Java 实现用户注册登陆

水深无声 2022-05-13 13:18 243阅读 0赞

一个用户注册登陆的系统，用到了MD5加密处理密码，实现了一个简单的数据库连接池connectionPool,

实现了注册，登陆，登陆之后修改用户信息等功能，非常适合初学者

## 一.准备工作 ##

数据库：MySQL  5.5.62-log MySQL Community Server (GPL)

创建user表，数据库为first\_db;

CREATE TABLE IF NOT EXISTS \`user\`(  
\`user\_id\` INT UNSIGNED AUTO\_INCREMENT,  
 \`username\` VARCHAR(100) NOT NULL,  
 \`password\` VARCHAR(100) NOT NULL,  
 \`phone\` VARCHAR(100) NOT NULL, PRIMARY KEY ( \`user\_id\` )  
)ENGINE=InnoDB DEFAULT CHARSET=utf8;

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3djYzI3ODU3Mjg1_size_16_color_FFFFFF_t_70][]

# #

## 二.项目结构图： ##

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3djYzI3ODU3Mjg1_size_16_color_FFFFFF_t_70 1][]

## 三.部分核心代码 ##

**web.xml： **

实现servlet指向CheckUser类和UpdateUser类，指定login.jsp为首页

<?xml version="1.0" encoding="UTF-8"?>
    <web-app version="3.0" 
    	xmlns="http://java.sun.com/xml/ns/javaee" 
    	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
    	xsi:schemaLocation="http://java.sun.com/xml/ns/javaee 
    	http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd">
      <display-name></display-name>
      <servlet>
        <servlet-name>CheckUser</servlet-name>
        <servlet-class>com.Account.CheckUser</servlet-class>
      </servlet>
      <servlet>
        <servlet-name>UpdateUser</servlet-name>
        <servlet-class>com.Account.UpdateUser</servlet-class>
      </servlet>
    
      <servlet-mapping>
        <servlet-name>CheckUser</servlet-name>
        <url-pattern>/CheckUser</url-pattern>
      </servlet-mapping>
      <servlet-mapping>
        <servlet-name>UpdateUser</servlet-name>
        <url-pattern>/UpdateUser</url-pattern>
      </servlet-mapping> 
      
      <welcome-file-list>
        <welcome-file>login.jsp</welcome-file>
      </welcome-file-list>
    </web-app>

**login.jsp:**

login.jsp是登陆页面，from表单中加了一个<input type="hidden" name="actiontype" value="login" />的隐藏按钮，用于在CheckUser类中判断是登陆还是注册，通过actiontype的值。点击登陆，根据servlet分发到CheckUser类处理请求

<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
    <%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
    
    <!DOCTYPE html>
    <html>
      <head>
        <title>登陆</title>
      </head>
      <body>
            <h2>欢迎登陆</h2>
        	<form action="CheckUser" method="post">
        		账号:<input type="text" name="userName"><br/>
        		密码:<input type="password" name="password"><br/>
        		<input type="hidden" name="actiontype" value="login" /> 
        		<input type="submit" value="登陆"/><br/><br />
        	</form>
      	    <button onclick="window.location='register.jsp'">注册</button>
        	${sessionScope.errorMsg} 
      </body>
    </html>

**CheckUser.java:**

实现处理登陆注册的请求 向数据库请求并返回结果

package com.Account;
    import java.io.IOException;
    
    import java.sql.Connection;
    //import java.sql.DriverManager;
    import java.sql.PreparedStatement;
    import java.sql.ResultSet;
    
    import javax.servlet.ServletException;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    import javax.servlet.http.HttpSession;
    
    @SuppressWarnings("serial")
    public class CheckUser extends HttpServlet {
    	
    	public void doPost(HttpServletRequest request, HttpServletResponse response)
    			throws ServletException, IOException {
    		HttpSession session = request.getSession();
    		String userName = request.getParameter("userName");
    		String password = request.getParameter("password");
    		
    		//md5对密码加密
    		Md5 md5=new Md5();
    		
    		//判断类型是登陆还是注册
    		String Sql="";
    		String action_type = request.getParameter("actiontype");
    		if(action_type.equals("login")){
    			 Sql = "SELECT user_id,username,password,phone FROM user "
    			 		+ "where username='" + userName+ "' AND password='" + md5.MD5(password) + "' ";
    		}else if(action_type.equals("register")){
    			 Sql = "INSERT into user (username,password,phone) values ('"+ userName+"' ,'"+md5.MD5(password) +"',' ')";
    		}
    		
    		Connection connection = null;
    		PreparedStatement preSta = null;
    		ResultSet rs = null;
    		
