想要创建一个过滤器来检查cookie,然后从控制器保存对象和引用

Question

我想创建一个在我的任何spring mvc控制器操作之前执行的过滤器.

我想检查cookie的存在,然后只为当前请求存储一个对象.

然后我需要从我的控制器动作中引用这个对象(如果它存在).

关于如何做到这一点的建议？

Answer 1

创建过滤器只是创建一个实现javax.servlet.Filter的类,在你的情况下可以是这样的

public class CookieFilter implements Filter {
    public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException, ServletException {
        HttpServletRequest request = (HttpServletRequest) req;
        
        Cookie[] cookies = request.getCookies();
        if (cookies != null){
          for (Cookie ck : cookies) {
            if ("nameOfMyCookie".equals(ck.getName())) {
                // read the cookie etc, etc
                // ....
                // set an object in the current request
                request.setAttribute("myCoolObject", myObject)
            }
        }
        chain.doFilter(request, res);
    }
    public void init(FilterConfig config) throws ServletException {
        // some initialization code called when the filter is loaded
    }
    public void destroy() {
        // executed when the filter is unloaded
    }
}

然后在web.xml中声明过滤器

<filter>
    <filter-name>CookieFilter</filter-name>
    <filter-class>
        my.package.CookieFilter
    </filter-class>
</filter>
<filter-mapping>
    <filter-name>CookieFilter</filter-name>
    <url-pattern>/*</url-pattern>
</filter-mapping>

此时在您的控制器中,只需使用request.getAttribute("myCoolObject")检查请求中是否存在attibute