访问被拒绝（“java.io.FilePermission”“execute”）

Question

I am beginner.it is first applet that i writing

i want run exe application with applet

java code

 package appletexample;

import java.io.*;
import java.awt.*;
import java.applet.Applet;

public class Welcome extends Applet {

    public void init() {
        String execommand = "C:\\windows\\notepad.exe" ;
        try {
            Process proc =  Runtime.getRuntime().exec(execommand) ;
        }
        catch(IOException ieo) {
            System.out.println("Problem starting " + execommand) ;
        }
    }
} 

java.policy.applet

grant {
  permission java.security.AllPermission;
};

i run this code in eclipse Run As->Java Applet worked and opened NotePade but when Export->Jar File(with .classPath,.project,java.policy.applet) and use in

Html

<applet archive="test.jar" code="appletexample/Welcome.class"  width=550 height=300>

in firefox say error access denied ("java.io.FilePermission" "execute")? how can fix this problem? download my java and Html code

Answer 1

As beginner you should start with something much much simpler. When you play with Applets not all security rules apply. But when you come to real world (Browser in your case or, in other terms, sandbox) security rules are in force to prevent your code from harming the host computer.

What you are doing - you are running some program on the client computer when the client opens your web page with an Applet. That what viruses do. People will not want to allow it.

Of course you can the use Signed Applet approach or other ways to run program on another computer, but is it your goal? If it is to learn basics, then run easy stuff. Eventually, you will understand JNLP (Java Web Start) and other methods useful for you and your clients.

Answer 2

I assume that you just want to practice how to write a applet. For development purpose, you can create a keystore and then use it to sign your applet.jar.

Go: Start Menu > Execute > cmd.exe

Input:

cd /
keytool -genkey -dname "cn=CN, ou=OU, o=O, l=L, st=ST, c=C" -alias mykey -keypass mypass -keystore mystore -validity 3650 -storepass mypass
jarsigner -keystore c:\mystore -storepass mypass C:\path\to\applet.jar mykey

Then:

Refresh your HTML page.