学生注册系统+MD5加密实战
首先,在eclipse中的代码结构是：
按图顺序代码分别为：
Main.java:
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 {
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();
System.out.println("请输入密码");
String password = scanner.next();
System.out.println("请输入确认密码");
String rePassword = scanner.next();
String sql = "select id from user_info1 where user_name=?";
if (new DBLink().exist(sql,userName)) {
System.out.println("用户名已存在，请返回操作！");
return;
}
if(!rePassword.equals(password)) {
System.out.println("两次密码不一致！");
return;
}
password=MD5Tool.encrypt(password);
String id = UUID.randomUUID().toString();
sql="insert into user_info1(id,user_name,password) value ('"+id+"',?,?)";
if(new DBLink().update(sql, userName,password)) {
System.out.println("注册成功！");
return;
}
System.out.println("注册失败！");
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 id from user_info1 where user_name =? and password =?";
if (new DBLink().exist(sql,userName,password )){
System.out.println("登录成功！");
return;
}
System.out.println("用户名或密码错误，登录失败，请返回操作！");
break;
}
case 3:{
System.out.println("已退出系统");
System.exit(0);
}
default:
System.out.println("I'm Sorry,there is not the "+option+" option,please try again.");
}
}
}
DBLink.java:
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
*
*
*/
public class DBLink {
private Logger logger = Logger.getLogger(DBLink.class);
/**
* 获取数据库连接
*
*
*/
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;
}
/**
* 判断SQL语句是否能查出数据
*
*
*/
public boolean exist(String sql) {
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
return resultSet.next();
} catch (Exception e) {
logger.debug(e.getMessage(), e);
}finally {
close(resultSet,statement,connection);
}
return false;
}
/**
* 判断SQL语句是否能查出数据
*
*
*/
public boolean exist(String sql, Object ...params) {
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]);
}
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) {
logger.debug(e.getMessage(), e);
}finally {
close(resultSet,preparedStatement,connection);
}
return false;
}
/**
* 查询数据
*
*
*/
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) {
logger.debug(e.getMessage(), e);
}finally {//释放资源
close(resultSet,statement,connection);
}
}
/**
* 查询数据
*
*
*/
public void select(String sql,IRowMapper rowMapper,Object ...params) {
Connection connection = null;
PreparedStatement preparedStatement =null;
ResultSet resultSet=null;
try {
connection = getConnection();//获取连接
preparedStatement= connection.prepareStatement(sql);//含有？号占位符的sql
for (int i = 0; i < params.length; i++) {
preparedStatement.setObject(i+1, params[i]);//为？号赋值
}
resultSet= preparedStatement.executeQuery();//执行sql
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) {
logger.debug(e.getMessage(), e);
}finally {//释放资源
close(resultSet,preparedStatement,connection);
}
}
/**
* 修改（insert、update和delete）数据
*
*
*/
public boolean update(String sql) {
Connection connection = null;
Statement statement = null;
try {
connection = getConnection();//获取数据库连接对象，一个对象表示一次数据库连接
statement = connection.createStatement();//获取Statement对象
int result = statement.executeUpdate(sql);//执行sql语句，返回受影响的行数，仅限于数据insert、update和delete
return result>0;//处理结果
} catch (Exception e) {
logger.debug(e.getMessage(), e);
}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
*
*
*/
public boolean update(String sql,Object ...params) {
Connection connection= null;
PreparedStatement preparedStatement= null;
try {
connection= getConnection();
preparedStatement= connection.prepareStatement(sql);//含有？号占位符的sql
for (int i = 0; i < params.length; i++) {
preparedStatement.setObject(i+1, params[i]);//为？号赋值
}
return preparedStatement.executeUpdate()>0;
} catch (Exception e) {
logger.debug(e.getMessage(), e);
}finally {
close(preparedStatement,connection);
}
return false;
}
/**
* 释放资源
*
*
*/
private void close(Statement statement,Connection connection) {
try {
if(statement!=null) {//有可能由于异常导致statement没有赋值，比如url出错
statement.close();
}
} catch (SQLException e) {
logger.debug(e.getMessage(), e);
}
try {
if(connection!=null) {
connection.close();
}
} catch (SQLException e) {
logger.debug(e.getMessage(), e);
}
}
/**
* 释放资源
*
*
*/
private void close(ResultSet resultSet,Statement statement,Connection connection) {//重载
try {
if(resultSet!=null) {
resultSet.close();
}
} catch (SQLException e) {
logger.debug(e.getMessage(), e);
}
close(statement,connection);
}
}
IRowMapper.java:
package com.jd.tool.db;
import java.sql.ResultSet;
public interface IRowMapper {
void rowMapper(ResultSet rs);
}
MD5Tool.java:
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.java:
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 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
db.driver=com.mysql.jdbc.Driverlog4j.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,Console,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
MYSQL:
