如何在Java的普通类中获取Session以及request对象

前期准备：创建一个项目，并配置好一些需要的文件。

创建好项目后就创建一个类RequestFilter。

创建RequestFilter类是需要继承一接口，必须是javax.servlet包下的Filter接口。

创建好后在RequestFilter中创建线程：
//创建线程
threadLocalRequest、threadLocalResponse
在doFilter()方法中写
//把request、response传入

import java.io.IOException;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class RequestFilter implements Filter {
//创建线程
public static ThreadLocal<HttpServletRequest> threadLocalRequest = new ThreadLocal<HttpServletRequest>();
public static ThreadLocal<HttpServletResponse> threadLocalResponse = new ThreadLocal<HttpServletResponse>();
public void doFilter(ServletRequest arg0, ServletResponse arg1,
FilterChain arg2) throws IOException, ServletException {
threadLocalRequest.set((HttpServletRequest) arg0);
threadLocalResponse.set((HttpServletResponse) arg1);
arg2.doFilter(arg0, arg1);
}
public void destroy() {
}
public void init(FilterConfig arg0) throws ServletException {
}
}

在类RequestFilter中写好代码后在WEB-INF目录下的web.xml文件中注册此类，

<filter> <filter-name>RequestFilter</filter-name> <filter-class>包名.RequestFilter</filter-class> </filter> <filter-mapping> <filter-name>RequestFilter</filter-name> <url-pattern>/*</url-pattern> </filter-mapping> <filter-mapping>   <filter-name>RequestFilter</filter-name>   <url-pattern>*.do</url-pattern> </filter-mapping>

注册好后就可以在Java类中轻松获取自己在Action或页面上保存在Session中值，具体调用
//获取request
HttpServletRequest request = RequestFilter.threadLocal.get();

request.getSession().getAttribute("所保存的名称");

HttpServletRequest request = RequestFilter.threadLocal.get();这句话一定要放在方法里面，不能放在方法外面。