标签：业务逻辑 vax extends path 注销 override stream http project
现在我们写代码，基本都是各种框架用的飞起，提起Servlet，感觉是很久远的事情了...
但无论怎样，Servlet都是基础，各种框架都是在Servlet的基础上封装的。这篇，我们来复习下Servlet。
闲话少说，贴代码，自己写的一个登录注册的例子，代码可以直接拿去用，但没有cs之类的。
环境：JDK7+Tomcat8+MySQL8
项目架构：
Entity：
package com.rain.entity;
/**
* @author 047493
* @version 2019年5月21日
* entity：实体模型层
* User：实体类
*/
public class User {
private int id;
private String userName;
private String password;
private String email;
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;
}
public String getEmail(){
return email;
}
public void setEmain(String email){
this.email = email;
}
@Override
public String toString(){
return "User [id=" +id+ ",userName=" +userName+ ",password=" +password+ ",email=" +email+"]";
}
}
Controller：
package com.rain.controller;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import com.rain.entity.User;
import com.rain.service.UserService;
import com.rain.service.impl.UserServiceImpl;
/*@WebServlet("/UserServlet")*/
public class UserServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
UserService userService = new UserServiceImpl();
public UserServlet() {
super();
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doPost(request,response);
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
String method = request.getParameter("method");
//如果传入的参数是login
if("login".equals(method)){
login(request,response);
}else if("regist".equals(method)){
regist(request,response);
}else if("toLogin".equals(method)){
toLogin(request,response);
}else if("logout".equals(method)){
logout(request,response);
}else if("toRegist".equals(method)){
toRegist(request,response);
}else {
request.setAttribute("msg", "该功能正在开发。。。");
request.getRequestDispatcher("/message.jsp").forward(request, response);
}
}
//注册
private void regist(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
User user = new User();
//获取前台jsp页面参数
String userName = request.getParameter("userName");
String password = request.getParameter("password");
String email = request.getParameter("email");
//将接收到的参数封装到user对象中去
user.setUserName(userName);
user.setPassword(password);
user.setEmain(email);
//判断用户名密码是否为空
//if(StringUtils.isNotBlank(user.getUserName()) && StringUtils.isNotBlank(user.getPassword())){
if((userName != null && userName.length() != 0)&&(password != null && password.length() != 0)){
int rows = userService.userRegister(user);
if(rows > 0){
response.setHeader("refresh", "1;url=UserServlet?method=toLogin");
} else {
response.setHeader("msg", "注册失败！");
request.getRequestDispatcher("/message").forward(request, response);
}
} else {
request.setAttribute("msg", "用户名密码不允许为空！");
request.getRequestDispatcher("/message").forward(request, response);
}
}
//登录
public void login(HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException{
//获取前台jsp表单传递的参数
String userName = request.getParameter("userName");
String password = request.getParameter("password");
//根据参数进行判断
//1、用户名密码均不为空
//if(StringUtils.isNotBlank(userName) && StringUtils.isNotBlank(password)){
if((userName != null && userName.length() != 0)&&(password != null && password.length() != 0)){
//2、传递到service层登录方法
User user = userService.userLogin(userName, password);
//3、判断用户信息是否查询得到
if(user != null){
//查询到，存入session
request.getSession().setAttribute("USER_SESSION", user);
//登录成功，跳转至主页
request.getRequestDispatcher("/WEB-INF/jsp/main.jsp").forward(request, response);
}else{
//未查询到或者用户名密码不匹配，会将失败的信息存储到msg中
request.setAttribute("msg", "用户名或密码错误！");
//登录失败，转向错误信息提示页，根据存入的msg取出相对应的内容
request.getRequestDispatcher("/message.jsp").forward(request, response);
}
}else{
//如果用户名或密码为空
request.setAttribute("msg", "用户名密码不允许为空！");
request.getRequestDispatcher("/WEB-INF/jsp/login.jsp").forward(request, response);
}
}
//转向注册
private void toRegist(HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException {
request.getRequestDispatcher("/WEB-INF/jsp/regist.jsp").forward(request, response);
}
//注销
private void logout(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
request.getSession().invalidate();
request.getRequestDispatcher("/WEB-INF/jsp/login.jsp").forward(request, response);
}
//转向到登录页面
private void toLogin(HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException {
request.getRequestDispatcher("/WEB-INF/jsp/login.jsp").forward(request, response);
}
}
Service：接口＋实现类
package com.rain.service;
import com.rain.entity.User;
/**
* @author 047493
* @version 2019年5月22日
* 业务逻辑层接口
*/
public interface UserService {
//用户登录
User userLogin(String userName,String password);
//用户注册
int userRegister(User user);
}
package com.rain.service.impl;
import com.rain.dao.impl.UserDaoImpl;
import com.rain.entity.User;
import com.rain.service.UserService;
/**
* @author 047493
* @version 2019年5月22日
* 业务逻辑层实现类
*/
public class UserServiceImpl implements UserService{
private UserDaoImpl userDao = new UserDaoImpl();
@Override
public User userLogin(String userName, String password) {
User user = userDao.login(userName, password);
return user;
}
@Override
public int userRegister(User user) {
return userDao.regist(user);
}
}
DAO：接口＋实现类
package com.rain.dao;
import com.rain.entity.User;
/**
* @author 047493
* @version 2019年5月21日
* Dao：数据持久层接口
*/
public interface UserDao {
//登录
User login(String userName,String password);
//注册
int regist(User user);
}
package com.rain.dao.impl;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import com.rain.dao.UserDao;
import com.rain.entity.User;
import com.rain.util.DBUtil;
/**
* @author 047493
