《Servlet与JSP核心编程第二版》阅读记录003-第二个与第三个servlet示例程序

来源：互联网发布：新手怎么装修淘宝店铺编辑：程序博客网时间：2024/04/29 20:22

在测试第二个与第三个程序时发现与书上情况不完全一样，有两方面情况要注意：

1 需要加上 doGet()方法

2 在地址栏中不需要输入 coreservlets.

3 程序代码 coreservlets.HelloServlet2.java

package coreservlets;

import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;

public class HelloServlet2 extends HttpServlet {
public void doGet(HttpServletRequest request,
                    HttpServletResponse response)
      throws ServletException, IOException {
    response.setContentType("text/html");
    PrintWriter out = response.getWriter();
    String docType =
      "<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.0 " +
      "Transitional//EN\">\n";
    out.println(docType +
                "<HTML>\n" +
                "<HEAD><TITLE>Hello (2)</TITLE></HEAD>\n" +
                "<BODY BGCOLOR=\"#FDF5E6\">\n" +
                "<H1>Hello coreservlets.HelloServlet2 cuigh</H1>\n" +
               new java.util.Date() +
                "</BODY></HTML>");
}
/**
*特别说明：下面代码 doPost()方法，原书代码中无，运行环境：360浏览器7.1
如果不加上，会提示：
HTTP Status 404 - /HelloServlet3

type Status report

message /HelloServlet3

description The requested resource (/HelloServlet3) is not available.

Apache Tomcat/4.1.24
*/
public void doPost(HttpServletRequest request,HttpServletResponse response)
   throws ServletException,IOException
{
        this.doGet(request,response);
}

}
4 程序代码 coreservlets.HelloServlet3.java

package coreservlets;

import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;

/** Simple servlet for testing the use of packages
* and utilities from the same package.
* <P>
* Taken from Core Servlets and JavaServer Pages 2nd Edition
* from Prentice Hall and Sun Microsystems Press,
* http://www.coreservlets.com/.
* © 2003 Marty Hall; may be freely used or adapted.
*/

public class HelloServlet3 extends HttpServlet {
public void doGet(HttpServletRequest request,
                    HttpServletResponse response)
      throws ServletException, IOException {
    response.setContentType("text/html");
    PrintWriter out = response.getWriter();
    String title = "Hello (3) coreservlets.HelloServlet3 cuigh";
    out.println(ServletUtilities.headWithTitle(title) +
                "<BODY BGCOLOR=\"#FDF5E6\">\n" +
                "<H1>" + title + "</H1>\n" +
               new java.util.Date() +
                "</BODY></HTML>");
}
/**
*特别说明：下面代码 doPost()方法，原书代码中无，运行环境：360浏览器7.1
如果不加上，会提示：
HTTP Status 404 - /HelloServlet3

type Status report

message /HelloServlet3

description The requested resource (/HelloServlet3) is not available.

Apache Tomcat/4.1.24
*/
public void doPost(HttpServletRequest request,HttpServletResponse response)
   throws ServletException,IOException
{
        this.doGet(request,response);
}
}

5 配置文件 web.xml

<?xml version="1.0" encoding="ISO-8859-1"?>
<!DOCTYPE web-app
    PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
    "http://java.sun.com/dtd/web-app_2_3.dtd">

<web-app>

<servlet>
    <servlet-name>HelloServlet</servlet-name>
    <servlet-class>HelloServlet</servlet-class>
</servlet>
<servlet>
    <servlet-name>HelloServlet2</servlet-name>
    <servlet-class>coreservlets.HelloServlet2</servlet-class>
</servlet>
<servlet>
    <servlet-name>HelloServlet3</servlet-name>
    <servlet-class>coreservlets.HelloServlet3</servlet-class>
</servlet>

<servlet-mapping>
    <servlet-name>HelloServlet</servlet-name>
    <url-pattern>/Helloservlet</url-pattern>
</servlet-mapping>
<servlet-mapping>
    <servlet-name>HelloServlet2</servlet-name>
    <url-pattern>/Helloservlet2</url-pattern>
</servlet-mapping>
<servlet-mapping>
    <servlet-name>HelloServlet3</servlet-name>
    <url-pattern>/Helloservlet3</url-pattern>
</servlet-mapping>

</web-app>

6 地址栏中输入：

http://127.0.0.1:8080/Helloservlet

Hello Servlet! cuigh

Wed Aug 26 17:29:07 CST 2015

http://127.0.0.1:8080/Helloservlet2

Hello coreservlets.HelloServlet2 cuigh

Wed Aug 26 17:34:36 CST 2015

http://127.0.0.1:8080/Helloservlet3

Hello (3) coreservlets.HelloServlet3 cuigh

Wed Aug 26 17:35:00 CST 2015

0 0