在springBoot中便捷解析controller参数

最近在用SpringBoot2.0和redis搞分布式session,涉及到从response中取出session的token值,这个方法每次都要在controller中传入HttpServletResponse对象,以及硬传入token的值,显得比较繁琐,于是想能不能通过Spring直接解析出request中附带的token值,然后直接在controller中传入pojo对象,即将解析的代码提取出来,于是找到了相应的方法.
首先新建一个类实现WebMvcConfigurationSupport,在SpringBoot2.0或Spring5以下的版本也可以实现WebMvcConfigurerAdapter(新版本已废弃)

  @Configuration
public class WebConfig extends WebMvcConfigurationSupport {
    @Autowired
    private UserArgumentResolver resolver;

    @Override
    protected void addArgumentResolvers(List<HandlerMethodArgumentResolver> argumentResolvers) {
        argumentResolvers.add(resolver);
        super.addArgumentResolvers(argumentResolvers);

    }
}  

由于我们要写一个自定义的参数解析器,自然就重写他的addArgumentResolvers方法,看这个方法的参数是一个List集合里面的元素是HandlerMethodArgumentResolver,自然我们就要自己写一个,这是个接口.

package cn.paul.spike.config;

import cn.paul.spike.domain.User;
import cn.paul.spike.service.UserService;
import com.alibaba.druid.util.StringUtils;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.core.MethodParameter;
import org.springframework.stereotype.Component;
import org.springframework.web.bind.support.WebDataBinderFactory;
import org.springframework.web.context.request.NativeWebRequest;
import org.springframework.web.method.support.HandlerMethodArgumentResolver;
import org.springframework.web.method.support.ModelAndViewContainer;

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

import static cn.paul.spike.service.UserService.COOKIE_NAME_TOKEN;

/**
 * @author Paul
 * @version 0.1
 * @date 2018/3/15 0015
 */
@Component
public class UserArgumentResolver implements HandlerMethodArgumentResolver {
    @Autowired
    private UserService userService;

    @Override
    public boolean supportsParameter(MethodParameter parameter) {
        Class<?> aClass = parameter.getParameterType();
        return aClass == User.class;
    }

    @Override
    public Object resolveArgument(MethodParameter parameter, ModelAndViewContainer mavContainer, NativeWebRequest webRequest, WebDataBinderFactory binderFactory) throws Exception {
        HttpServletRequest request = webRequest.getNativeRequest(HttpServletRequest.class);
        HttpServletResponse response = webRequest.getNativeResponse(HttpServletResponse.class);
        String paramToken = request.getParameter(COOKIE_NAME_TOKEN);
        String cookieToken = getCookieValue(request, COOKIE_NAME_TOKEN);
        if (StringUtils.isEmpty(cookieToken) && StringUtils.isEmpty(paramToken)) {
            return null;
        }
        String token = StringUtils.isEmpty(paramToken) ? cookieToken : paramToken;
        User user = userService.getByToken(response, token);
        return user;
    }

    private String getCookieValue(HttpServletRequest request, String cookieNameToken) {
        Cookie[] cookies = request.getCookies();
        for (Cookie cookie : cookies) {
            if (cookie.getName().equals(cookieNameToken)) {
                return cookie.getValue();
            }
        }
        return null;
    }
}