You need to add a protocol handler for "data:" so an URL/URLConnection can be opened for it. Alternatively you could create some protocol handler "resource:" for class path resources.
You need a package data with a class Handler (fixed name convention!). This will be the factory class for "data:" return an URLConnection. We will create DataConnection for that.
Installing a protocol handler can be done via System.setProperty. Here I provided Handler.install(); to do that in a generic way.
package test1.data;
import java.io.IOException;
import java.net.URL;
import java.net.URLConnection;
import java.net.URLStreamHandler;
public class Handler extends URLStreamHandler {
@Override
protected URLConnection openConnection(URL u) throws IOException {
return new DataConnection(u);
}
public static void install() {
String pkgName = Handler.class.getPackage().getName();
String pkg = pkgName.substring(0, pkgName.lastIndexOf('.'));
String protocolHandlers = System.getProperty("java.protocol.handler.pkgs", "");
if (!protocolHandlers.contains(pkg)) {
if (!protocolHandlers.isEmpty()) {
protocolHandlers += "|";
}
protocolHandlers += pkg;
System.setProperty("java.protocol.handler.pkgs", protocolHandlers);
}
}
}
The URLConnection gives an InputStream to the bytes:
package test1.data;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import java.net.URLConnection;
import javax.xml.bind.DatatypeConverter;
public class DataConnection extends URLConnection {
public DataConnection(URL u) {
super(u);
}
@Override
public void connect() throws IOException {
connected = true;
}
@Override
public InputStream getInputStream() throws IOException {
String data = url.toString();
data = data.replaceFirst("^.*;base64,", "");
System.out.println("Data: " + data);
byte[] bytes = DatatypeConverter.parseBase64Binary(data);
return new ByteArrayInputStream(bytes);
}
}
The clever thing here is to use Base64 decoding of DatatypeConverter in standard Java SE.
P.S.
Nowadays one would use Base64.getEncoder().encode(...).
与恶龙缠斗过久,自身亦成为恶龙；凝视深渊过久,深渊将回以凝视…
