javabean连接数据库出错问题

private String url = "jdbc:weblogic:mssqlserver4:";
private String serverName = "VICTORY"; //缺省配置参数
private String portNumber = "1433";
private String databaseName = "bbs";
private String userName = "sa";
private String password = "3989632";

private java.sql.Connection con = null;
private Statement stmt = null;
private Statement stmtNum = null;
private PreparedStatement pstmt = null;
private ResultSet rs = null;
private int resultNum = 0;
private ResultSet countRs = null;
private int rsNum = 0;
public int stateNum1;


/** 构造函数 **/
public OpenDb() {
stateNum1 = 1;
try{
con = java.sql.DriverManager.getConnection(getConnectionUrl(),userName,password);
stmt = con.createStatement();
}catch(Exception e){
e.printStackTrace();
System.out.println("数据库连接错误 : " + e.getMessage());
}


}

private String getConnectionUrl(){
return url + databaseName + "@" + serverName;
}


如上一段连接数据库的程序段，我用jdbc连接sqlserver，平台是weblogic，但是老提示出错“数据库连接错误 : No suitable driver”