    		// 建立连接,DriverManager是JDBC的管理层
    		try {
    			//使用连接池的方式连接数据库
    			ConnectionPool.setUrl(ConnectionPool.getUrl());
    			ConnectionPool.setUser(ConnectionPool.getUser());//DBTools.getDatabaseUserName()
    			ConnectionPool.setPassword(ConnectionPool.getPassword());
    
    			connection = ConnectionPool.getConnection();
    			preSta = connection.prepareStatement(Sql);
    			
    			UserInfo info = null;
    		
    			if(action_type.equals("login")) {
    				rs = preSta.executeQuery();
    				while(rs.next()){
    					info = new UserInfo();
    					info.setuser_id(rs.getInt("user_id"));
    					info.setUserName(rs.getString("username"));
    					info.setPassword(rs.getString("password"));
    					info.setPhone(rs.getString("phone"));
    				}
    				if(info != null){
    					session.setAttribute("password", password);
    					session.setAttribute("info", info);
    					String login_suc = "success.jsp";
    					response.sendRedirect(login_suc);
    				}
    				else{
    					String login_fail = "login.jsp";
    					session.setAttribute("errorMsg", "用户名或密码错误，登陆失败！");
    					response.sendRedirect(login_fail); 
    				}
    			}
    			else if(action_type.equals("register")){
     			   int count= preSta.executeUpdate();
     			   if(count>0){
    					session.setAttribute("registerMsg", "注册成功！");
    				}
    				else{
    					session.setAttribute("registerMsg", "注册失败，请重试！");
    				}
     				response.sendRedirect("register.jsp");
    			}
    		} catch (Exception e) {
    			e.printStackTrace();
    		}
    		// 关闭连接
    		finally {
    			if(connection!=null){
    				try{
    					connection.close();
    				}catch(Exception e){}
    			}
    			if(preSta!=null){
    				try{
    					preSta.close();
    				}catch(Exception e){}
    			}
    			if(rs!=null){
    				try{
    					rs.close();
    				}catch(Exception e){}
    			}
    		}
    	}
    }

**MD5.Java:**

MD5加密类，给password字段加密

package com.Account;
    
    import java.security.MessageDigest;
    
    public class Md5 {
    	public final String MD5(String s) {//MD5加密方法
            char hexDigits[]={'0','1','2','3','4','5','6','7','8','9','A','B','C','D','E','F'};       
            try {
                byte[] btInput = s.getBytes();
                // 获得MD5摘要算法的 MessageDigest 对象
                MessageDigest mdInst = MessageDigest.getInstance("MD5");
                // 使用指定的字节更新摘要
                mdInst.update(btInput);
                // 获得密文
                byte[] md = mdInst.digest();
                // 把密文转换成十六进制的字符串形式
                int j = md.length;
                char str[] = new char[j * 2];
                int k = 0;
                for (int i = 0; i < j; i++) {
                    byte byte0 = md[i];
                    str[k++] = hexDigits[byte0 >>> 4 & 0xf]; //>>>不带符号 右移 四位(位移处补0)
                    str[k++] = hexDigits[byte0 & 0xf];
                }
                return new String(str);
            } catch (Exception e) {
                e.printStackTrace();
                return null;
            }
    	}
    }

**ConnectionPool.java:**

手动实现一个简单的数据库连接池，提升性能

package com.Account;
    
    import java.sql.*;
    import java.lang.reflect.*;
    import java.util.*;
    import java.io.*;
    
    public class ConnectionPool {
    	private static LinkedList m_notUsedConnection = new LinkedList();
    	private static HashSet m_usedUsedConnection = new HashSet();
    	private static String m_url = "jdbc:mysql://localhost:3306/first_db";
    	private static String m_user = "root";
    	private static String m_password = "123456";
    	static final boolean DEBUG = true;
    	static private long m_lastClearClosedConnection = System.currentTimeMillis();
    	public static long CHECK_CLOSED_CONNECTION_TIME = 4 * 60 * 60 * 1000; // 4小时
    	
    	private void ConnectionPool() {
    	}
    	
    	static {
    		initDriver();
    	}
    
    	private static void initDriver() {
    		Driver driver = null;
    		// load mysql driver
    		try {
    			driver = (Driver) Class.forName("com.mysql.jdbc.Driver").newInstance();
    			installDriver(driver);
    		} catch (Exception e) {
    		}
    	}
    
    	public static void installDriver(Driver driver) {
    		try 
    		{
    			DriverManager.registerDriver(driver);
    		} 
    		catch (Exception e)
    		{
    			e.printStackTrace();
    		}
    	}
    
