全局Request(Thread+Filter)

1.fiter

新建一個普通的java類，讓它實現Filter，重寫Filter的方法。然後在web.xml中，配置這個自定義的過濾器，使其生效。

package com.fh.common;
import com.fh.util.WebRequestUtil;
import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import java.io.IOException;
public class WebContextFilter implements Filter {
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
    }
    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
        HttpServletRequest req = (HttpServletRequest) request;
        WebRequestUtil.setRequest(req);
        try {
            //執行所有過濾器鏈表
            chain.doFilter(request,response);
        } catch (IOException e) {
            e.printStackTrace();
        } catch (ServletException e) {
            e.printStackTrace();
        }finally{
            //在方法完成後移除當前線程
            WebRequestUtil.remove();
        }
    }
    @Override
    public void destroy() {
    }
}

2.WebRequestUtil

package com.fh.util;
import javax.servlet.http.HttpServletRequest;
public class WebRequestUtil {
    private static ThreadLocal<HttpServletRequest> threadLocal = new ThreadLocal();
    public static void setRequest(HttpServletRequest request){
    //當前線程作爲key
        threadLocal.set(request);
    }
    public static HttpServletRequest getRequest(){
        return threadLocal.get();
    }
    public static void remove(){
        threadLocal.remove();
    }
}

3.web.xml配置filter

<!--配置全局request-->
  <filter>
    <filter-name>WebContextFilter</filter-name>
    <filter-class>com.fh.common.WebContextFilter</filter-class>
  </filter>
  <filter-mapping>
    <filter-name>WebContextFilter</filter-name>
    <url-pattern>*.do</url-pattern>
  </filter-mapping>