7.04.4 request遍历所有键值对与response回写图片

req.getParameterValues()
request遍历所有键值对与response回写图片

@WebServlet("/zhuanfa1")
public class ZhuanFa1Servlet extends HttpServlet {
    //windows.href.location=
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        System.out.println("ZhuanFa1Servlet.doGet");
        //如何接收前端多个键相同的参数
//        String[] hobbies = req.getParameterValues("hobby");
//        System.out.println("Arrays.toString(hobbies) = " + Arrays.toString(hobbies));
        Map<String, String[]> parameterMap = req.getParameterMap();
        Set<String> keySet = parameterMap.keySet();
        for (String key : keySet) {
            System.out.println("key = " + key);
            System.out.println("Arrays.toString(parameterMap.get(key)) = " + Arrays.toString(parameterMap.get(key)));
        }
        Enumeration<String> headerNames = req.getHeaderNames();
        while (headerNames.hasMoreElements()) {
            String headerName = headerNames.nextElement();
            String headerValue = req.getHeader(headerName);
            System.out.println("headerName = " + headerName);
            System.out.println("headerValue = " + headerValue);
        }
        req.setAttribute("myZhuanfa", "helloZhuanFa");
        req.removeAttribute("myZhuanfa");
        //请求转发到/zhuanfa2
        req.getRequestDispatcher("/zhuanfa2").forward(req,resp);
    }

//localhost:8080/mavenDemo01/baidu
@WebServlet("/zhuanfa2")
public class ZhuanFa2Servlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        System.out.println("ZhuanFa2Servlet.doGet");
        String username = req.getParameter("username");
        System.out.println("username = " + username);
        Object myZhuanfa = req.getAttribute("myZhuanfa");
        System.out.println("myZhuanfa = " + myZhuanfa);
        resp.getWriter().write("<img src=\"http://localhost:8080/mavenDemo01/123.jpg\">");
    }