MD5加密实战应用

概念：

MD5加密是为了防止在数据库操作时，DBA（数据库管理员）直接获取用户的密码导致信息的泄露而采用的一种加密的方法。

项目结构：

Main：

package com.jd.test; import java.util.Scanner; import java.util.UUID; import com.jd.tool.MD5Tool; import com.jd.tool.db.DBLink; public class Main { private static DBLink db = new DBLink(); public static void main(String[] args) { System.out.println("*********************************"); System.out.println("*\t\t\t\t*"); System.out.println("*\t欢迎使用注册登录系统\t\t*"); System.out.println("*\t\t\t\t*"); System.out.println("*********************************"); while (true) { menu(); } } static void menu() { System.out.println("1、注册");//用户名 密码 确认密码 System.out.println("2、登录");//用户名和密码 System.out.println("3、退出");//System.exit(0); System.out.println("请输入操作，以Enter键结束:"); Scanner scanner = new Scanner(System.in); int option = scanner.nextInt(); switch (option) { case 1:{ System.out.println("请输入用户名："); String userName = scanner.next(); String sql = "select user_name from user_info where user_name =?"; if (db.exist(sql, userName)) { System.out.println("用户名已存在,请重新输入！"); return; } System.out.println("请设置密码："); String password = scanner.next(); System.out.println("请确认密码："); String newpassword = scanner.next(); if(!newpassword.equals(password)) { return; } String id = UUID.randomUUID().toString(); password = MD5Tool.encrypt(password); sql = "insert into user_info(id,user_name,password)values(?,?,?)"; if(db.update(sql, id,userName,password)) { System.out.println("注册成功"); } break; } case 2:{ System.out.println("请输入用户名："); String userName = scanner.next(); System.out.println("请输入密码："); String password = scanner.next(); password = MD5Tool.encrypt(password); String sql = "select user_name from user_info where user_name=? and password=?"; if(db.exist(sql,userName,password)) { System.out.println("登陆成功"); return; } System.out.println("用户名或密码错误！请重新登录"); break; } case 3:{ System.out.println("退出成功"); System.exit(0); } default: System.out.println("I'm Sorry,there is not the "+option+" option,please try again."); } } }

DBLink:

package com.jd.tool.db; import java.sql.Connection; import java.sql.DriverManager; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.sql.SQLException; import java.sql.Statement; import org.apache.log4j.Logger; import com.jd.tool.PropertiesTool; /** * 数据库管理工具类 * * @author DJ */ public class DBLink { private Logger logger = Logger.getLogger(DBLink.class); /** * 获取数据库连接 * * @author DJ */ private Connection getConnection() { try { Class.forName("com.mysql.jdbc.Driver");// 加载驱动 String userName = PropertiesTool.getValue("db.username"); String password = PropertiesTool.getValue("db.password"); String url = PropertiesTool.getValue("db.url"); return DriverManager.getConnection(url, userName, password);// 获取连接 } catch (Exception e) { logger.debug(e.getMessage(), e); } return null; } /** * 查询数据 * * @author DJ */ public void select(String sql, IRowMapper rowMapper) {// 接口无法创建对象，所以rowMapper参数一定指向IRowMapper接口实现类对象 Connection connection = null; Statement statement = null; ResultSet resultSet = null; try { connection = getConnection();// 获取连接 statement = connection.createStatement(); resultSet = statement.executeQuery(sql);// 执行sql,将查询的数据存到ResultSet类型的变量中 rowMapper.rowMapper(resultSet);// 因为rowMapper参数指向IRowMapper接口实现类对象，所以此处将调用接口实现类中所实现的rowMapper方法 多态 } catch (Exception e) { e.printStackTrace(); } finally { close(resultSet, statement, connection); } } /** * 查询数据 * * @author DJ */ public void select(String sql, IRowMapper rowMapper, Object... params) {// 接口无法创建对象，所以rowMapper参数一定指向IRowMapper接口实现类对象 Connection connection = null; PreparedStatement preparedStatement = null; ResultSet resultSet = null; try { connection = getConnection();// 获取连接 preparedStatement = connection.prepareStatement(sql); for (int i = 0; i < params.length; i++) { preparedStatement.setObject(i + 1, params[i]);// 为？赋值 } resultSet = preparedStatement.executeQuery();// 执行sql,将查询的数据存到ResultSet类型的变量中 rowMapper.rowMapper(resultSet);// 因为rowMapper参数指向IRowMapper接口实现类对象，所以此处将调用接口实现类中所实现的rowMapper方法 多态 } catch (Exception e) { e.printStackTrace(); } finally { close(resultSet, preparedStatement, connection); } } /** * 判断SQL语句是否能查出数据 * * @author DJ */ public boolean exist(String sql) { Connection connection = null; Statement statement = null; ResultSet resultSet = null; try { connection = getConnection(); statement = connection.createStatement(); resultSet = statement.executeQuery("select id,name,mobile,address from first_class"); return resultSet.next(); } catch (Exception e) { e.printStackTrace(); } finally { close(resultSet, statement, connection); } return false; } /** * 判断SQL语句是否能查出数据 * * @author DJ */ public boolean exist(String sql, Object... params) { Connection connection = null; PreparedStatement preparedStatement = null; ResultSet resultSet = null; try { connection = getConnection(); preparedStatement = connection.prepareStatement(sql); for (int i = 0; i < params.length; i++) { preparedStatement.setObject(i + 1, params[i]);// 为？赋值 } resultSet = preparedStatement.executeQuery();//执行sql,将查询的数据存到ResultSet类型的变量中 return resultSet.next(); } catch (Exception e) { e.printStackTrace(); } finally { close(resultSet, preparedStatement, connection); } return false; } /** * 修改（insert、update和delete）数据 * * @author DJ */ public boolean update(String sql) { Connection connection = null; Statement statement = null; try { connection = getConnection(); statement = connection.createStatement(); int result = statement.executeUpdate(sql); // statement.close();//如果上面代码出现异常，则该行代码及其下面代码无法执行，比如sql语句语法错误，则statement和connection无法释放 // connection.close(); return result > 0;// 处理结果 } catch (Exception e) { e.printStackTrace(); } finally {// 即便有异常也会执行代码 close(statement, connection); } return false; } /** * 修改（insert、update和delete）数据 * * @author DJ */ public boolean update(String sql, Object... params) { Connection connection = null; PreparedStatement preparedStatement = null; try { connection = getConnection(); preparedStatement = connection.prepareStatement(sql);// 不完整的sql，含有？占位符的sql for (int i = 0; i < params.length; i++) { preparedStatement.setObject(i + 1, params[i]);// 为？赋值 } return preparedStatement.executeUpdate() > 0; } catch (Exception e) { e.printStackTrace(); } finally { close(preparedStatement, connection); } return false; } /** * 释放资源 * * @author DJ */ private void close(Statement statement, Connection connection) { try { if (statement != null) {// 可能由于异常导致statement没有赋值，比如url出错 statement.close(); } } catch (SQLException e1) { e1.printStackTrace(); } try { if (connection != null) { connection.close(); } } catch (SQLException e) { e.printStackTrace(); } } /** * 释放资源 * * @author DJ */ private void close(ResultSet resultSet, Statement statement, Connection connection) { try { if (resultSet != null) { resultSet.close(); } } catch (SQLException e) { e.printStackTrace(); } close(statement, connection); } }

