重新学习Servlet

package javax.servlet;

import java.io.IOException;

public interface Servlet {

    public void init(ServletConfig config) throws ServletException;
  
    public ServletConfig getServletConfig();

    public void service(ServletRequest req, ServletResponse res)
	throws ServletException, IOException;

    public String getServletInfo();

    public void destroy();
}

public abstract class GenericServlet implements Servlet, ServletConfig, java.io.Serializable

package com.xh.test.api;

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

/**
 * Created by root on 17-11-12.
 */
public class MyGenericServlet extends GenericServlet {
    public void service(ServletRequest req, ServletResponse res) throws ServletException, IOException {
        System.out.println(">>>service " + req + " , " + res);
        String id = req.getParameter("id");
        System.out.println(">>>id " + id);
        res.getWriter().write("hello i am MyGenericServlet");
        res.flushBuffer();

    }

    @Override
    public void init(ServletConfig config) throws ServletException {
        System.out.println(">>>init_p :" + config);
        super.init(config);
    }

    @Override
    public void init() throws ServletException {
        System.out.println(">>>init");
        super.init();
    }

    @Override
    public void destroy() {
        System.out.println(">>>destroy");
        super.destroy();
    }

    public MyGenericServlet() {
        System.out.println(">>>MyGenericServlet");
    }
}

访问：http://localhost:8080/testservlet/1?id=100

浏览器输出：hello i am MyGenericServlet

控制台输出：

>>>MyGenericServlet
>>>init_p :org.apache.catalina.core.StandardWrapperFacade@4a1957bf
>>>init
>>>service org.apache.catalina.connector.RequestFacade@e4f73de , org.apache.catalina.connector.ResponseFacade@297fd904
>>>id 100

PS:容器启动的时候没有初始化，第一次访问才初始化。init(ServletConfig config)的参数由容器传入。ServletConfig包括当前Servlet的名字，服务器监听的地址等

配置文件：

web.xml:

<!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>
    <display-name>Archetype Created Web Application</display-name>
    <servlet>
        <servlet-name>MyGenericServlet</servlet-name>
        <servlet-class>com.xh.test.api.MyGenericServlet</servlet-class>
    </servlet>

    <servlet-mapping>
        <servlet-name>MyGenericServlet</servlet-name>
        <url-pattern>/1</url-pattern>
    </servlet-mapping>
</web-app>

 pom.xml:

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>com.xh.test.servlet</groupId>
    <artifactId>testservlet</artifactId>
    <packaging>war</packaging>
    <version>1.0-SNAPSHOT</version>
    <name>testservlet Maven Webapp</name>
    <url>http://maven.apache.org</url>
    <dependencies>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>3.8.1</version>
            <scope>test</scope>
        </dependency>

        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <version>3.1.0</version>
            <scope>provided</scope>
        </dependency>

    </dependencies>
    <build>
        <plugins>
            <!-- 本地环境使用 -->
            <plugin>
                <groupId>org.apache.tomcat.maven</groupId>
                <artifactId>tomcat7-maven-plugin</artifactId>
                <version>2.1</version>
                <configuration>
                    <hostName>localhost</hostName>    <!--   Default: localhost -->
                    <port>8080</port>    <!-- 启动端口 Default:8080 -->
                    <path>/${project.artifactId}</path>    <!-- 访问应用路径  Default: /${project.artifactId}-->
                    <uriEncoding>UTF-8</uriEncoding>      <!-- uri编码 Default: ISO-8859-1 -->
                </configuration>
            </plugin>
        </plugins>
        <finalName>testservlet</finalName>
    </build>

</project>