Servlet-ServletRequest

Servlet-Service参数

 

  @Override
    public void service(ServletRequest servletRequest, ServletResponse servletResponse) throws ServletException, IOException {

    }

 

  

 

ServletRequest:封装了请求信息,可以从中获取到任何的请求信息

ServletResponse:封装了响应信息,如果想给用户什么响应,具体可以使用该接口的方法实现。

 

这两个接口的实现类是服务器给予实现的,并在服务器调用service方法时传入。

 

1、Servlet-ServletRequest

1)获取请求参数:

  > String getParameter(String name):根据请求参数的名字,返回参数值

  若请求参数有多个值(例如:checkbox),该方法只能获取到第一个提交的值

  >String getParameterValues(String name):根据请求参数的名字,返回请求参数对应的字符串数组

  >Enumeration getParameterNames():返回参数名对应的Enumeration对象,类似于ServletConfig(或ServletContext)的getInitParameterNames()方法

  >Map getParameterMap():返回请求参数的键值对: key:参数名,value:参数值,String数组类型

 

   @Override
    public void service(ServletRequest servletRequest, ServletResponse servletResponse) throws ServletException, IOException {
        System.out.println("请求来了。。。");
        String user = servletRequest.getParameter("username");
        System.out.println(user);
        String interesting = servletRequest.getParameter("interesting");
        System.out.println("__"+interesting);
        String[] param = servletRequest.getParameterValues("interesting");
        /*  atguigu
            __111*/
        for (String interes:param
             ) {
            System.out.println("<>"+interes);
        }
        /*  <>111
            <>222*/
        Enumeration<String> names = servletRequest.getParameterNames();
        while (names.hasMoreElements()){
            String name = names.nextElement();
            String value = servletRequest.getParameter(name);
            System.out.println("- _ -"+name +" "+value);
        }
        /*  - _ -username atguigu
            - _ -password 123
            - _ -interesting 111*/
        Map<String,String[]> map = servletRequest.getParameterMap();
        for (Map.Entry<String,String[]> m:map.entrySet()
             ) {
            System.out.println(" _ " + m.getKey()+ ":" + Arrays.asList( m.getValue()));
        }
        /*  _ username:[atguigu]
            _ password:[123]
            _ interesting:[111, 222]*/

        HttpServletRequest httpServletRequest = (HttpServletRequest) servletRequest;
        String requestURI = httpServletRequest.getRequestURI();
        System.out.println(requestURI);
        String method = httpServletRequest.getMethod();
        System.out.println(method);
        String queryString = httpServletRequest.getQueryString();
        System.out.println(queryString);
        String servletPath = httpServletRequest.getServletPath();
        System.out.println(servletPath);
        /*  /loginServlet
            POST
            null
            /loginServlet*/

      /loginServlet
      GET
      username=atguigu&password=123&interesting=111&interesting=222
      /loginServlet

    }

  

获取请求方式:

HttpServletRequest:是ServletRequest的子接口,针对于HTTP请求所定义,里面包含了大量获取HTTP请求相关的方法

 

2.Servlet-ServletResponse

1)getWriter():返回PrintWriter对象,调用该对象的print()方法,将把print()中的参数直接打印到客户的浏览器上

  PrintWriter printWriter =   servletResponse.getWriter();             

  printWriter.print("HelloWorld...");

2)设置响应的内容类型

servletResponse.setContentType("application/msword");

3)void sendRedirect(String location):请求的重定向(此方法为HttpServletResponse中定义)

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转载自www.cnblogs.com/yangHS/p/10923892.html
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