* @version 2019年5月21日
* Impl：数据持久层实现
*/
public class UserDaoImpl implements UserDao{
public static Connection conn;
public static PreparedStatement ps;
public static ResultSet rs;
@Override
public User login(String userName, String password) {
String sql = "select * from t_user where userName=? and password=?";
conn = DBUtil.getConnect();
User user = null;
try {
ps = conn.prepareStatement(sql);
ps.setString(1, userName);
ps.setString(2, password);
rs = ps.executeQuery();
while(rs.next()){
user = new User();
user.setId(rs.getInt("id"));
user.setUserName(rs.getString("userName"));
user.setPassword(rs.getString("password"));
user.setEmain(rs.getString("email"));
}
rs.close();
ps.close();
} catch (SQLException e) {
e.printStackTrace();
} finally {
try {
conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
return user;
}
@Override
public int regist(User user) {
String sql="insert into t_user(userName,password,email) values(?,?,?)";
conn = DBUtil.getConnect();
int i = 0;
try {
ps = conn.prepareStatement(sql);
ps.setString(1, user.getUserName());
ps.setString(2, user.getPassword());
ps.setString(3, user.getEmail());
ps.executeUpdate();
i = 1;
} catch (SQLException e) {
e.printStackTrace();
} finally {
try {
conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
return i;
}
}
Util：数据库连接类
package com.rain.util;
import java.io.IOException;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.Properties;
/**
* @author 047493
* @version 2019年5月21日
* 数据库连接工具类
*/
public class DBUtil {
public static Connection conn;
public static PreparedStatement ps;
public static ResultSet rs;
static{
try {
Class.forName("com.mysql.cj.jdbc.Driver");
System.out.println("加载数据库驱动成功！");
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
}
public static Connection getConnect(){
Properties p = new Properties();
ClassLoader classLoader = Thread.currentThread().getContextClassLoader();
InputStream in = classLoader.getResourceAsStream("db.properties");
String username = null;
String password = null;
String url = null;
try {
p.load(in);
username = p.getProperty("username");
password = p.getProperty("password");
url = p.getProperty("url");
} catch (IOException e) {
e.printStackTrace();
}
if(conn == null){
try {
conn = DriverManager.getConnection(url,username,password);
System.out.println("数据库连接成功！");
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
return conn;
}
public static void CloseConnection(){
try {
if(rs != null){
rs.close();
}
if(ps != null){
ps.close();
}
if(conn != null){
conn.close();
}
}catch (SQLException e) {
e.printStackTrace();
}
}
}
db.properties：
username=root
password=123456
url=jdbc:mysql://127.0.0.1:3306/login?serverTimezone=GMT
web.xml：
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd" id="WebApp_ID" version="3.1">
<display-name>ServletProject</display-name>
<welcome-file-list>
<welcome-file>index.html</welcome-file>
<welcome-file>index.htm</welcome-file>
<welcome-file>index.jsp</welcome-file>
<welcome-file>default.html</welcome-file>
<welcome-file>default.htm</welcome-file>
<welcome-file>default.jsp</welcome-file>
</welcome-file-list>
<servlet>
<servlet-name>UserServlet</servlet-name>
<servlet-class>com.rain.controller.UserServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>UserServlet</servlet-name>
<url-pattern>/UserServlet</url-pattern>
</servlet-mapping>
</web-app>
index.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>首页</title>
</head>
<body>
<jsp:forward page="WEB-INF/jsp/regist.jsp"></jsp:forward>
</body>
</html>
message.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>错误信息提示页</title>
</head>
<body>
${msg}
</body>
</html>
login.jsp：
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>登录页面</title>
</head>
<body>
<div class="page">
<a id="toRegist" href="${pageContext.request.contextPath}/UserServlet?method=toRegist">没有账号，去注册？</a>
<div class="login_form">
<form id="Login" name="Login" action="${pageContext.request.contextPath}/UserServlet?method=login" method="post">
<table>
<tr align="center">
<td>请输入用户名：<input type="text" name="userName" size="20"/></td>
</tr>
<tr align="center">
<td>请输入密码：<input type="password" name="password" size="20"/></td>
</tr>
<tr>
<td><input type="submit" value="登录"/></td>
</tr>
<tr>
<td><input type="reset" value="重置"/></td>
</tr>
</table>
</form>
</div>
</div>
</body>
</html>
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>登录成功页面</title>
</head>
<body>
<center>
<h3>
${sessionScope.USER_SESSION.userName},登录成功
</h3>
<hr/>
<h4>
<a href="${pageContext.request.contextPath}/UserServlet?method=logout">退出系统</a>
</h4>
</center>
</body>
</html>
regist.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>注册页面</title>
</head>
<body>
<form action="${pageContext.request.contextPath}/UserServlet?method=regist" method="post">
<header>请填写表单</header>
<fieldset>
<a id="toLogin" href="${pageContext.request.contextPath}/UserServlet?method=toLogin">已有账号，直接登录</a>
<br/>
<br/>
<section>
<label>
<input type="text" name="userName">
<b>请输入用户名</b>
</label>
</section>
<section>
<label>
<input type="password" name="password">
<b>请输入密码</b>
</label>
</section>
<section>
<label>
<input type="text" name="email">
<b>请输入邮箱</b>
</label>
</section>
</fieldset>
<footer>
<button type="submit">提交注册</button>
</footer>
</form>
</body>
</html>
OK，访问路径：http://localhost:8080/项目名称/index.jsp
先这样~下次补一下关于Servlet的知识点~
标签：业务逻辑 vax extends path 注销 override stream http project
原文地址：https://www.cnblogs.com/Rain1203/p/10919557.html
