Converter for java.net.URL

(From J. Matthew Prior)

I would like to be able to serialize java.net.URLs. Currently it null pointers on deserialization.

public void testHttpURL() throws Exception {
URL http_url = new URL("http://www.apple.com/");
String xml = xstream.toXML(http_url);
URL read_back = (URL) xstream.fromXML(xml);
assertEquals(read_back, http_url);
}

public void testFileURL() throws Exception {
URL file_url = new URL("file:/usr/local/bin/");
String xml = xstream.toXML(file_url);
URL read_back = (URL) xstream.fromXML(xml);
assertEquals(read_back, file_url);
}

The URLStreamHandler is marked as transient, but is only lazily initialized in constructor or readObject() (neither of which get touched by xstream).

Here is a converter that should fix the problem:

/**

• a converter for {@link java.net.URL}

  that works around

• the fact that the embedded {@link java.net.URLStreamHandler}

  is

• transient and can only be initialized via a non-default constructor
• @author jmp
• @version $Revision$
  */
  public class URLConverter extends AbstractBasicConverter {

public boolean canConvert(Class type)

{ return type.equals(URL.class); }

protected Object fromString(String str) {
try

{ return new URL(str); }

catch (MalformedURLException e)

{ throw new ConversionException("Cannot parse url " + str, e); }

}

}