source: josm/src/org/openstreetmap/josm/plugins/PluginInformation.java@ 159

package org.openstreetmap.josm.plugins;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.net.URL;
import java.net.URLClassLoader;
import java.util.Map;
import java.util.TreeMap;
import java.util.jar.Attributes;
import java.util.jar.JarInputStream;
import java.util.jar.Manifest;

/**
 * Encapsulate general information about a plugin. This information is available
 * without the need of loading any class from the plugin jar file.
 *
 * @author imi
 */
public class PluginInformation {
        public final File file;
        public final String name;
        public final String className;
        public final String description;
        public final boolean early;
        public final String author;

        public final Map<String, String> attr = new TreeMap<String, String>();

        public PluginInformation(File file) {
                this.file = file;
                name = file.getName().substring(0, file.getName().length()-4);
                try {
                        JarInputStream jar = new JarInputStream(new FileInputStream(file));
                        Manifest manifest = jar.getManifest();
                        Attributes attr = manifest.getMainAttributes();
                        className = attr.getValue("Plugin-Class");
                        description = attr.getValue("Plugin-Description");
                        early = Boolean.parseBoolean(attr.getValue("Plugin-Early"));
                        author = attr.getValue("Author");
                        for (Object o : attr.keySet())
                                this.attr.put(o.toString(), attr.getValue(o.toString()));
                        jar.close();
                } catch (IOException e) {
                        throw new PluginException(null, name, e);
                }
        }

        /**
         * Load and instantiate the plugin
         */
        public PluginProxy load(Class<?> klass) {
                try {
                        return new PluginProxy(klass.newInstance(), this);
                } catch (Exception e) {
                        throw new PluginException(null, name, e);
                }
        }

        /**
         * Load the class of the plugin
         */
        public Class<?> loadClass() {
                try {
                        ClassLoader loader = URLClassLoader.newInstance(
                                        new URL[]{new URL(getURLString())},
                                        getClass().getClassLoader());
                        Class<?> realClass = Class.forName(className, true, loader);
                        return realClass;
                } catch (Exception e) {
                        throw new PluginException(null, name, e);
                }
        }

        private String getURLString() {
                if (System.getProperty("os.name").startsWith("Windows"))
                        return "file:/"+file.getAbsolutePath();
                return "file://"+file.getAbsolutePath();
        }
}