Servlet创建的方式

一、实现Servlet 接口

package com.openlab;

import java.io.IOException;

import javax.servlet.Servlet;
import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;

public class ServletDemo001 implements Servlet {

	@Override
	public void destroy() {
		System.out.println("我主要用于对servle进行销毁");
	}

	@Override
	public ServletConfig getServletConfig() {
		System.out.println("我主要返回封装了servle配置信息的对象");
		return null;
	}

	@Override
	public String getServletInfo() {
		return "我主要返回servle的相关信息";
	}

	//servlet初始化只有一次
	@Override
	public void init(ServletConfig arg0) throws ServletException {
		System.out.println("我是初始化servlet的方法");
	}

	@Override
	public void service(ServletRequest arg0, ServletResponse arg1) throws ServletException, IOException {
		arg1.setContentType("text/html;charset=UTF-8");
		arg1.getWriter().write("哈哈，我是servlet输出页面的信息");
		System.out.println("主要用于对客户端的请求进行接受并处理...");
		System.out.println(getServletConfig());
		System.out.println(getServletInfo());
	}
}

在web.xml中需要添加的配置

<!-- 配置ServletDemo001的相关配置 -->
	<!-- 1、配置servlet的名字和创建类 -->
	<servlet>
		<servlet-name>firstServlet</servlet-name>
		<servlet-class>com.openlab.ServletDemo001</servlet-class>
	</servlet>
	<!-- 2、配置servlet的路由 -->
	<servlet-mapping>
		<servlet-name>firstServlet</servlet-name>
		<url-pattern>/servletDemo001</url-pattern>
	</servlet-mapping>

在浏览器搜索框中输入 http://localhost:8080/MyWebDemo002/servletDemo001
在这里插入图片描述

二、继承GenericServlet类

package com.openlab;

import java.io.IOException;

import javax.servlet.GenericServlet;
import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;

public class ServletDemo002 extends GenericServlet {

	@Override
	public void service(ServletRequest arg0, ServletResponse arg1) throws ServletException, IOException {
		System.out.println("我是通过继承GenericServlet的方式创建的servlet...");
	}

	@Override
	public void destroy() {
		System.out.println("我是通过继承的方式创建的servlet被销毁了");
	}

	@Override
	public ServletConfig getServletConfig() {
		return super.getServletConfig();
	}

	@Override
	public String getServletInfo() {
		return "我是通过继承方式返回的";
	}

	@Override
	public void init() throws ServletException {
		System.out.println("我是通过继承的初始化");
	}
}

在web.xml中需要添加的配置

	<servlet>
		<servlet-name>secondServlet</servlet-name>
		<servlet-class>com.openlab.ServletDemo002</servlet-class>
	</servlet>
	<servlet-mapping>
		<servlet-name>secondServlet</servlet-name>
		<url-pattern>/servletDemo002</url-pattern>
	</servlet-mapping>

在浏览器搜索框中输入 http://localhost:8080/MyWebDemo002/servletDemo002
在这里插入图片描述

三、继承HttpServlet方法（最常用的方式）

package com.openlab;

import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

@WebServlet("/servletDemo003")	// 可以不创建web.xml，使用注解方式配置也可以。
public class ServletDemo003 extends HttpServlet {

	@Override
	//专门用于处理客户端的get请求，会自动执行
	protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
		System.out.println("我是doGet方法，我正在处理客户端的get请求...");
	}

	@Override
	//专门用于处理客户端的post请求，会自动执行
	protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
		System.out.println("我是doPost方法，我正在处理客户端的post请求...");
	}
}

在web.xml中需要添加的配置

<servlet>
		<servlet-name>threeServlet</servlet-name>
		<servlet-class>com.openlab.ServletDemo003</servlet-class>
	</servlet>
	<servlet-mapping>
		<servlet-name>threeServlet</servlet-name>
		<url-pattern>/servletDemo003</url-pattern>
	</servlet-mapping>