Analisis of Hello2 source

GreetingServlet.java

@WebServlet("/greeting")   //为servelt指定URL pattern为:/greetingpublic class GreetingServlet extends HttpServlet {    @Override              //注解,对子类的方法进行重写    public void doGet(HttpServletRequest request,   //扩展HttpServelt,重写doGet方法            HttpServletResponse response)            throws ServletException, IOException {        response.setContentType("text/html");         //指定响应页面的类型为html        response.setBufferSize(8192);                   //指定缓冲区的大小        try (PrintWriter out = response.getWriter()) {        //实例化对象out,作为向html页面输出的对象            //使用println属性,向html页面输出html标签,这里输出的是:            //<html lang=en>            //<head>            //    <title>Servelt Hello</title>            //</head>            out.println("<html lang=\"en\">"                    + "<head><title>Servlet Hello</title></head>");            // then write the data of the response            //使用println属性,向html页面输出html标签,这里输出的是:            //<body bgcolor=#ffffff>            //<img scr=resources/images/duke.waving.gif alt=Duke waving his hand>            //<form method=get>            //    <h2>Hello,My name is Duke.What's yours?</h2>            //    <input title=My name is: type=text name=username size=25>            //    <p></p>            //    <input type=submit value=Submit/>            //    <input type=result value=Reset/>            //</form>            out.println("<body  bgcolor=\"#ffffff\">"                    + "<img src=\"resources/images/duke.waving.gif\" "                    + "alt=\"Duke waving his hand\">"                    + "<form method=\"get\">"                    + "<h2>Hello, my name is Duke. What's yours?</h2>"                    + "<input title=\"My name is: \" type=\"text\" "                    + "name=\"username\" size=\"25\"/>"                    + "<p></p>"                    + "<input type=\"submit\" value=\"Submit\"/>"                    + "<input type=\"reset\" value=\"Reset\"/>"                    + "</form>");            //将抓取到的username的值赋给一个字符串username,获取input标签内的username值            String username = request.getParameter("username");            if (username != null && username.length() > 0) {                RequestDispatcher dispatcher =                        getServletContext().getRequestDispatcher("/response");                        //指定要跳转的页面相对于上下文根的URL pattern为/response                if (dispatcher != null) {                    //整合request、response然后跳转                    dispatcher.include(request, response);                }            }            //使用println属性,向html页面输出HTML标签,这里输出的是:            //    </body>            //</html>            out.println("</body></html>");        }    }    @Override    public String getServletInfo() {        return "The Hello servlet says hello.";    }}

ResponseServelt.java

@WebServlet("/response")        //注释指定相对于上下文根的URL模式为:/responsepublic class ResponseServlet extends HttpServlet {    @Override    public void doGet(HttpServletRequest request,    //该servelt重写改doGet方法,实现Get HTTP方法            HttpServletResponse response)            throws ServletException, IOException {        try (PrintWriter out = response.getWriter()) {           //实例化对象out,作为html页面输出的对象            //接受来自greeting页面请求中的input标签中的username输入            String username = request.getParameter("username");            if (username != null && username.length() > 0) {                //使用println属性,向html页面输出html标签,这里输出的是:                //<h2>Helelo," + username + "!</h2>                out.println("<h2>Hello, " + username + "!</h2>");            }        }    }    @Override    public String getServletInfo() {        return "The Response servlet says hello.";    }}