Servlet入门（第一个Servlet的Web程序）

新建maven项目，注意项目的类型

 

project名为ServletExample

 

点击Finish。建立maven项目完毕例如以下

 

生成后的文件夹没有java源代码文件夹。依照maven的约定，还要新建src/main/java的源代码文件夹。选中项目，点击鼠标右键

 

不知道为什么，新建src/main/java文件夹时。eclipse报这个文件夹已经存在。

没办法，先建立src/main/java2。然后再重构为src/main/java

 

 

配置maven的构建文件pom.xml

<?xml version="1.0" encoding="UTF-8"?>

<projectxmlns="http://maven.apache.org/POM/4.0.0"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

       xsi:schemaLocation="http://maven.apache.org/POM/4.0.0http://maven.apache.org/maven-v4_0_0.xsd">

       <modelVersion>4.0.0</modelVersion>

       <packaging>war</packaging>

       <name>ServletExample</name>

       <groupId>com.ydoing</groupId>

       <artifactId>ServletExample</artifactId>

       <version>0.0.1-SNAPSHOT</version>

 

       <build>

              <plugins>

                    <plugin>

                           <groupId>org.apache.maven.plugins</groupId>

                           <artifactId>maven-compiler-plugin</artifactId>

                           <version>3.1</version>

                           <configuration>

                                  <source>1.7</source>

                                  <target>1.7</target>

                           </configuration>

                    </plugin>

              </plugins>

       </build>

       <dependencies>

              <dependency>

                    <groupId>javax.servlet</groupId>

                    <artifactId>javax.servlet-api</artifactId>

                    <version>3.0.1</version>

              </dependency>

       </dependencies>

 

</project>

更新maven项目

新增HelloServlet

 

代码例如以下，该类核心代码是doGet，作用是向client返回“Hello, world!”

package com.ydoing.helloapp;

 

import java.io.IOException;

import java.io.PrintWriter;

 

import javax.servlet.ServletException;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

 

/**

 * Servletimplementation class HelloServlet

 */

publicclassHelloServletextendsHttpServlet{

       privatestaticfinallongserialVersionUID =1L;

      

    /**

     * @see HttpServlet#HttpServlet()

     */

    publicHelloServlet(){

        super();

        // TODO Auto-generated constructor stub

    }

 

       /**

        * @see HttpServlet#doGet(HttpServletRequestrequest, HttpServletResponse response)

        */

       protectedvoid doGet(HttpServletRequest request,HttpServletResponse response)throwsServletException,IOException{

              // TODO Auto-generated method stub

              response.setContentType("text/html");

              PrintWriter out = response.getWriter();

              String msg ="Hello, world!";

              out.println("<h1>"+ msg +"</h1>");

       }

 

       /**

        * @see HttpServlet#doPost(HttpServletRequestrequest, HttpServletResponse response)

        */

       protectedvoid doPost(HttpServletRequest request,HttpServletResponse response)throwsServletException,IOException{

              // TODO Auto-generated method stub

       }

 

}

改动web.xml文件。作用是将URI映射到指定的Servlet上

<?

xml version="1.0" encoding="UTF-8"?>

<web-appxmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

       xmlns="http://java.sun.com/xml/ns/javaee"

       xsi:schemaLocation="http://java.sun.com/xml/ns/javaeehttp://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"

       id="WebApp_ID"version="3.0">

 

       <servlet>

              <servlet-name>HelloServlet</servlet-name>

              <servlet-class>com.ydoing.helloapp.HelloServlet</servlet-class>

       </servlet>

       <servlet-mapping>

              <servlet-name>HelloServlet</servlet-name>

              <url-pattern>/hello</url-pattern>

       </servlet-mapping>

 

</web-app>

执行在Tomcat上

 

执行结果例如以下