package util;

import java.sql.Connection;
import java.sql.DriverManager;
public class DBHelper {
 private static final String driver = "com.mysql.jdbc.Driver"; //数据库驱动
 //连接数据库的URL地址
 private static final String url="jdbc:mysql://localhost:3306/shopping?useUnicode=true&characterEncoding=UTF-8";
 private static final String username="root";//数据库的用户名
 private static final String password="";//数据库的密码
   
 private static Connection conn=null;
 
 //静态代码块负责加载驱动
 static
 {
  try
  {
   Class.forName(driver);
  }
  catch(Exception ex)
  {
   ex.printStackTrace();
  }
 }
 
 //单例模式返回数据库连接对象
 public static Connection getConnection() throws Exception
 {
  if(conn==null)
  {
   conn = DriverManager.getConnection(url, username, password);
   return conn;
  }
  return conn;
 }
 
 public static void main(String[] args) {
  
  try
  {
     Connection conn = DBHelper.getConnection();
     if(conn!=null)
     {
      System.out.println("数据库连接正常！");
     }
     else
     {
      System.out.println("数据库连接异常！");
     }
  }
  catch(Exception ex)
  {
   ex.printStackTrace();
  }
  
 }
}

Sat Mar 24 02:30:06 CST 2018 WARN: Establishing SSL connection without server's identity verification is not recommended. According to MySQL 5.5.45+, 5.6.26+ and 5.7.6+ requirements SSL connection must be established by default if explicit option isn't set. For compliance with existing applications not using SSL the verifyServerCertificate property is set to 'false'. You need either to explicitly disable SSL by setting useSSL=false, or set useSSL=true and provide truststore for server certificate verification.
java.sql.SQLException: Access denied for user 'root'@'localhost' (using password: NO)
 at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:965)
 at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3976)
 at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3912)
 at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:871)
 at com.mysql.jdbc.MysqlIO.proceedHandshakeWithPluggableAuthentication(MysqlIO.java:1714)
 at com.mysql.jdbc.MysqlIO.doHandshake(MysqlIO.java:1224)
 at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2190)
 at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2221)
 at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2016)
 at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:776)
 at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:47)
 at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
 at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
 at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
 at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
 at com.mysql.jdbc.Util.handleNewInstance(Util.java:425)
 at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:386)
 at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:330)
 at java.sql.DriverManager.getConnection(DriverManager.java:664)
 at java.sql.DriverManager.getConnection(DriverManager.java:247)
 at util.DBHelper.getConnection(DBHelper.java:32)
 at util.DBHelper.main(DBHelper.java:42)