilter.class);

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

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        HttpServletRequest request = (HttpServletRequest) servletRequest;
        CustomHttpServletRequest customHttpServletRequest = new CustomHttpServletRequest(request);
        //添加header
        customHttpServletRequest.addHeader("test", "123");
        filterChain.doFilter(customHttpServletRequest, servletResponse);
    }

    @Override
    public void destroy() {
    }

启动类添加 ServletComponentScan注解

@MapperScan({"com.lin.mapper"})
@SpringBootApplication
@EnableTransactionManagement
@ServletComponentScan
public class MybatisPlusApplication {

    public static void main(String[] args) {
        SpringApplication.run(MybatisPlusApplication.class, args);
    }
}

3、测试

调用接口进行测试

@GetMapping(value = "/findById")
@ResponseBody
public Result findById(@RequestParam(value = "id", required = true, defaultValue = "2") Long id,
                       HttpServletRequest request) {
    User user = userService.findById(id);
    logger.info("===========" + request.getHeader("test") + "==========");
    return ResultUtil.success(user);
}

打印出结果：

INFO 13880 --- [nio-8080-exec-2] com.lin.controller.UserController        : ===========123==========

总结：自定义配置类继承 HttpServletRequestWrapper，Filter 调用配置类并添加 header, 接口通过 getheader 方法获得已添加的 header。

参考资料：HttpServletRequest添加header