how to generate x.509 certificate?

[L Willie]

    
import java.io.InputStream;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.ObjectOutputStream;
import java.io.BufferedOutputStream;
import java.security.cert.X509Certificate;
import java.security.cert.Certificate;
import java.security.cert.CertificateFactory;
import java.util.Collection;
import java.util.Iterator;
 
public class generateCert {
  public static void main(String args[]) throws Exception {
 
FileOutputStream fos = new FileOutputStream("C:/certChain.db");  
        ObjectOutputStream oos = new ObjectOutputStream(new   BufferedOutputStream(fos));
 
    
 FileInputStream fis = new FileInputStream("C:/certChain.db");
 CertificateFactory cf = CertificateFactory.getInstance("X.509");
 Collection c = cf.generateCertificates(fis);
 
 Iterator i = c.iterator();
 while (i.hasNext()) {
    X509Certificate cert = (X509Certificate)i.next();
    System.out.println(cert);
 }
 
  }
}

above code could create certChain.db as normal.however can't generate x.509 certificate to the output file- "certChain.db".

[Ulf Dittmer]

What does "can't generate" mean? What exactly happens if you try?

[Matteo Di Furia]

How comes you're reading (FileInputStream) and probably wanting to write (FileOutputStream) to the same file (C:\chainCert.db)?
Other than this, I don't know if I got correctly what you're asking, but if you don't write something in the output stream (oos.write(some_obj)) you'll get nothing in the file (remember to flush and close).

[L Willie]

Originally posted by Matteo Di Furia:
How comes you're reading (FileInputStream) and probably wanting to write (FileOutputStream) to the same file (C:\chainCert.db)?
Other than this, I don't know if I got correctly what you're asking, but if you don't write something in the output stream (oos.write(some_obj)) you'll get nothing in the file (remember to flush and close).

can't generate means i get nothing on the file (C:\chainCert.db).

actually i want to modify from following code

    
import java.awt.Polygon;
import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
public class polygon {
  public static void main(String[] args) {
    int[] x = new int[] { 1, 2, 3 };
    int[] y = new int[] { 4, 5, 6 };
    Polygon polygon = new Polygon(x, y, x.length);
    try {
      ObjectOutputStream objectOut = new ObjectOutputStream(new BufferedOutputStream(
          new FileOutputStream("Polygons.dat")));
      objectOut.writeObject(polygon);
      objectOut.close();
    } catch (IOException e) {
      e.printStackTrace(System.err);
    }
    try {
      ObjectInputStream objectIn = new ObjectInputStream(new BufferedInputStream(
          new FileInputStream("Polygons.dat")));
      Polygon theLine = (Polygon) objectIn.readObject();
      System.out.println(theLine);
      objectIn.close();
    } catch (Exception e) {
      e.printStackTrace(System.err);
    }
 
  }
}

that is generate certificate before write oubject,after the oubject writeOut to file C:\chainCert.db,reading the cert from the file.
however i confuse by this code that i found from internet.it seams generateCert during read file,not before write out file.

    
FileInputStream inStream = new FileInputStream(args[0]);
CertificateFactory cf = CertificateFactory.getInstance("X.509");
X509Certificate cert = (X509Certificate)cf.generateCertificate(inStream);
inStream.close();

[ October 03, 2008: Message edited by: L Willie ]