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

问题描述

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。

我想检查是否存在cookie，然后存储只有当前请求的某个对象。

然后我需要在我的控制器操作中引用此对象（如果存在）。 / p>

有关如何执行此操作的建议？

解决方案

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

  public class CookieFilter实现Filter { 
 public void doFilter（ServletRequest req，ServletResponse res，FilterChain chain）抛出IOException，ServletException {
 HttpServletRequest request =（HttpServletRequest）req; 
 
 Cookie [] cookies = request.getCookies（）; 
 if（cookies！= null）{
 for（Cookie ck：cookies）{
 if（nameOfMyCookie.equals（ck.getName（）））{
 //读取cookie等等
 // .... .... 
 //在当前请求中设置一个对象
 request.setAttribute（myCoolObject，myObject）
} 
} 
 chain.doFilter（request，res）; 
} 
 public void init（FilterConfig config）抛出ServletException {
 //加载过滤器时调用的一些初始化代码
} 
 public void destroy（）{
 //在卸载过滤器时执行
} 
} 
  

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> 
  

此时您的控制器只需使用request.getAttribute检查请求中是否存在attibute（ myCoolObject）

I want to create a filter that will execute before any of my spring mvc controller actions.

I want to check for the existence of a cookie, and then store an object somewhere for the current request only.

I then need to reference this object (if it exists) from within my controller action.

Suggestions on how to do this?

解决方案

to create the filter just make a class that implements javax.servlet.Filter, in your case can be something like this

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
    }
}

then declare the filter in your web.xml

<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>

at this point in your controller just check if the attibute exists in the request using request.getAttribute("myCoolObject")

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