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  • 用response输出一个验证码

    package servlet;
    
    import java.io.IOException;
    import java.io.PrintWriter;
    
    import javax.servlet.ServletException;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    
    public class FirstServlet extends HttpServlet {
    
        /**
         * Constructor of the object.
         */
        public FirstServlet() {
            super();
        }
    
        /**
         * Destruction of the servlet. <br>
         */
        public void destroy() {
            super.destroy(); // Just puts "destroy" string in log
            // Put your code here
        }
    
        /**
         * The doGet method of the servlet. <br>
         *
         * This method is called when a form has its tag value method equals to get.
         * 
         * @param request the request send by the client to the server
         * @param response the response send by the server to the client
         * @throws ServletException if an error occurred
         * @throws IOException if an error occurred
         */
        public void doGet(HttpServletRequest request, HttpServletResponse response)
                throws ServletException, IOException {
            this.execute(request,response);
        }
    
        /**
         * The doPost method of the servlet. <br>
         *
         * This method is called when a form has its tag value method equals to post.
         * 
         * @param request the request send by the client to the server
         * @param response the response send by the server to the client
         * @throws ServletException if an error occurred
         * @throws IOException if an error occurred
         */
        public void doPost(HttpServletRequest request, HttpServletResponse response)
                throws ServletException, IOException {
            this.execute(request,response);
        }
    
        /**
         * Initialization of the servlet. <br>
         *
         * @throws ServletException if an error occurs
         */
        public void execute(HttpServletRequest request,HttpServletResponse response)
            throws ServletException,IOException
        {
            this.log("则行doget方法");
            response.setCharacterEncoding("UTF-8");
            request.setCharacterEncoding("UTF-8");
            String requestURI=request.getRequestURI();
            String method=request.getMethod();
            String param=request.getParameter("param");
            response.setContentType("text/html");
            PrintWriter out = response.getWriter();
            out.println("<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">");
            out.println("<HTML>");
            out.println("  <HEAD><TITLE>A Servlet</TITLE></HEAD>");
            out.println("  <BODY>");
            out.println(method+"方式访问该页面。取到的para参数是"+param+"<br/>");
            out.println("<form action='"+requestURI+"'method='post'><input type='text' name='qqq' value='param string'><input type='submit' value='用post方式查询"+requestURI+"'></form>");
            out.println("<script>document.write('本页面最后更新时间'+document.lastModified);</script>");
            out.println("  </BODY>");
            out.println("</HTML>");
            out.flush();
            out.close();
        }
        public void init() throws ServletException {
            // Put your code here
        }
    
    }
    View Code
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  • 原文地址:https://www.cnblogs.com/vhyc/p/6220814.html
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