htp.print(trunc((sysdate - to_date('01-01-1970','dd-mm-yyyy'))*24*60*60));

htp.print(getTime);

Output:
1163687199 
1163708799 

CREATE OR REPLACE function getTime
RETURN VARCHAR2 AS LANGUAGE JAVA
NAME 'timeFormat.getTimeFormat() return java.lang.String';
/


CREATE OR REPLACE AND RESOLVE JAVA SOURCE NAMED "timeFormat" AS
import java.util.*;


public class timeFormat 
  {  
    public String getTimeFormat(Date time) 
	  {
       // Create a buffer in which to format the data to sign.
	   
       StringBuffer buffer = new StringBuffer();
		
       // Add the appropriately formatted time stamp. Note that
       // the time stamp is expressed in seconds, not milliseconds.

       buffer.append(time.getTime() / 1000);
        
       return buffer.toString();
      }

   public static String getTimeFormat()
     {
      timeFormat timeFormat = new timeFormat(); 
      Date now = new Date(); 
      String returnValue = timeFormat.getTimeFormat(now);
      return returnValue;
     }
  }
;
/