JavaWeb.servlet基本使用

什么是Servlet

Servlet的生命周期

 Servlet相关的接口

HttpServlet类

 代码过程

package com.zking.servlet;

import java.io.IOException;
import java.io.PrintWriter;

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

public class LoginServlet implements Servlet{

	@Override
	public ServletConfig getServletConfig() {
		//得到配置
		return null;
	}

	@Override
	public String getServletInfo() { 
		//得到信息
		return null;
	}

	@Override
	public void init(ServletConfig arg0) throws ServletException {
		// 初始化 这个servlet被别个访问的
		System.out.println("初始化了");
	}

	@Override
	public void service(ServletRequest req, ServletResponse resp) throws ServletException, IOException {
		// 服务 访问的时候他来提供信息
		//request : 请求 [获取用户带过来的数据]
		//response : 响应 [给用户输出信息]
		
		//乱码
		req.setCharacterEncoding("utf-8");
		//获取信息
		String username = req.getParameter("username");
		String userpwd = req.getParameter("userpwd");
		//获取输出对象
		resp.setCharacterEncoding("gbk");
		PrintWriter out = resp.getWriter();
		//逻辑判断
		if("root".equals(username)&&"root123".equals(userpwd)) {
			//显示在页面中 [登录成功]
			out.print("登录成功");
		}else {
			//显示在页面中 [登录失败]
			out.print("登录失败");
		}
		
	}
	
	@Override
	public void destroy() { 
		//销毁 
		//	1.你更新了servlet代码
		//  2.服务器关闭
		System.out.println("我销毁了");
	}

}

package com.zking.servlet;

import java.io.IOException;
import java.io.PrintWriter;

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("/two.do") //注解式配置
public class LoginTwoServlet extends HttpServlet{

	//提供方法给别个访问才可以
	
	//servlet可以支持多重访问方式
	
	//提供get访问
	protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
		doPost(req, resp);
	}
	
	//提供post访问
	protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
		//拿数据
		String username = req.getParameter("username");
		//alt+1
		String userpwd = req.getParameter("userpwd");
		//获取输出对象
		resp.setCharacterEncoding("gbk");
		PrintWriter out = resp.getWriter();
		//逻辑判断
		if("root".equals(username)&&"root123".equals(userpwd)) {
			//显示在页面中 [登录成功]
			out.print("登录成功");
			// resp.sendRedirect("");
			// req.getRequestDispatcher("").forward(req, resp);
		}else {
			//显示在页面中 [登录失败]
			out.print("登录失败");
		}
		//session
		req.getSession();
		//application
		req.getServletContext();
		//Context 上下文【容器】
	}
	
	
	
}