com.viaoa.jfc.editor.html.protocol.classpath.Handler Maven / Gradle / Ivy

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/*  Copyright 1999-2015 Vince Via [email protected]
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
    You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
    Unless required by applicable law or agreed to in writing, software
    distributed under the License is distributed on an "AS IS" BASIS,
    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    See the License for the specific language governing permissions and
    limitations under the License.
*/
package com.viaoa.jfc.editor.html.protocol.classpath;

import java.io.IOException; 
import java.net.InetAddress;
import java.net.URL; 
import java.net.URLConnection; 
import java.net.URLStreamHandler; 
import java.net.UnknownHostException;
import java.util.logging.Logger;


/**
 *  This is used to register a URL handler for url schema/protocol "classpath", 
 *  to load files from classpath. 
 *  This will allow html linkref to find files within the compiled code.
 *  
 *  Example:  format is "classpath://" + javapackage "/" + filename
 *  URL url = new URL("classpath://com.viaoa.jfc.editor.html.css/html.css");
 *  
 *  Ex:
 *  
 *  
 *  !!! NOTE !!!: must call static method "register()" or "jwsregister" to have this URL Handler used/registered.
 */  
 /*
    NOTES: 3 ways to "register" URL protocol handlers:
    
    1: System Property on the command line or as a JWS property
        -Djava.protocol.handler.pkgs=com.viaoa.jfc.editor.html.protocol
        
            * BUG: in 1.6, this will double launch and still not work
            * !! jws uses more then one classloader and the correct one is never set
                if starting a JWS app, it's best to call URLStreamHandler.jwsregister()
    
    2: have program set system property
        String sp = "com.viaoa.jfc.editor.html.protocol"; 
        System.setProperty( "java.protocol.handler.pkgs", s );
            * this does not work in jws (see #1)
    
    3: URL.setURLStreamHandlerFactory(...)
         this works, unless other code (ex: Tomcat, etc) has already called it.

    Note:  Hub2ImageHandler has static method that calls register.

 */
public class Handler extends URLStreamHandler { 
    private static boolean bRegister;
    private static boolean bRegisterResult;
    private static boolean bJWSRegistered;

    private static Logger LOG = Logger.getLogger(Handler.class.getName());
    
    
    

    /**
       This will need to set the system property, which is the same as runtime setting:
       -Djava.protocol.handler.pkgs=com.viaoa.jfc.editor.html.protocol
       Note: for JWS, use method jwsregister instead, since jws uses a classloader that can not be accessed.     
     */
    public static boolean register() {
        if (bRegister) return bRegisterResult;
        if (bJWSRegistered) return true;
        bRegister = true;
        LOG.fine("setting register using System.setProperty");
        
        String s = System.getProperty("java.protocol.handler.pkgs", "");
        if (s == null) s = "";
        if (s.length() > 0) s += "|";
        
        String sx = "com.viaoa.jfc.editor.html.protocol";
        if (s.indexOf(sx) >= 0) return true;
        
        
        System.setProperty( "java.protocol.handler.pkgs", s + sx );

        s = System.getProperty("java.protocol.handler.pkgs", "");
        if (s == null) s = "";
        int pos = (s.indexOf(sx));
        bRegisterResult = (pos >= 0);

        return bRegisterResult;
    }


    /**
     *  This should be used for JWS applications.  (see notes above)
     *  
     *  it is also necessary to call:
     *  System.setSecurityManager(null);  // needed for setting OA URL protocol handlers        
     *  
     *  
     */
    public static void jwsregister() {
        if (bJWSRegistered) return;
        bJWSRegistered = true;
        LOG.config("setting register for JWS");
        
        java.net.URL.setURLStreamHandlerFactory(new java.net.URLStreamHandlerFactory() {
            public java.net.URLStreamHandler createURLStreamHandler(final String protocol) {

                if(protocol == null) return null;
                if (protocol.equalsIgnoreCase("classpath")) {
                    return new Handler();
                }
                if (protocol.equalsIgnoreCase("oaproperty")) {
                    return new com.viaoa.jfc.editor.html.protocol.oaproperty.Handler();
                }
                return null;
            }
        });
    }
    
    
    // hack: so that the host name in the URL (which is the java classpath for this handler) is not resolved/looked-up.  
    //       the superClass uses the resolved address for hashing (ouch)
    private static InetAddress LocalHost;
    @Override 
    protected synchronized InetAddress getHostAddress(URL u) {
        if (LocalHost == null) {
            try {
                LocalHost = InetAddress.getLocalHost();
            }
            catch (UnknownHostException e) {
            }
        }
        return LocalHost;
    }    
    
    
    
    private static ClassLoader classLoader;
    @Override 
    protected URLConnection openConnection(URL u) throws IOException {
        LOG.finer("URL="+u);
        String path = u.getAuthority();
        if (path == null) path = "";
        if (path.length() > 0) {
            path = path.replace('.', '/');
        }
        path += u.getPath();  // includes a leading '/'
         
        
        if (classLoader == null) {
            classLoader = Handler.class.getClassLoader();
        }
        URL resourceUrl = classLoader.getResource(path);
        
        if (resourceUrl == null) {
            String s = "classpath resource not found, path="+path;
            LOG.fine(s);
            throw new IOException(s);
        }
        URLConnection con = resourceUrl.openConnection();
        return con;
    }
    

    
    
    public static void main(String[] args) throws Exception {
        boolean b = Handler.register();
        System.out.println("b="+b);
              
        URL url = new URL("classpath://com.viaoa.jfc.editor.html.css/html.css");
        System.out.println("url="+url);
        
        Object objx = url.getContent();
        System.out.println("content="+objx);
    }
}