5.1 Request 获取请求数据的几种方法

 //获取请求头和请求数据
 //请求数据（1.通过超链接 2.通过表单）
 //获取请求数据的时候一般来说  都要先检查  再使用
 public class RequestDemo2 extends HttpServlet {

     //获取数据的相关方法
     public void doGet(HttpServletRequest request, HttpServletResponse response)
             throws ServletException, IOException {

         System.out.println("-----------获取数据方式1-------------");

         String value = request.getParameter("username");
         if(value != null && !value.trim().equals("")) {
             System.out.println(value);
         }

         System.out.println("-----------获取数据方式2----------- -");

         Enumeration e = request.getParameterNames();
         while(e.hasMoreElements()) {
             String name = (String) e.nextElement();
             value = request.getParameter(name);
             System.out.println(name + "=" + value);
         }

         System.out.println("-----------获取数据方式3-------------");

         String[] values = request.getParameterValues("username");

         for(int i = 0;i<values.length && values[i] != null;i++) {
             System.out.println(values[i]);
         }

         System.out.println("-----------获取数据方式4-------------");
         /*使用Map  （常用）*/
         /*Map<String,String[]> map = request.getParameterMap();
         User user = new User();
         try {
             BeanUtils.populate(user, map);   //用map集合的数据填充bean
             BeanUtils.copyProperties(user, formbean);
         } catch(Exception e1) {
             e1.printStackTrace();
         }*/

         System.out.println("-----------获取数据方式5-------------");     //用于文件上传

         InputStream in = request.getInputStream();

         int len = 0;
         byte[] buffer = new byte[1024];
         while((len = in.read()) > 0) {
             System.out.print(new String(buffer,0,len));
         }
     }    

     //获取头的相关方法
     private void test1(HttpServletRequest request) {
         String HeadValue = request.getHeader("Accept-Encoding");
         System.out.println(HeadValue);

         System.out.println("-------------------------");    

         Enumeration e = request.getHeaders("Accept-Encoding");
         while(e.hasMoreElements()) {
             String value = (String) e.nextElement();
             System.out.println(value);
         }

         System.out.println("-------------------------");    

         e = request.getHeaderNames();

         while(e.hasMoreElements()) {
             String name = (String) e.nextElement();
             String value = request.getHeader(name);
             System.out.println(name + "=" + value);
         }
     }

     public void doPost(HttpServletRequest request, HttpServletResponse response)
             throws ServletException, IOException {
         doGet(request, response);
     }

 }

 //获取请求头和请求数据
 //请求数据（1.通过超链接 2.通过表单）
 //获取请求数据的时候一般来说  都要先检查  再使用
 public class RequestDemo2 extends HttpServlet {

     //获取数据的相关方法
     public void doGet(HttpServletRequest request, HttpServletResponse response)
             throws ServletException, IOException {

         System.out.println("-----------获取数据方式1-------------");

         String value = request.getParameter("username");
         if(value != null && !value.trim().equals("")) {
             System.out.println(value);
         }

         System.out.println("-----------获取数据方式2----------- -");

         Enumeration e = request.getParameterNames();
         while(e.hasMoreElements()) {
             String name = (String) e.nextElement();
             value = request.getParameter(name);
             System.out.println(name + "=" + value);
         }

         System.out.println("-----------获取数据方式3-------------");

         String[] values = request.getParameterValues("username");

         for(int i = 0;i<values.length && values[i] != null;i++) {
             System.out.println(values[i]);
         }

         System.out.println("-----------获取数据方式4-------------");
         /*使用Map  （常用）*/
         /*Map<String,String[]> map = request.getParameterMap();
         User user = new User();
         try {
             BeanUtils.populate(user, map);   //用map集合的数据填充bean
             BeanUtils.copyProperties(user, formbean);
         } catch(Exception e1) {
             e1.printStackTrace();
         }*/

         System.out.println("-----------获取数据方式5-------------");     //用于文件上传

         InputStream in = request.getInputStream();

         int len = 0;
         byte[] buffer = new byte[1024];
         while((len = in.read()) > 0) {
             System.out.print(new String(buffer,0,len));
         }
     }    

     //获取头的相关方法
     private void test1(HttpServletRequest request) {
         String HeadValue = request.getHeader("Accept-Encoding");
         System.out.println(HeadValue);

         System.out.println("-------------------------");    

         Enumeration e = request.getHeaders("Accept-Encoding");
         while(e.hasMoreElements()) {
             String value = (String) e.nextElement();
             System.out.println(value);
         }

         System.out.println("-------------------------");    

         e = request.getHeaderNames();

         while(e.hasMoreElements()) {
             String name = (String) e.nextElement();
             String value = request.getHeader(name);
             System.out.println(name + "=" + value);
         }
     }

     public void doPost(HttpServletRequest request, HttpServletResponse response)
             throws ServletException, IOException {
         doGet(request, response);
     }

 }