[java] URL to load resources from the classpath in Java

I've created a class which helps to reduce errors in setting up custom handlers and takes advantage of the system property so there are no issues with calling a method first or not being in the right container. There's also an exception class if you get things wrong:

CustomURLScheme.java:
/*
 * The CustomURLScheme class has a static method for adding cutom protocol
 * handlers without getting bogged down with other class loaders and having to
 * call setURLStreamHandlerFactory before the next guy...
 */
package com.cybernostics.lib.net.customurl;

import java.net.URLStreamHandler;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

/**
 * Allows you to add your own URL handler without running into problems
 * of race conditions with setURLStream handler.
 * 
 * To add your custom protocol eg myprot://blahblah:
 * 
 * 1) Create a new protocol package which ends in myprot eg com.myfirm.protocols.myprot
 * 2) Create a subclass of URLStreamHandler called Handler in this package
 * 3) Before you use the protocol, call CustomURLScheme.add(com.myfirm.protocols.myprot.Handler.class);
 * @author jasonw
 */
public class CustomURLScheme
{

    // this is the package name required to implelent a Handler class
    private static Pattern packagePattern = Pattern.compile( "(.+\\.protocols)\\.[^\\.]+" );

    /**
     * Call this method with your handlerclass
     * @param handlerClass
     * @throws Exception 
     */
    public static void add( Class<? extends URLStreamHandler> handlerClass ) throws Exception
    {
        if ( handlerClass.getSimpleName().equals( "Handler" ) )
        {
            String pkgName = handlerClass.getPackage().getName();
            Matcher m = packagePattern.matcher( pkgName );

            if ( m.matches() )
            {
                String protocolPackage = m.group( 1 );
                add( protocolPackage );
            }
            else
            {
                throw new CustomURLHandlerException( "Your Handler class package must end in 'protocols.yourprotocolname' eg com.somefirm.blah.protocols.yourprotocol" );
            }

        }
        else
        {
            throw new CustomURLHandlerException( "Your handler class must be called 'Handler'" );
        }
    }

    private static void add( String handlerPackage )
    {
        // this property controls where java looks for
        // stream handlers - always uses current value.
        final String key = "java.protocol.handler.pkgs";

        String newValue = handlerPackage;
        if ( System.getProperty( key ) != null )
        {
            final String previousValue = System.getProperty( key );
            newValue += "|" + previousValue;
        }
        System.setProperty( key, newValue );
    }
}


CustomURLHandlerException.java:
/*
 * Exception if you get things mixed up creating a custom url protocol
 */
package com.cybernostics.lib.net.customurl;

/**
 *
 * @author jasonw
 */
public class CustomURLHandlerException extends Exception
{

    public CustomURLHandlerException(String msg )
    {
        super( msg );
    }

}

Examples related to java

Under what circumstances can I call findViewById with an Options Menu / Action Bar item? How much should a function trust another function How to implement a simple scenario the OO way Two constructors How do I get some variable from another class in Java? this in equals method How to split a string in two and store it in a field How to do perspective fixing? String index out of range: 4 My eclipse won't open, i download the bundle pack it keeps saying error log

Examples related to url

What is the difference between URL parameters and query strings? Allow Access-Control-Allow-Origin header using HTML5 fetch API File URL "Not allowed to load local resource" in the Internet Browser Slack URL to open a channel from browser Getting absolute URLs using ASP.NET Core How do I load an HTTP URL with App Transport Security enabled in iOS 9? Adding form action in html in laravel React-router urls don't work when refreshing or writing manually URL for public Amazon S3 bucket How can I append a query parameter to an existing URL?

Examples related to classloader

Caused By: java.lang.NoClassDefFoundError: org/apache/log4j/Logger How to get names of classes inside a jar file? How do I put all required JAR files in a library folder inside the final JAR file with Maven? Dealing with "Xerces hell" in Java/Maven? What is the difference between Class.getResource() and ClassLoader.getResource()? How to use ClassLoader.getResources() correctly? this.getClass().getClassLoader().getResource("...") and NullPointerException Load properties file in JAR? Difference between thread's context class loader and normal classloader URL to load resources from the classpath in Java