package util;
 
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
 
public class ConnectionManager {
  public static Connection getConnection() {
    Connection conn = null;
    try {
      Class.forName("com.mysql.jdbc.Driver");
      String url = "jdbc:mysql://localhost:3306/mail";
      String username = "root";
      String password = "root";
      conn = DriverManager.getConnection(url, username, password);
    } catch (ClassNotFoundException e1) {
      e1.printStackTrace();
    } catch (SQLException e) {
      e.printStackTrace();
    }
    return conn;
  }
 
}

package util;
 
import java.io.IOException;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.Properties;
 
public class JdbcUtil {
  private static String dirverName;
  private static String url;
  private static String username;
  private static String password;
//  利用靜態(tài)塊i，在類加載的時(shí)候就被執(zhí)行
  static{
    try {
//      用流讀入properties配置文件
      InputStream inputStream = JdbcUtil.class.getClassLoader()
          .getResourceAsStream("datebase.properties");
      Properties properties = new Properties();
//      從輸入字節(jié)流讀取屬性列表（鍵和元素對(duì)）
      properties.load(inputStream);
//      用此屬性列表中指定的鍵搜索屬性，獲取驅(qū)動(dòng)，url，username，password
      dirverName = properties.getProperty("driverName");
      url = properties.getProperty("url");
      username = properties.getProperty("username");
      password = properties.getProperty("password");
      System.out.println(dirverName);
      System.out.println(url);
      System.out.println(username);
      System.out.println(password);
//      加載驅(qū)動(dòng)
      Class.forName(dirverName);
    } catch (IOException e) {
      e.printStackTrace();
    } catch (ClassNotFoundException e) {
      e.printStackTrace();
    }
 
  }
 
//  獲取數(shù)據(jù)庫(kù)連接
  public static Connection getConnection() {
    Connection conn=null;
    try {
      conn=DriverManager.getConnection(url, username, password);
    } catch (SQLException e) {
      e.printStackTrace();
    }
    return conn;
  }
  
//測(cè)試
  public static void main(String[] args) {
    JdbcUtil.getConnection();
  }
}

com.mysql.jdbc.Driver
jdbc:mysql://localhost:3306/mail
root
root