Main.java Source code

Introduction

Here is the source code for Main.java

Source

//package com.java2s;

import java.net.MalformedURLException;
import java.net.URL;

public class Main {
    /**
     * Gets the base location of the given class.
     * <p>
     * If the class is directly on the file system (e.g.,
     * "/path/to/my/package/MyClass.class") then it will return the base directory
     * (e.g., "/path/to").
     * </p>
     * <p>
     * If the class is within a JAR file (e.g.,
     * "/path/to/my-jar.jar!/my/package/MyClass.class") then it will return the
     * path to the JAR (e.g., "/path/to/my-jar.jar").
     * </p>
     * 
     * @param className The name of the class whose location is desired.
     * @see FileUtils#urlToFile(URL) to convert the result to a {@link File}.
     */
    public static URL getLocation(final String className) {
        return getLocation(className, null);
    }

    /**
     * Gets the base location of the given class.
     * <p>
     * If the class is directly on the file system (e.g.,
     * "/path/to/my/package/MyClass.class") then it will return the base directory
     * (e.g., "/path/to").
     * </p>
     * <p>
     * If the class is within a JAR file (e.g.,
     * "/path/to/my-jar.jar!/my/package/MyClass.class") then it will return the
     * path to the JAR (e.g., "/path/to/my-jar.jar").
     * </p>
     * 
     * @param className The name of the class whose location is desired.
     * @param classLoader The class loader to use when loading the class.
     * @see FileUtils#urlToFile(URL) to convert the result to a {@link File}.
     */
    public static URL getLocation(final String className, final ClassLoader classLoader) {
        final Class<?> c = loadClass(className, classLoader);
        return getLocation(c);
    }

    /**
     * Gets the base location of the given class.
     * <p>
     * If the class is directly on the file system (e.g.,
     * "/path/to/my/package/MyClass.class") then it will return the base directory
     * (e.g., "file:/path/to").
     * </p>
     * <p>
     * If the class is within a JAR file (e.g.,
     * "/path/to/my-jar.jar!/my/package/MyClass.class") then it will return the
     * path to the JAR (e.g., "file:/path/to/my-jar.jar").
     * </p>
     * 
     * @param c The class whose location is desired.
     * @see FileUtils#urlToFile(URL) to convert the result to a {@link File}.
     */
    public static URL getLocation(final Class<?> c) {
        if (c == null)
            return null; // could not load the class

        // try the easy way first
        try {
            final URL codeSourceLocation = c.getProtectionDomain().getCodeSource().getLocation();
            if (codeSourceLocation != null)
                return codeSourceLocation;
        } catch (SecurityException e) {
            // NB: Cannot access protection domain.
        } catch (NullPointerException e) {
            // NB: Protection domain or code source is null.
        }

        // NB: The easy way failed, so we try the hard way. We ask for the class
        // itself as a resource, then strip the class's path from the URL string,
        // leaving the base path.

        // get the class's raw resource path
        final URL classResource = c.getResource(c.getSimpleName() + ".class");
        if (classResource == null)
            return null; // cannot find class resource

        final String url = classResource.toString();
        final String suffix = c.getCanonicalName().replace('.', '/') + ".class";
        if (!url.endsWith(suffix))
            return null; // weird URL

        // strip the class's path from the URL string
        final String base = url.substring(0, url.length() - suffix.length());

        String path = base;

        // remove the "jar:" prefix and "!/" suffix, if present
        if (path.startsWith("jar:"))
            path = path.substring(4, path.length() - 2);

        try {
            return new URL(path);
        } catch (MalformedURLException e) {
            e.printStackTrace();
            return null;
        }
    }

    /** Loads the class with the given name, or null if it cannot be loaded. */
    public static Class<?> loadClass(final String className) {
        return loadClass(className, null);
    }

    /** Loads the class with the given name, or null if it cannot be loaded. */
    public static Class<?> loadClass(final String className, final ClassLoader classLoader) {
        try {
            if (classLoader == null)
                return Class.forName(className);
            return classLoader.loadClass(className);
        } catch (final ClassNotFoundException e) {
            return null;
        }
    }
}