org.danann.cernunnos.runtime.Main.java Source code

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Here is the source code for org.danann.cernunnos.runtime.Main.java

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/*
 * Copyright 2007 Andrew Wills
 *
 * 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 org.danann.cernunnos.runtime;

import java.io.File;
import java.net.URL;
import java.net.URLStreamHandler;
import java.net.URLStreamHandlerFactory;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

public final class Main {

    public static void main(String[] args) {

        Log log = LogFactory.getLog(ScriptRunner.class);

        // Put some whitespace between the command and the output...
        System.out.println("");

        // Register custom protocol handlers...
        try {
            URL.setURLStreamHandlerFactory(new URLStreamHandlerFactoryImpl());
        } catch (Throwable t) {
            log.warn("Cernunnos was unable to register a URLStreamHandlerFactory.  "
                    + "Custom URL protocols may not work properly (e.g. classpath://, c:/).  "
                    + "See stack trace below.", t);
        }

        // Establish CRN_HOME...
        String crnHome = System.getenv("CRN_HOME");
        if (crnHome == null) {
            if (log.isDebugEnabled()) {
                log.debug("The CRN_HOME environment variable is not defined;  "
                        + "this is completely normal for embedded applications " + "of Cernunnos.");
            }
        }

        // Look at the specified script:  might it be in the bin/ directory?
        String location = args[0];
        try {
            // This is how ScriptRunner will attempt to locate the script file...
            URL u = new URL(new File(".").toURI().toURL(), location);
            if (u.getProtocol().equals("file")) {
                // We know the specified resource is a local file;  is it either 
                // (1) absolute or (2) relative to the directory where Java is 
                // executing?
                if (!new File(u.toURI()).exists() && crnHome != null) {
                    // No.  And what's more, 'CRN_HOME' is defined.  In this case 
                    // let's see if the specified script *is* present in the bin/ 
                    // directory.
                    StringBuilder path = new StringBuilder();
                    path.append(crnHome).append(File.separator).append("bin").append(File.separator)
                            .append(location);
                    File f = new File(path.toString());
                    if (f.exists()) {
                        // The user is specifying a Cernunnos script in the bin/ directory...
                        location = f.toURI().toURL().toExternalForm();
                        if (log.isInfoEnabled()) {
                            log.info("Resolving the specified Cernunnos document "
                                    + "to a file in the CRN_HOME/bin directory:  " + location);
                        }
                    }
                }
            }
        } catch (Throwable t) {
            // Just let this pass -- genuine issues will be caught & reported shortly...
        }

        // Analyze the command-line arguments...
        RuntimeRequestResponse req = new RuntimeRequestResponse();
        switch (args.length) {
        case 0:
            // No file provided, can't continue...
            System.out.println("Usage:\n\n\t>crn [script_name] [arguments]");
            System.exit(0);
            break;
        default:
            for (int i = 1; i < args.length; i++) {
                req.setAttribute("$" + i, args[i]);
            }
            break;
        }

        ScriptRunner runner = new ScriptRunner();
        runner.run(location, req);

    }

    /*
     * Nested Types.
     */

    private static final class URLStreamHandlerFactoryImpl implements URLStreamHandlerFactory {

        public URLStreamHandler createURLStreamHandler(String protocol) {

            // Assertions.
            if (protocol == null) {
                String msg = "Argument 'protocol' cannot be null.";
                throw new IllegalArgumentException(msg);
            }

            URLStreamHandler rslt = null;

            if (protocol.equals("classpath")) {
                rslt = new ClasspathURLStreamHandler();
            } else if (protocol.matches("\\A[a-zA-Z]\\z")) {
                rslt = new WindowsDriveURLStreamHandler();
            }

            return rslt;

        }

    }

}