execute Jar file - Java Reflection

Java examples for Reflection:Jar

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Description

execute Jar file

Demo Code

/*//w  w  w . j a  va 2 s  .c  om
 * Copyright @ 2006-2010 by The Jxva Framework Foundation
 * 
 * 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.java2s;
import java.io.File;

import java.io.IOException;

import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.ArrayList;

import java.util.jar.Attributes;

import java.util.jar.JarFile;

import java.util.jar.Manifest;

import java.util.zip.ZipFile;

public class Main {
    public static void exec(File jarFile, ArrayList<?> argsList,
            ClassLoader classLoader) throws IOException,
            ClassNotFoundException, SecurityException,
            NoSuchMethodException, IllegalArgumentException,
            IllegalAccessException, InvocationTargetException {
        String[] args = (String[]) argsList.toArray(new String[argsList
                .size()]);
        exec(jarFile, args, classLoader);
    }

    public static void exec(File jarFile, String[] args,
            ClassLoader classLoader) throws IOException,
            ClassNotFoundException, SecurityException,
            NoSuchMethodException, IllegalArgumentException,
            IllegalAccessException, InvocationTargetException {
        String mainClassName = getMainClassName(jarFile);
        if (mainClassName == null) {
            throw new ClassNotFoundException(
                    "Unable to extract name of Main-Class of "
                            + jarFile.getAbsolutePath());
        }
        Class<?> mainClass = classLoader.loadClass(mainClassName);
        Method mainMethod = mainClass.getMethod("main",
                new Class[] { String[].class });
        mainMethod.invoke(null, new Object[] { args });
    }

    /**
     * Extracts the name of the main class from the given jar file.
     * 
     * @param jarFile the jar file
     * @return the name of the main class from the given jar file, null when the jar does not have a manifest.
     * @throws IOException when the jar file could not be read
     */
    public static String getMainClassName(File jarFile) throws IOException {
        if (!jarFile.exists()) {
            throw new IllegalArgumentException("File ["
                    + jarFile.getAbsolutePath() + "] does not exist.");
        }
        JarFile input = new JarFile(jarFile, false, ZipFile.OPEN_READ);
        Manifest manifest = input.getManifest();
        if (manifest == null) {
            return null;
        }
        Attributes attributes = manifest.getMainAttributes();
        if (attributes != null) {
            return attributes.getValue("Main-Class");
        }
        return null;
    }
}

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