java连接oracle数据库出现异常，请教各位高人

[b5575233b3]

连接数据库代码：
public class ConnectionDB {
public static Connection getConn(){
Connection conn=null;
try {
Class.forName("oracle.jdbc.driver.OracleDriver");
conn=DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:orcl","system","admin");
System.out.println("123");
} catch (ClassNotFoundException e) {

// TODO Auto-generated catch block
e.printStackTrace();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return conn;
}
public static void main(String[] args) {
ConnectionDB cd=new ConnectionDB();
Connection con=cd.getConn();
if(con==null){
System.out.println("连接失败");
}else{
System.out.println("连接成功");
}
}

异常：
java.sql.SQLException: Listener refused the connection with the following error:
ORA-12505, TNS:listener does not currently know of SID given in connect descriptor
The Connection descriptor used by the client was:
localhost:1521:orcl

at oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:111)
at oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:260)
at oracle.jdbc.driver.T4CConnection.logon(T4CConnection.java:386)
at oracle.jdbc.driver.PhysicalConnection.<init>(PhysicalConnection.java:413)
at oracle.jdbc.driver.T4CConnection.<init>(T4CConnection.java:164)
at oracle.jdbc.driver.T4CDriverExtension.getConnection(T4CDriverExtension.java:34)
at oracle.jdbc.driver.OracleDriver.connect(OracleDriver.java:752)
at java.sql.DriverManager.getConnection(DriverManager.java:582)
at java.sql.DriverManager.getConnection(DriverManager.java:185)
at train.dao.ConnectionDB.getConn(ConnectionDB.java:10)
at train.dao.ConnectionDB.main(ConnectionDB.java:38)
连接失败


初学者请高人指教，急！

[b5575233b3]

我已经导入了classes.jar包，代码我在别的机上使用过，可以连接，只是到我的机上就出现这样的问题，实在解决不了，诚心请求指点！
在线等！

[wula0010]

ORA-12505, TNS:listener does not currently know of SID given in connect descriptor

[完美灬缺陷]

http://qtlkw.iteye.com/blog/789195