Java 实现用户注册登陆

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;

二.项目结构图：

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" /> <!-- 用隐藏域来判断登陆还是注册 --><input type="submit" value="登陆"/><br/><br /></form><button onclick="window.location='register.jsp'">注册</button>${sessionScope.errorMsg} <!-- EL语法--获取session的errorMsg并显示 --></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 drivertry {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 returnif (time < m_lastClearClosedConnection) {time = m_lastClearClosedConnection;return;}// no need check very oftenif (time - m_lastClearClosedConnection < CHECK_CLOSED_CONNECTION_TIME) {return;}m_lastClearClosedConnection = time;// begin checkIterator 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 bigint 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

五.完整源代码包含jar包地址：

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