Servlet入门（第一个Servlet的Web程序）

新建maven项目，注意项目的类型





工程名为ServletExample





点击Finish，建立maven项目完成如下







生成后的目录没有java源码目录，按照maven的约定，还要新建src/main/java的源码目录。选中项目，点击鼠标右键





不知道为什么，新建src/main/java目录时，eclipse报这个目录已经存在。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





代码如下，该类核心代码是doGet，作用是向客户端返回“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

}



}



修改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>



运行在Tomcat上







运行结果如下