source: trunk/JFCMonitor/src/de/ugoe/cs/eventbench/jfcmonitor/JarLauncher.java @ 264

package de.ugoe.cs.eventbench.jfcmonitor;

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLClassLoader;
import java.util.jar.JarInputStream;
import java.util.jar.Manifest;

public class JarLauncher {

        String workingDir = System.getProperty("user.dir") + "/";
        String jarfile;
        String[] args;

        String[] classPath = new String[] {};
        String mainClassName = "";
        ClassLoader costumClassLoader;

        public class JarLaunchException extends Exception {

                private static final long serialVersionUID = 1L;

                public JarLaunchException() {
                        super();
                }

                public JarLaunchException(String string) {
                        super(string);
                }

                public JarLaunchException(Exception e) {
                        super(e);
                }

        }

        public JarLauncher(String jarfile, String[] args) {
                this.jarfile = jarfile;
                this.args = args;
        }

        public void exec() {
                try {
                        getInfoFromJar();
                        initClassLoader();
                        startSUT();
                } catch (JarLaunchException e) {
                        System.err.println("Failure to launch application.");
                        System.err.println(e.getMessage());
                }
        }

        private void getInfoFromJar() throws JarLaunchException {
                JarInputStream jarInputStream;
                try {
                        jarInputStream = new JarInputStream(new FileInputStream(workingDir
                                        + jarfile));
                } catch (FileNotFoundException e) {
                        throw new JarLaunchException(e);
                } catch (IOException e) {
                        throw new JarLaunchException(e);
                }
                Manifest manifest = jarInputStream.getManifest();
                mainClassName = manifest.getMainAttributes().getValue("Main-Class");
                String jarClassPath = manifest.getMainAttributes().getValue(
                                "Class-Path");
                String[] jarClassPathElements = jarClassPath.split(" ");
                classPath = new String[jarClassPathElements.length];
                for (int i = 0; i < jarClassPathElements.length; i++) {
                        classPath[i] = "file:" + workingDir + jarClassPathElements[i];
                }
        }

        private void initClassLoader() throws JarLaunchException {
                URLClassLoader classLoader = (URLClassLoader) ClassLoader
                                .getSystemClassLoader();
                Method method;
                try {
                        method = URLClassLoader.class.getDeclaredMethod("addURL",
                                        new Class[] { URL.class });
                } catch (SecurityException e) {
                        throw new JarLaunchException(
                                        "addURL method of URLClassLoader not accessible via reflection.");
                } catch (NoSuchMethodException e) {
                        throw new JarLaunchException(
                                        "URLClassLoader does not have addURL method. Should be impossible!!");
                }
                method.setAccessible(true);

                try {
                        method.invoke(classLoader, new Object[] { new URL("file:"
                                        + workingDir + jarfile) });
                        for (String element : classPath) {
                                method.invoke(classLoader, new Object[] { new URL(element) });
                        }
                } catch (IllegalArgumentException e) {
                        throw new JarLaunchException(
                                        "Illegal arguments for addURL method. Should be impossible!!");
                } catch (MalformedURLException e) {
                        throw new JarLaunchException(e);
                } catch (IllegalAccessException e) {
                        throw new JarLaunchException(
                                        "addURL method of URLClassLoader not accessible via reflection.");
                } catch (InvocationTargetException e) {
                        e.printStackTrace();
                }
        }

        private void startSUT() throws JarLaunchException {
                Class<?> mainClass;
                try {
                        mainClass = Class.forName(mainClassName);
                } catch (ClassNotFoundException e) {
                        throw new JarLaunchException("Main class not found: "
                                        + mainClassName);
                }
                Method mainMethod;
                try {
                        mainMethod = mainClass.getMethod("main",
                                        new Class[] { String[].class });
                } catch (SecurityException e) {
                        throw new JarLaunchException("Main method not accessible.");
                } catch (NoSuchMethodException e) {
                        throw new JarLaunchException("Main method not found.");
                }
                try {
                        mainMethod.invoke(null, new Object[] { args });
                } catch (IllegalArgumentException e) {
                        throw new JarLaunchException(
                                        "Illegal arguments for main method. Should be impossible!!");
                } catch (IllegalAccessException e) {
                        throw new JarLaunchException("Main method not accessible.");
                } catch (InvocationTargetException e) {
                        throw new JarLaunchException(e);
                }
        }
}