hello2应用程序是一个web模块，它使用Java Servlet技术来显示问候和响应。此应用程序的源代码位于 _tut-install_/examples/web/servlet/hello2/目录中。
GreetingServlet.java
/** * Copyright (c) 2014 Oracle and/or its affiliates. All rights reserved. * * You may not modify, use, reproduce, or distribute this software except in * compliance with the terms of the License at: * https://github.com/javaee/tutorial-examples/LICENSE.txt */ package javaeetutorial.hello2; import java.io.IOException; import java.io.PrintWriter; import javax.servlet.RequestDispatcher; import javax.servlet.ServletException; import javax.servlet.annotation.WebServlet; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; @WebServlet("/greeting") //以@WebServlet注释开头，注释指定相对于上下文根的URL模式，即在根目录下使用/greeting来访问 public class GreetingServlet extends HttpServlet { @Override public void doGet(HttpServletRequest request, //该servlet重写该doGet方法，实现GET HTTP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>Servlet Hello</title> // </head> out.println("<html lang="en">" + "<head><title>Servlet Hello</title></head>"); //使用println属性，向html页面输出html标签,这里输出的是： //<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>) 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>"); //使用一个字符串username来获取，第一个input标签内的username的值 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模式为/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."; } }
ResponseServlet.java
/** * Copyright (c) 2014 Oracle and/or its affiliates. All rights reserved. * * You may not modify, use, reproduce, or distribute this software except in * compliance with the terms of the License at: * https://github.com/javaee/tutorial-examples/LICENSE.txt */ package javaeetutorial.hello2; import java.io.IOException; import java.io.PrintWriter; import javax.servlet.ServletException; import javax.servlet.annotation.WebServlet; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; @WebServlet("/response") //以@WebServlet注释开头，注释指定相对于上下文根的URL模式， //即在根目录下使用/response来访问,这里作为greting页面的响应页面来实现访问 public class ResponseServlet extends HttpServlet { @Override public void doGet(HttpServletRequest request, ////该servlet重写该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,作为向html页面输出的对象 //接收来自greting页面请求中的input标签中输入的username 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>Hello,XXX(前面输入的username的值)!</h2> out.println("<h2>Hello, " + username + "!</h2>"); } } } @Override public String getServletInfo() { return "The Response servlet says hello."; } }