JavaWeb学习笔记——开发动态WEB资源（四）打印当前使用的是get方法

该工程的名称是testhttp，功能是在页面中表格打印浏览过程中的相关头信息。
　　新建一个工程，然后在这个工程里面新建一个servlet，这样便可以省去编写web.xml的过程
以下是TestHttpServlet.java中的代码
package org.common.servlet;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.Enumeration;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class TestHttpServlet extends HttpServlet {

    /**
     * Constructor of the object.
     */
    public TestHttpServlet() {
        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
     */
    
    //Servlet接口的参数service(ServletRequest arg0, ServletResponse arg1)
    
    //HttpServletRequest封装了所有的请求信息，其实就是Tomcat将请求信息按照JAVA EE的Servlet的规范
    //封装好给我们
    
    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        
        //设置返回类型
        //response.setContentType("text/html;charset=GBK");
        response.setContentType("text/html");
        response.setCharacterEncoding("GBK");
        
        //获取输出流
        PrintWriter out = response.getWriter();
        out.println("<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">");
        out.println("<HTML>");
        out.println("  <HEAD><TITLE>testhttp Servlet</TITLE></HEAD>");
        out.println("  <BODY>");
        
        out.print("<center>");
        out.print(" <h2>请求头信息列表<h2> ");
        
        out.print(" <table border=1> ");
        out.print(" <tr><th>名字</th><th>值</th></tr> ");
        //返回头消息名字集合，返回的是一个枚举
        Enumeration enums = request.getHeaderNames();
        //遍历获取所有头信息名和值
        while(enums.hasMoreElements()){
            //获取每一个头消息的名字
            String headName = (String)enums.nextElement();
            out.println(" <tr> ");
            out.println(" <td> " + headName + " </td> ");
            //getHeader(java.lang.String name) 
            //Returns the value of the specified request header as a String.
            //返回这个名字的头信息的值
            out.println(" <td> " + request.getHeaders(headName) + " </td> ");
            out.println(" </tr> ");
        }
        out.println(" </table> ");
        
        out.println(" <hr> ");
        //测试HttpServletRequest的方法
        out.println("Method： " + request.getMethod() + "<br>");
        out.println("Request URI： " + request.getRequestURI() + "<br>");
        out.println("Protocol： " + request.getProtocol() + "<br>");
        out.println("PathInfo： " + request.getPathInfo() + "<br>");
        out.println("Remote Address： " + request.getRemoteAddr() + "<br>");
        out.println("ContextPath： " + request.getContextPath() + "<br>");
        out.println("getScheme： " + request.getScheme() + "<br>");
        out.println("getServerName： " + request.getServerName() + "<br>");
        out.println("getServerPort： " + request.getServerPort() + "<br>");
        out.println("getRequestURI： " + request.getRequestURI() + "<br>");
        String path = request.getContextPath();
        //请求全路径
        String basePath
            = request.getScheme() + "://" + request.getServerName() + ":"
            + request.getServerPort() + request.getRequestURI();
        out.println(" path: " + path + "<br>");
        out.println(" basePath: " + basePath + "<br>");
        
        //out.print(this.getClass());
        //out.println(", using the GET method");
        
        out.print("</center>");
        out.println("  </BODY>");
        out.println("</HTML>");
        out.flush();
        out.close();
    }

    /**
     * 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 {
        
        //调用doGet方法
        this.doGet(request, response);
    }

    /**
     * Initialization of the servlet. <br>
     *
     * @throws ServletException if an error occurs
     */
    public void init() throws ServletException {
        // Put your code here
    }

}
然后部署并启动Tomcat服务器，在浏览器中输入http://127.0.0.1:8080/testhttp/servlet/TestHttpServlet