servlet基本使用

其他 2018-10-12 22:10:06 阅读次数: 0
版权声明：本文为博主原创文章，未经博主允许不得转载。 https://blog.csdn.net/weixin_38323645/article/details/82928170

文章目录

1 helloWorld

package action;
import java.io.PrintWriter;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * Servlet implementation class HelloWorldServlet
 */

public class HelloWorldServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;
	@Override
	protected void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		System.out.println("get");
		this.doPost(request, response);
	}

	@Override
	protected void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		response.setCharacterEncoding("gbk");
		PrintWriter out=response.getWriter();
		out.println("<html>");
		out.println("<head><title>问候大爷</title></head>");
		out.println("Servlet大爷你好！");
		out.println("</html>");
		out.close();
	}

}


  <servlet>
    <servlet-name>helloWorldServlet</servlet-name>
    <servlet-class>action.HelloWorldServlet</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>helloWorldServlet</servlet-name>
    <url-pattern>/helloWorld</url-pattern>
  </servlet-mapping>

在这里插入图片描述

2 servlet生命周期

servlet类加载—>实例化—>服务—>销毁。
加载–>init()—>service()–>destroy()
Init()只会执行一次

package action;

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class LifeServlet extends HttpServlet{

	private static final long serialVersionUID = 1L;

	@Override
	protected void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		System.out.println("service");
	}

	@Override
	protected void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		System.out.println("service");
	}

	@Override
	public void destroy() {
		System.out.println("servlet销毁");
	}

	@Override
	public void init() throws ServletException {
		System.out.println("servlet初始化");
	}
}

 <servlet>
    <servlet-name>lifeServlet</servlet-name>
    <servlet-class>action.LifeServlet</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>lifeServlet</servlet-name>
    <url-pattern>/life</url-pattern>
  </servlet-mapping>

在这里插入图片描述

3 转发和重定向

转发
在这里插入图片描述
在这里插入图片描述
在这里插入图片描述
重定向：
在这里插入图片描述
在这里插入图片描述

4 Servlet简单登录

工具类

package util;

import java.sql.Connection;
import java.sql.DriverManager;

public class DbUtil {
	private String dbUrl="jdbc:oracle:thin:@localhost:1521:orcl";
	private String dbUserName="envir";
	private String dbPassword="1";
	private String jdbcName="oracle.jdbc.driver.OracleDriver";
	
	//连接
	public Connection getCon()throws Exception{
		Class.forName(jdbcName);
		Connection con=DriverManager.getConnection(dbUrl, dbUserName, dbPassword);
		return con;
	}
	//关闭
	public void closeCon(Connection con)throws Exception{
		if(con!=null){
			con.close();
		}
	}
	//连接测试
	public static void main(String[] args) {
		DbUtil dbUtil=new DbUtil();
		try {
			dbUtil.getCon();
			System.out.println("连接成功");
		} catch (Exception e) {
			e.printStackTrace();
		}
	}
}

实体类

package po;
public class User {
	private int id;
	private String userName;
	private String password;
	public User() {
		super();
	}
	public User(String userName, String password) {
		super();
		this.userName = userName;
		this.password = password;
	}
	public int getId() {
		return id;
	}
	public void setId(int id) {
		this.id = id;
	}
	public String getUserName() {
		return userName;
	}
	public void setUserName(String userName) {
		this.userName = userName;
	}
	public String getPassword() {
		return password;
	}
	public void setPassword(String password) {
		this.password = password;
	}
}

login.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
<form action="login" method="post">
<table>
	<tr>
		<th colspan="2">用户登录</th>
	</tr>
	<tr>
		<td>用户名：</td>
		<td><input type="text" id="userName" name="userName" value="${userName }"/></td>
	</tr>
	<tr>
		<td>密码：</td>
		<td><input type="password" id="password" name="password" value="${password }"/></td>
	</tr>
	<tr>
		<td><input type="submit" value="登录"/></td>
		<td><font color="red">${error }</font></td>
	</tr>
</table>
</form>
</body>
</html>

dao

package dao;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;

import po.User;


public class UserDao {

	public User login(Connection con,User user)throws Exception{
		User resultUser=null;
		String sql="select * from t_user where userName=? and password=?";
		try{
		PreparedStatement pstmt=con.prepareStatement(sql);
		pstmt.setString(1, user.getUserName());
		pstmt.setString(2, user.getPassword());
		ResultSet rs=pstmt.executeQuery();
		if(rs.next()){
			resultUser=new User();
			resultUser.setUserName(rs.getString("userName"));
			resultUser.setPassword(rs.getString("password"));
		}
		}catch(Exception e){
			e.printStackTrace();
		}
		return resultUser;
	}
			
}

controller

package controller;

import java.io.IOException;
import java.sql.Connection;

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

import po.User;
import dao.UserDao;
import util.DbUtil;


public class LoginServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;
       
	DbUtil dbUtil=new DbUtil();
	UserDao userDao=new UserDao();

	@Override
	protected void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		this.doPost(request, response);
	}
	/**
	 * servlet 简单登录
	 */
	protected void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		String userName=request.getParameter("userName");
		String password=request.getParameter("password");
		
