maven项目连接MySQL（使用原生的jdbc）

//依赖

<dependency>

<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.45</version>

</dependency>

jdbc.properties  内容：

driver=com.mysql.jdbc.Driver
url=jdbc:mysql://localhost:3306/shiro?useUnicode=true&characterEncoding=utf-8&useSSL=false

username=root

password=123456

package com.cxb.shiro;


import java.io.IOException;
import java.util.Properties;


/**
 * 获取资源文件的util
 * @author 81046
 *
 */
public class PropertiesUtil {
static Properties properties = new Properties();


    public PropertiesUtil() {
    }
    public static boolean loadFile(String fileName){
        try {
            properties.load(PropertiesUtil.class.getClassLoader().getResourceAsStream(fileName));
        } catch (IOException e) {
            e.printStackTrace();
            return false;
        }
        return true;
    }
    public static String getPropertyValue(String key){
        return properties.getProperty(key);
    }

}

package com.cxb.shiro;


import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;




public class JdbcUtils {


//通过上面的工具就可以获取到properties文件中的键值从而可以加载驱动 获取链接 从而 可以增删改查
    private static Connection conn = null;




    public static Connection getConn(){
        PropertiesUtil.loadFile("jdbc.properties");
        String driver = PropertiesUtil.getPropertyValue("driver");
        String url = PropertiesUtil.getPropertyValue("url");
        String username  = PropertiesUtil.getPropertyValue("username");
        String password = PropertiesUtil.getPropertyValue("password");


        try {
            Class.forName(driver);
            conn = DriverManager.getConnection(url,username,password);


        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (SQLException e) {
            e.printStackTrace();
            close();
        }
        return conn;
    }
    
    
    public static void close(){
        try {
            conn.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

}

/**
* 通过用户名到数据库中获取凭证密码
* @param userName
* @return
*/
private static String getPasswordByUserName(String userName) {
//SQL语句  
String sql = "select password from users where username = " +"'" + userName+"'";
    Connection conn = JdbcUtils.getConn();
    Statement stmt=null; 
    ResultSet ret = null;  
    String password=null;
try {
stmt = conn.createStatement();
//执行语句，得到结果集  
ret = stmt.executeQuery(sql);
            while (ret.next()) {  
            //这里只查询的密码
            password = ret.getString(1);  
            }
            ret.close();  
            conn.close();//关闭连接  
} catch (SQLException e1) {
e1.printStackTrace();
}  
return password;
}