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servlet基本使用

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>

servlet基本使用-LMLPHP

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>

servlet基本使用-LMLPHP

3 转发和重定向

转发
servlet基本使用-LMLPHP
servlet基本使用-LMLPHP
servlet基本使用-LMLPHP
重定向：
servlet基本使用-LMLPHP
servlet基本使用-LMLPHP

4Servlet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>

servlet基本使用-LMLPHP
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");
	}
}
10-02 20:27
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