		Connection con=null;
		try {
			User user=new User(userName,password);
			con=dbUtil.getCon();
			User currentUser=userDao.login(con, user);
			if(currentUser==null){
				request.setAttribute("error", "用户名或密码错误");
				request.setAttribute("userName", userName);
				request.setAttribute("password", password);
				request.getRequestDispatcher("login.jsp").forward(request, response);
			}else{
				HttpSession session=request.getSession();//用户名密码正确保存在session中并显示在main.jsp页面
				session.setAttribute("currentUser", currentUser);
				response.sendRedirect("main.jsp");
			}
		} catch (Exception e) {
			e.printStackTrace();
		}
	}

}

main.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
主页！当前登录用户：${currentUser.userName } &nbsp;&nbsp;<a href="logout">注销</a>
</body>
</html>

在这里插入图片描述
登出的控制层

package controller;

import java.io.IOException;
import java.sql.Connection;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

import dao.UserDao;
import po.User;
import util.DbUtil;

public class LogoutServlet extends HttpServlet{
	private static final long serialVersionUID = 1L;
	@Override
	protected void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		this.doPost(request, response);
	}
	@Override
	protected void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		request.getSession().invalidate();//清除session
		response.sendRedirect("login.jsp");
	}
}

5 Servlet 过滤器

过滤器controller

package filter;
import java.io.IOException;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpSession;
//登录过滤  过滤器
public class LoginFilter implements Filter{
	public void destroy() {//当从Tomcat中移除这个项目时执行此方法
		System.out.println("destroy");

	}
	public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse,
			FilterChain filterChain) throws IOException, ServletException {
		//编码过滤
		servletRequest.setCharacterEncoding("utf-8");
		servletResponse.setContentType("text/html;charset=utf-8");
		servletResponse.setCharacterEncoding("utf-8");
		
		HttpServletRequest request=(HttpServletRequest)servletRequest;
		HttpSession session=request.getSession();
		Object object=session.getAttribute("currentUser");//从session中获取用户
		String path=request.getServletPath();
		if(object==null&&path.indexOf("login")<0){//如果session中没有用户且当前路径不是从登录页login.jsp进来则让他跳到登录页
			request.getRequestDispatcher("login.jsp").forward(servletRequest, servletResponse);
		}else{
			//继续做原本访问网页的事情
			filterChain.doFilter(servletRequest, servletResponse);
		}
	}
	//配置过滤器后 Tomcat启动 会先执行此方法
	public void init(FilterConfig filterConfig) throws ServletException {
		System.out.println("init");

	}
}


<filter>
    <filter-name>loginFilter</filter-name>
    <filter-class>filter.LoginFilter</filter-class>
  </filter>
  <filter-mapping>
    <filter-name>loginFilter</filter-name>
    <url-pattern>/*</url-pattern>
  </filter-mapping>

6 Servlet 监听器

监听 web 事件；如 application,session,request

package listener;
import javax.servlet.http.HttpSessionAttributeListener;
import javax.servlet.http.HttpSessionBindingEvent;
//session监听器 
public class SessionAttributeListener implements HttpSessionAttributeListener{
	/**
	 * 当有设置 session时候，监听一下             (登录成功时候， 设置了session  所以用户在登录成功是就能监听到)
	 */
	public void attributeAdded(HttpSessionBindingEvent httpSessionBindingEvent) {
		// TODO Auto-generated method stub
		System.out.println("session添加监听,添加的属性名："+httpSessionBindingEvent.getName()+","
				+ "属性值："+httpSessionBindingEvent.getValue());
	}

	public void attributeRemoved(HttpSessionBindingEvent httpSessionBindingEvent) {
		// TODO Auto-generated method stub
		System.out.println("session删除监听,删除的属性名："+httpSessionBindingEvent.getName()+
				",属性值："+httpSessionBindingEvent.getValue());
	}

	public void attributeReplaced(HttpSessionBindingEvent httpSessionBindingEvent) {
		// TODO Auto-generated method stub
		
	}

}

在这里插入图片描述

猜你喜欢

转载自blog.csdn.net/weixin_38323645/article/details/82928170
今日推荐
周排行
(BIND最佳实践)Linux运维最佳实践
makefile ifeq之坑: 1. syntax error near unexpected token 2. *** missing separator. Stop.
easyui datagrid操作栏内置图片按钮
SQLyog连接MySQL时出现的2058错误解决方法
linux音频开发
hashcode方法 简析
SpringBoot中使用Transaction注解遇到的坑
逆战-CSS中子元素在父元素中的4种水平垂直居中方法
Expression.Blend.4 Chapter 图片和视频的使用
springMVC返回void值
每日归档
更多
2024-09-17(0)
2024-09-16(0)
2024-09-15(0)
2024-09-14(0)
2024-09-13(0)
2024-09-12(0)
2024-09-11(0)
2024-09-10(0)
2024-09-09(0)
2024-09-08(0)

代码天地 © 2018 codetd.com

境外服务器   最新电视剧2022