MySQL 数据库连接 静态语句块

package cn.sjy.org.dbconn;

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

import cn.sjy.org.exception.*;

public class MysqlDBConn {
  private static final String DBDRIVER = "com.mysql.jdbc.Driver";
  private static final String DBURL = "jdbc:mysql://127.0.0.1:3306/book";
  private static final String DBUSER = "root";
  private static final String DBPASSWORD = "root";
  private static MysqlDBConn mysqldbconn = null;
  Connection conn = null;
  static{
   try {
    Class.forName(DBDRIVER);
   } catch (ClassNotFoundException e) {
    e.printStackTrace();
    throw new MyRunTimeException("驱动加载失败", e);
   }
  }
  
  public static MysqlDBConn getMysqlDBConn(){
   if(mysqldbconn == null){mysqldbconn = new MysqlDBConn();}
   return mysqldbconn;
  }
  
  public  Connection getconnection(){
   try {
    conn = DriverManager.getConnection(this.DBURL, this.DBUSER, this.DBPASSWORD);
   } catch (SQLException e) {
    e.printStackTrace();
    throw new MyRunTimeException("连接数据库失败", e);
   }
   return conn;
  }
  
}