    	public static synchronized Connection getConnection() {
    		clearClosedConnection();
    		while (m_notUsedConnection.size() > 0) {
    			try {
    				ConnectionWrapper wrapper = (ConnectionWrapper) m_notUsedConnection
    						.removeFirst();
    				if (wrapper.connection.isClosed()) {
    					continue;
    				}
    				m_usedUsedConnection.add(wrapper);
    				if (DEBUG) {
    					wrapper.debugInfo = new Throwable(
    							"Connection initial statement");
    				}
    				return wrapper.connection;
    			} catch (Exception e) {
    			}
    		}
    		int newCount = getIncreasingConnectionCount();
    		LinkedList list = new LinkedList();
    		ConnectionWrapper wrapper = null;
    		for (int i = 0; i < newCount; i++) {
    			wrapper = getNewConnection();
    			if (wrapper != null) {
    				list.add(wrapper);
    			}
    		}
    		if (list.size() == 0) {
    			return null;
    		}
    		wrapper = (ConnectionWrapper) list.removeFirst();
    		m_usedUsedConnection.add(wrapper);
    
    		m_notUsedConnection.addAll(list);
    		list.clear();
    
    		return wrapper.connection;
    	}
    
    	private static ConnectionWrapper getNewConnection() {
    		try {
    			Connection con = DriverManager.getConnection(m_url, m_user,
    					m_password);
    			ConnectionWrapper wrapper = new ConnectionWrapper(con);
    			return wrapper;
    		} catch (Exception e) {
    			e.printStackTrace();
    		}
    		return null;
    	}
    
    	static synchronized void pushConnectionBackToPool(ConnectionWrapper con) {
    		boolean exist = m_usedUsedConnection.remove(con);
    		if (exist) {
    			m_notUsedConnection.addLast(con);
    		}
    	}
    
    	public static int close() {
    		int count = 0;
    
    		Iterator iterator = m_notUsedConnection.iterator();
    		while (iterator.hasNext()) {
    			try {
    				((ConnectionWrapper) iterator.next()).close();
    				count++;
    			} catch (Exception e) {
    			}
    		}
    		m_notUsedConnection.clear();
    
    		iterator = m_usedUsedConnection.iterator();
    		while (iterator.hasNext()) {
    			try {
    				ConnectionWrapper wrapper = (ConnectionWrapper) iterator.next();
    				wrapper.close();
    				if (DEBUG) {
    					wrapper.debugInfo.printStackTrace();
    				}
    				count++;
    			} catch (Exception e) {
    			}
    		}
    		m_usedUsedConnection.clear();
    
    		return count;
    	}
    
    	private static void clearClosedConnection() {
    		long time = System.currentTimeMillis();
    		// sometimes user change system time,just return
    		if (time < m_lastClearClosedConnection) {
    			time = m_lastClearClosedConnection;
    			return;
    		}
    		// no need check very often
    		if (time - m_lastClearClosedConnection < CHECK_CLOSED_CONNECTION_TIME) {
    			return;
    		}
    		m_lastClearClosedConnection = time;
    
    		// begin check
    		Iterator iterator = m_notUsedConnection.iterator();
    		while (iterator.hasNext()) {
    			ConnectionWrapper wrapper = (ConnectionWrapper) iterator.next();
    			try {
    				if (wrapper.connection.isClosed()) {
    					iterator.remove();
    				}
    			} catch (Exception e) {
    				iterator.remove();
    				if (DEBUG) {
    					System.out
    							.println("connection is closed, this connection initial StackTrace");
    					wrapper.debugInfo.printStackTrace();
    				}
    			}
    		}
    
    		// make connection pool size smaller if too big
    		int decrease = getDecreasingConnectionCount();
    		if (m_notUsedConnection.size() < decrease) {
    			return;
    		}
    
    		while (decrease-- > 0) {
    			ConnectionWrapper wrapper = (ConnectionWrapper) m_notUsedConnection
    					.removeFirst();
    			try {
    				wrapper.connection.close();
    			} catch (Exception e) {
    			}
    		}
    	}
    
    	/**
    	 * get increasing connection count, not just add 1 connection
    	 * 
    	 * @return count
    	 */
    	public static int getIncreasingConnectionCount() {
    		int count = 1;
    		int current = getConnectionCount();
    		count = current / 4;
    		if (count < 1) {
    			count = 1;
    		}
    		return count;
    	}
    
