java HttpServlet 之 HttpServletRequest请求

1.获取方法 post 或者 get 或者其他

String method = req.getMethod();
resp.getWriter().write("<h3>1.请求方法:</h3>"+method);

2.获取请求参数

        Enumeration<String> parameterNames = req.getParameterNames();
        resp.getWriter().write("<h5>2.请求参数:</h5>");
        if(!parameterNames.hasMoreElements())
        {
            resp.getWriter().write("无 <br />");
        }
        while (parameterNames.hasMoreElements())
        {
            String name = parameterNames.nextElement();
            String[] vals = req.getParameterValues(name);
            resp.getWriter().write(name+":");
            for (String val: vals) {
                resp.getWriter().write(val+" ");
            }
            resp.getWriter().write("<br />");

        }
        resp.getWriter().write("或者 <br />");
        Map<String,String[]> stringMap=req.getParameterMap();
        for (Map.Entry<String,String[]> entry:stringMap.entrySet())
        {
            resp.getWriter().write(entry.getKey()+":");
            for(String str:entry.getValue())
            {
                resp.getWriter().write(str+" ");
            }
            resp.getWriter().write("<br />");
        }

3.获取请求头

 
        Enumeration<String> headerNames = req.getHeaderNames();
        resp.getWriter().write("<h5>3.请求头:</h5>");
        if(!headerNames.hasMoreElements())
        {
            resp.getWriter().write("无 <br />");
        }

        while(headerNames.hasMoreElements())
        {
            String name=headerNames.nextElement();
            String val=req.getHeader(name);
            resp.getWriter().write(name+":"+val+"<br />");
        }

4.获取请求资源

        resp.getWriter().write("<h5>4.请求资源:</h5>");
        String requestURI = req.getRequestURI();
        resp.getWriter().write("requestURI"+":"+requestURI+"<br />");
        StringBuffer requestURL = req.getRequestURL();
        resp.getWriter().write("requestURL"+":"+requestURL+"<br />");
        String contextPath = req.getContextPath();
        resp.getWriter().write("contextPath(web应用名称)"+":"+contextPath+"<br />");
        String queryString = req.getQueryString();
        resp.getWriter().write("queryString(GET后的参数列表)"+":"+queryString+"<br />");

5.获取客户机的参数

 
        resp.getWriter().write("<h5>5.客户端参数:</h5>");
        String remoteUser = req.getRemoteUser();
        resp.getWriter().write("remoteUser"+":"+remoteUser+"<br />");
        String remoteHost = req.getRemoteHost();
        resp.getWriter().write("remoteHost"+":"+remoteHost+"<br />");
        String remoteAddr = req.getRemoteAddr();
        resp.getWriter().write("remoteAddr"+":"+remoteAddr+"<br />");
        int remotePort = req.getRemotePort();
        resp.getWriter().write("remotePort"+":"+remotePort+"<br />");

6.获取request域对象

        //设置域对象 （一次请求）
        req.setAttribute("姓名",new String("神奇的我"));
        req.setAttribute("数字",new Integer(23));
        req.setAttribute("时间",new Date());
        //输出域对象
        resp.getWriter().write("<h5>6.request域对象(存储数据的区域对象):</h5>");
        Enumeration<String> attributeNames = req.getAttributeNames();
        while (attributeNames.hasMoreElements())
        {
            String name=attributeNames.nextElement();
            Object val = req.getAttribute(name);
            resp.getWriter().write(name+":"+val.toString()+"<br />");
        }
        //移除域对象
        /* 先不移除 看看 在转发之后 还能不能获取到
        Enumeration<String> attributeNames2 = req.getAttributeNames();
        while (attributeNames2.hasMoreElements())
        {
            String name=attributeNames2.nextElement();
            req.removeAttribute(name);
        }
        */

7.request请求转发

        //获取转发
        RequestDispatcher requestDispatcher = req.getRequestDispatcher("/demo2");
        //执行
        //include方法 包含在原来地方
        //requestDispatcher.include(req,resp);
        //forward方法 重新开
        requestDispatcher.forward(req,resp);

测试工程war包:百度云:https://pan.baidu.com/s/1pL9PQ6B  密码:atkv