FWJavaScriptClassLoader.java

package vrml;
import java.io.*;
import java.net.URL;
import java.net.SocketPermission;
import java.net.MalformedURLException;
import java.util.Enumeration;
import java.util.NoSuchElementException;
import java.util.PropertyPermission;
import java.security.*;
import java.security.cert.Certificate;


public final class FWJavaScriptClassLoader extends SecureClassLoader {
    URL baseURL;
    CodeSource myCodeSource;


    public FWJavaScriptClassLoader(String url) {
        System.out.println ("new FWJavaScriptClassLoader - url is " + url);
        try {
            baseURL = new java.net.URL(url);

            myCodeSource = new CodeSource(baseURL, (Certificate[]) null);
        } catch (MalformedURLException ex) {
            throw new InternalError("Script URL malformed: "+url);
        }
    }

    protected Class findClass(String name)
        throws ClassNotFoundException
    {
        System.err.println("LOADING CLASS '"+name+"'");
        try {
            byte[] b = readFile(name.replace('.', '/') + ".class");
            return defineClass(name, b, 0, b.length, myCodeSource);
        } catch (IOException e) {
            throw new ClassNotFoundException(name);
        }
    }

    private static final String props[] = {
        "file.separator",
        "path.separator",
        "java.class.version",
        "java.vendor",
        "java.version",
        "java.specification.name",
        "java.specification.vendor",
        "java.specification.version",
        "java.vendor.url",
        "java.vm.name",
        "java.vm.vendor",
        "java.vm.version",
        "java.vm.specification.name",
        "java.vm.specification.vendor",
        "java.vm.specification.version",
        "line.separator",
        "os.name",
        "os.arch",
        "os.version"
    };

    protected PermissionCollection getPermissions(CodeSource codesource) {
        Permissions perms = new Permissions();
        URL url = codesource.getLocation();
        perms.add(new SocketPermission(url.getHost(), "connect,accept"));
        if (url.getProtocol().equals("file")) {
            /* local script */
            String path = url.getFile().replace('/', File.separatorChar);
            path = path.substring(0, path.lastIndexOf(File.separatorChar)+1);
            perms.add(new FilePermission(path+"*", "read,write,delete"));
        }
        for (int i = 0; i < props.length; i++)
            perms.add(new PropertyPermission(props[i], "read"));
        //System.err.println("Script permission are "+perms);
        return perms;
    }

    private byte[] readFile(String name) throws IOException
    {
        InputStream is = getResourceAsStream(name);
        ByteArrayOutputStream bao = new ByteArrayOutputStream();
        byte[] buff = new byte[4096];
        int len;
        while ((len = is.read(buff)) > 0)
            bao.write(buff, 0, len);
        return bao.toByteArray();
    }

    protected URL findResource(String name)
    {
        try {
            System.err.println("LOADING RESOURCE '"+name+"'");
            return new URL(baseURL, name);
        } catch (MalformedURLException ex) {
            return null;
        }
    }

    protected Enumeration findResources(String name) throws IOException
    {
        final URL url = new URL(baseURL, name);
        return new Enumeration() {
                boolean hasMore = true;
                public boolean hasMoreElements() {
                    return hasMore;
                }
                public Object nextElement() {
                    if (!hasMore)
                        throw new NoSuchElementException();
                    hasMore = false;
                    return url;
                }
            };
    }
}