Controle de Acesso no Java Web Start

import java.io.*;
import javax.swing.JOptionPane;

public class _escreverAA {

	private static RandomAccessFile arquivo;

	public _escreverAA() {

		try {
			arquivo = new RandomAccessFile(new File("arquivo.txt"), "rw");
			JOptionPane.showMessageDialog(null, "acho arquivo", "", JOptionPane.ERROR_MESSAGE);
		} catch (FileNotFoundException e) {
			JOptionPane.showMessageDialog(null, e.getMessage(), "erro 1 nao acho", JOptionPane.ERROR_MESSAGE);
		}

		try {
			arquivo.writeInt(1);
			arquivo.writeDouble(1984);
			arquivo.writeChar('T');
			arquivo.writeUTF("teste");
			JOptionPane.showMessageDialog(null, "gravo arquivo", "", JOptionPane.ERROR_MESSAGE);
		} catch (IOException e) {
			JOptionPane.showMessageDialog(null, e.getMessage(), "erro 2 gravo", JOptionPane.ERROR_MESSAGE);
		}
	}
}

Exception in thread "AWT-EventQueue-0" java.security.AccessControlException: access denied (java.io.FilePermission arquivo.txt read)
	at java.security.AccessControlContext.checkPermission(Unknown Source)
	at java.security.AccessController.checkPermission(Unknown Source)
	at java.lang.SecurityManager.checkPermission(Unknown Source)
	at java.lang.SecurityManager.checkRead(Unknown Source)
	at java.io.RandomAccessFile.<init>(Unknown Source)
	at _escreverAA.<init>(_escreverAA.java:12)
	at Acesso$1.actionPerformed(Acesso.java:23)
	at javax.swing.AbstractButton.fireActionPerformed(Unknown Source)
	at javax.swing.AbstractButton$Handler.actionPerformed(Unknown Source)
	at javax.swing.DefaultButtonModel.fireActionPerformed(Unknown Source)
	at javax.swing.DefaultButtonModel.setPressed(Unknown Source)
	at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(Unknown Source)
	at java.awt.Component.processMouseEvent(Unknown Source)
	at javax.swing.JComponent.processMouseEvent(Unknown Source)
	at java.awt.Component.processEvent(Unknown Source)
	at java.awt.Container.processEvent(Unknown Source)
	at java.awt.Component.dispatchEventImpl(Unknown Source)
	at java.awt.Container.dispatchEventImpl(Unknown Source)
	at java.awt.Component.dispatchEvent(Unknown Source)
	at java.awt.LightweightDispatcher.retargetMouseEvent(Unknown Source)
	at java.awt.LightweightDispatcher.processMouseEvent(Unknown Source)
	at java.awt.LightweightDispatcher.dispatchEvent(Unknown Source)
	at java.awt.Container.dispatchEventImpl(Unknown Source)
	at java.awt.Window.dispatchEventImpl(Unknown Source)
	at java.awt.Component.dispatchEvent(Unknown Source)
	at java.awt.EventQueue.dispatchEvent(Unknown Source)
	at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
	at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
	at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
	at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
	at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
	at java.awt.EventDispatchThread.run(Unknown Source)

<?xml version="1.0" encoding="utf-8"?> 

<jnlp 
	spec="1.0+" 
	codebase="http://www.informaticajm.com.br/tutorialjws" href="teste.jnlp"> 

		<information> 
			<title>teste</title> 
			<vendor>teste</vendor> 
			<homepage href="http://www.informaticajm.com.br/tutorialjws/index.html"/>

			<description>teste</description> 
			<description kind="short">teste</description> 
			<icon href="images/logo.jpg"/> 
			<offline-allowed/> 
		</information> 

		<resources> 
			<j2se version="1.6+" href="http://java.sun.com/products/autodl/j2se"/> 

			<jar href="teste1.jar"/> 
			<property name="myProperty" value="teste"/> 

		</resources> 

		<application-desc main-class="Acesso"/> 
   		</application-desc>

		<security>
			<all-permissions/>
		</security>
</jnlp>