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  • hello1以及hello2的部分代码分析

    (一)1.GreetingServlet.java源码文件:

    @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源码文件:

    @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.";

    }
    }

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  • 原文地址:https://www.cnblogs.com/cducz/p/10591329.html
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