package student;
import java.lang.*;
import java.sql.*;
public class JDBCoracle{
   
        
        public static final String driverClassName = "oracle.jdbc.driver.OracleDriver";
        public static final String url = "jdbc:oracle:thin:@localhost:1521:orcl";
        public static final String password = "472312";
        public static final String user= "sys as sysdba";
        public static void main(String[] args) throws Exception{
             Connection conn = null;
             Class.forName(driverClassName);
             conn = DriverManager.getConnection(url, user, password);
            System.out.println(conn);
            conn.close();
            
         
        }
    }
错误异常：
Exception in thread "main" java.sql.SQLException: Io 异常: The Network Adapter could not establish the connection
    at oracle.jdbc.dbaccess.DBError.throwSqlException(DBError.java:189)
    at oracle.jdbc.dbaccess.DBError.throwSqlException(DBError.java:231)
    at oracle.jdbc.dbaccess.DBError.throwSqlException(DBError.java:345)
    at oracle.jdbc.driver.OracleConnection.<init>(OracleConnection.java:428)
    at oracle.jdbc.driver.OracleDriver.getConnectionInstance(OracleDriver.java:515)
    at oracle.jdbc.driver.OracleDriver.connect(OracleDriver.java:345)
    at java.sql.DriverManager.getConnection(Unknown Source)
    at java.sql.DriverManager.getConnection(Unknown Source)
    at student.JDBCoracle.main(JDBCoracle.java:14)