    	/**
    	 * get decreasing connection count, not just remove 1 connection
    	 * 
    	 * @return count
    	 */
    	public static int getDecreasingConnectionCount() {
    		int count = 0;
    		int current = getConnectionCount();
    		if (current < 10) {
    			return 0;
    		}
    		return current / 3;
    	}
    
    	public synchronized static void printDebugMsg() {
    		printDebugMsg(System.out);
    	}
    
    	public synchronized static void printDebugMsg(PrintStream out) {
    		if (DEBUG == false) {
    			return;
    		}
    		StringBuffer msg = new StringBuffer();
    		msg.append("debug message in " + ConnectionPool.class.getName());
    		msg.append("\r\n");
    		msg.append("total count is connection pool: " + getConnectionCount());
    		msg.append("\r\n");
    		msg.append("not used connection count: " + getNotUsedConnectionCount());
    		msg.append("\r\n");
    		msg.append("used connection, count: " + getUsedConnectionCount());
    		out.println(msg);
    		Iterator iterator = m_usedUsedConnection.iterator();
    		while (iterator.hasNext()) {
    			ConnectionWrapper wrapper = (ConnectionWrapper) iterator.next();
    			wrapper.debugInfo.printStackTrace(out);
    		}
    		out.println();
    	}
    
    	public static synchronized int getNotUsedConnectionCount() {
    		return m_notUsedConnection.size();
    	}
    
    	public static synchronized int getUsedConnectionCount() {
    		return m_usedUsedConnection.size();
    	}
    
    	public static synchronized int getConnectionCount() {
    		return m_notUsedConnection.size() + m_usedUsedConnection.size();
    	}
    
    	public static String getUrl() {
    		return m_url;
    	}
    
    	public static void setUrl(String url) {
    		if (url == null) {
    			return;
    		}
    		m_url = url.trim();
    	}
    
    	public static String getUser() {
    		return m_user;
    	}
    
    	public static void setUser(String user) {
    		if (user == null) {
    			return;
    		}
    		m_user = user.trim();
    	}
    
    	public static String getPassword() {
    		return m_password;
    	}
    
    	public static void setPassword(String password) {
    		if (password == null) {
    			return;
    		}
    		m_password = password.trim();
    	}
    
    }
    
    class ConnectionWrapper implements InvocationHandler {
    	private final static String CLOSE_METHOD_NAME = "close";
    	public Connection connection = null;
    	private Connection m_originConnection = null;
    	public long lastAccessTime = System.currentTimeMillis();
    	Throwable debugInfo = new Throwable("Connection initial statement");
    
    	ConnectionWrapper(Connection con) {
    		this.connection = (Connection) Proxy.newProxyInstance(
    		con.getClass().getClassLoader(),
    		new Class[]{Connection.class}, this);
    		m_originConnection = con;
    	}
    
    	void close() throws SQLException {
    		m_originConnection.close();
    	}
    
    	public Object invoke(Object proxy, Method m, Object[] args)
    			throws Throwable {
    		Object obj = null;
    		if (CLOSE_METHOD_NAME.equals(m.getName())) {
    			ConnectionPool.pushConnectionBackToPool(this);
    		} else {
    			obj = m.invoke(m_originConnection, args);
    		}
    		lastAccessTime = System.currentTimeMillis();
    		return obj;
    	}
    
    }

## 四.完成效果 ##

首先user表是空的，然后在首页注册用户，然后查看数据库信息已经注册成功，再进行登陆，登陆成功后跳转到个人中心页面，修改密码手机等信息，完成后再次查看数据库

![20181111235626689.gif][]

## 五.完整源代码包含jar包地址： ##

[https://download.csdn.net/download/wcc27857285/10778616][https_download.csdn.net_download_wcc27857285_10778616]

PS后续：

我看了下大家都想要源代码和jar包地址，按原先的下载地址需要16个csdn积分，其实一开始我是随便设置的16积分、

后来我想改成免费的，但是无奈CSDN一波骚操作，我一通操作，还是改不了，所以我特地把代码放在了云盘上，供大家免费下载

链接：https://pan.baidu.com/s/1ccxDBkS\_UaGX6Kw6uyM55A   
提取码：p4ls

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3djYzI3ODU3Mjg1_size_16_color_FFFFFF_t_70]: /images/20220504/d61df950115e4d8a96860965e02aa7d1.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3djYzI3ODU3Mjg1_size_16_color_FFFFFF_t_70 1]: /images/20220504/b0b707262a5348ce906c12d6331ac5b3.png
[20181111235626689.gif]: /images/20220504/b540615a6317489b8edf9f2aa1e7ab7e.png
[https_download.csdn.net_download_wcc27857285_10778616]: https://download.csdn.net/download/wcc27857285/10778616