IRowMapper:

package com.jd.tool.db; import java.sql.ResultSet; public interface IRowMapper { void rowMapper(ResultSet rs); }

MD5Tool：

package com.jd.tool; import java.math.BigInteger; import java.security.MessageDigest; public class MD5Tool { public static String encrypt(String password) { byte[] bytes = null; try { MessageDigest messageDigest = MessageDigest.getInstance("MD5"); messageDigest.update(password.getBytes());//加密 bytes = messageDigest.digest();//获得加密结果 } catch (Exception e) { e.printStackTrace(); } String result = new BigInteger(1, bytes).toString(16);// 将加密后的数据转换为16进制数字 // 生成数字未满32位，则前面补0 for (int i = 0; i < 32 - result.length(); i++) { result = "0" + result; } return result; } }

PropertiesTool:

package com.jd.tool; import java.io.IOException; import java.io.InputStream; import java.util.Properties; public class PropertiesTool { private static Properties properties = new Properties(); static { InputStream inputStream = PropertiesTool.class.getClassLoader().getResourceAsStream("db.properties");// 将db.properties变为javaIO流对象 try { properties.load(inputStream); } catch (IOException e) { e.printStackTrace(); } } public static void main(String[] ages) { String userName = properties.getProperty("db.username"); System.out.print(userName); } public static String getValue(String key) { return properties.getProperty(key); } }

db.properties:

db.username=root db.password=root db.url=jdbc:mysql://127.0.0.1:3306/test

log4j.properties:

# DEBUG\u8BBE\u7F6E\u8F93\u51FA\u65E5\u5FD7\u7EA7\u522B\uFF0C\u7531\u4E8E\u4E3ADEBUG\uFF0C\u6240\u4EE5ERROR\u3001WARN\u548CINFO \u7EA7\u522B\u65E5\u5FD7\u4FE1\u606F\u4E5F\u4F1A\u663E\u793A\u51FA\u6765 log4j.rootLogger=DEBUG,RollingFile #\u5C06\u65E5\u5FD7\u4FE1\u606F\u8F93\u51FA\u5230\u63A7\u5236\u53F0 log4j.appender.Console=org.apache.log4j.ConsoleAppender log4j.appender.Console.layout=org.apache.log4j.PatternLayout log4j.appender.Console.layout.ConversionPattern= [%-5p]-[%d{yyyy-MM-dd HH:mm:ss}] -%l -%m%n #\u5C06\u65E5\u5FD7\u4FE1\u606F\u8F93\u51FA\u5230\u64CD\u4F5C\u7CFB\u7EDFD\u76D8\u6839\u76EE\u5F55\u4E0B\u7684log.log\u6587\u4EF6\u4E2D log4j.appender.RollingFile=org.apache.log4j.DailyRollingFileAppender log4j.appender.RollingFile.File=D://log.log log4j.appender.RollingFile.layout=org.apache.log4j.PatternLayout log4j.appender.RollingFile.layout.ConversionPattern=%d [%t] %-5p %-40.40c %X{traceId}-%m%n