Eclipse中创建并运行Servlet项目

 最近看了写http协议的学习资料，因此想要实现下andriod平台和服务器通信，那就servlet吧，哎哟，还不错哦！顺便说下，我这个servlet服务是想获得用户名和密码进行校验，然后反给客户端状态码；数据库啥的没来得及做，周末时间还是短了点......

    Eclipse的java环境搭建好了
    1.下载tomcat，解压版的，这里我用的是以前下载的apache-tomcat-6.0.35，解压到任意盘=>C:\apache-tomcat-6.0.35；
    2.下载tomcat插件，解压到Eclipse插件目录=>H:\eclipse\plugins目录，启动Eclipse就可以看见小猫了；
    3.Eclipse下的Window->Preferences->Tomcat设置下版本和tomcat主目录，版本别搞错了！省的麻烦...
    
    完成，其实就是这么简单，点击下“启动小猫”就可以启动了，只要没显示什么异常，没显示空指针的log；而是显示了启动时间就ok了；

    4.新建一个tomcat工程，我的是TaxiServlet；
    5.在  TaxiServlet/WEB-INF/src下新建一个包，我的是com.servlet.login；
    6.在包下新建类，我的是LoginAction.java，内容稍后说；
    7.在WEB-INF下新建web.xml文件；

    8.首先LoginAction.java内容可以如下：
    9.web.xml内容：

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 <?xml version="1.0" encoding="utf-8"?>
 <!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>login</servlet-name>    <!-- 名字随便 -->
         <servlet-class>com.servlet.login.LoginAction</servlet-class>    <!-- servlet类名-->
     </servlet>

     <servlet-mapping>
         <servlet-name>login</servlet-name>
         <url-pattern>/login</url-pattern>    <!-- url访问虚拟路径，最后我们就是通过工程名/login进行访问的，像这样http://127.0.0.1:8000/LoginAction/login-->
     </servlet-mapping>

 </web-app>

    这里 我客户端的用户名和密码是通过post请求的，因此doPost方法会被调用；doGet方法可以测试下网页，用http://127.0.0.1:port/servlet工程名称/url-pattern虚拟路径  进行测试；
   
    我的工程：

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 package com.servlet.login;

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

 /**
  * 登录模块校验Servlet
  * @author Administrator
  *
  */
 public class LoginAction extends HttpServlet {
     /**
      *
      */
     private static final long serialVersionUID = 1L;

     public LoginAction()
     {
         super();
     }

     protected void doGet(HttpServletRequest req, HttpServletResponse res)
             throws ServletException, IOException {
         res.setContentType("text/html;charset=utf-8");
         req.setCharacterEncoding("utf-8");
         res.setCharacterEncoding("utf-8");

         PrintWriter out = res.getWriter();
         out.println("Hello, Brave new World!");
         out.close();
     }

     protected void doPost(HttpServletRequest req, HttpServletResponse res)
             throws ServletException, IOException {
         if (null == req)
         {
             return;
         }
         res.setContentType("text/html;charset=utf-8");
         req.setCharacterEncoding("utf-8");
         res.setCharacterEncoding("utf-8");

         PrintWriter out = res.getWriter();
         String username = req.getParameter("user_name");
         String password = req.getParameter("password");
         if (username.equals("admin"))
         {
             if (password.equals("123"))
             {
                 out.println("0");        ///< 正确
             }
             else
             {
                 out.println("2");        ///< 密码错误
             }
         }
         else
         {
             out.println("1");            ///< 用户名错误
         }
         out.flush();
         out.close();
     }
 }

    测试以下： http://127.0.0.1:8000/TaxiServlet/login 
    

    web.xml的详细配置大家可以网上搜搜，我也是经过测试才了解怎么回事的，很多网络并没有说明到底怎么回事？因此对于我这样的初学者总是很疑惑的，相信只有了解了本质才知道，也才能写出好的code...也进步最快,,,,,,
   
    我的doPost方法将用于andriod应用程序登录时校验，数据库校验慢慢完善...先这样
        感谢网友的分享，通过你们我学到了很多东西.... 网友 http://www.linuxidc.com/Linux/2012-06/63935.htm ，其它就不举例了，嘿嘿...


    对了还要说下tomcat的配置，不然可能会出现404错误；C:\apache-tomcat-6.0.35\conf\tomcat-users.xml文件一般来说默认用户配置都是注释着的，你需要配置至少一个用户，我的如下：

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 <?xml version='1.0' encoding='utf-8'?>
 <!--
   Licensed to the Apache Software Foundation (ASF) under one or more
   contributor license agreements. See the NOTICE file distributed with
   this work for additional information regarding copyright ownership.
   The ASF licenses this file to You under the Apache License, Version 2.0
   (the "License"); you may not use this file except in compliance with
   the License. You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.
 -->
 <tomcat-users>
 <!--
   NOTE: By default, no user is included in the "manager-gui" role required
   to operate the "/manager/html" web application. If you wish to use this app,
   you must define such a user - the username and password are arbitrary.
 -->
 <!--
   NOTE: The sample user and role entries below are wrapped in a comment
   and thus are ignored when reading this file. Do not forget to remove
   <!.. ..> that surrounds them.
 -->
 <!--
   <role rolename="tomcat"/>
   <role rolename="role1"/>
   <role rolename="manager"/>
   <user username="admin" password="admin" roles="manager"/>
   <user username="tomcat" password="tomcat" roles="tomcat"/>
   <user username="both" password="tomcat" roles="tomcat,role1"/>
   <user username="role1" password="tomcat" roles="role1"/>
 -->
     <role rolename="manager"/>
   <user username="admin" password="admin" roles="manager"/>
 </tomcat-users>

    其它的根据需要来吧....

    配置端口号：
     C:\apache-tomcat-6.0.35\conf\ server.xml用来配置端口号，如果你电脑安装了n多软件，可能默认的8080端口无法使用，记得进去找到它，改改哈！多练习练习就熟了，，，编程也是写字..