JarClassLoader.java

package com.xiaoleilu.hutool.lang;

import java.io.File;
import java.io.FileFilter;
import java.io.IOException;
import java.lang.reflect.Method;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLClassLoader;
import java.util.List;

import com.xiaoleilu.hutool.exceptions.UtilException;
import com.xiaoleilu.hutool.io.FileUtil;
import com.xiaoleilu.hutool.io.IoUtil;
import com.xiaoleilu.hutool.util.ClassUtil;

/**
 * 外部Jar的类加载器
 * 
 * @author Looly
 *
 */
public class JarClassLoader extends URLClassLoader {
	
	/**
	 * 加载Jar到ClassPath
	 * 
	 * @param jarFile jar文件或所在目录
	 * @return JarClassLoader
	 */
	public static JarClassLoader loadJar(File jarFile) {
		final JarClassLoader loader = new JarClassLoader();
		try {
			loader.addJar(jarFile);
		} finally {
			IoUtil.close(loader);
		}
		return loader;
	}
	
	/**
	 * 加载Jar文件到指定loader中
	 * @param loader {@link URLClassLoader}
	 * @param jarFile 被加载的jar
	 */
	public static void loadJar(URLClassLoader loader, File jarFile){
		try {
			final Method method = ClassUtil.getDeclaredMethod(URLClassLoader.class, "addURL", URL.class);
			if(null != method){
				method.setAccessible(true);
				final List<File> jars = loopJar(jarFile);
				for (File jar : jars) {
					ClassUtil.invoke(loader, method, new Object[]{jar.toURI().toURL()});
				}
			}
		} catch (IOException | ReflectiveOperationException e) {
			throw new UtilException(e);
		}
	}
	
	/**
	 * 加载Jar文件到System ClassLoader中
	 * @param jarFile 被加载的jar
	 * @return System ClassLoader
	 */
	public static URLClassLoader loadJarToSystemClassLoader(File jarFile){
		URLClassLoader urlClassLoader = (URLClassLoader) ClassLoader.getSystemClassLoader();
		loadJar(urlClassLoader, jarFile);
		return urlClassLoader;
	}

	// ------------------------------------------------------------------- Constructor start
	/**
	 * 构造
	 */
	public JarClassLoader() {
		this(new URL[] {});
	}

	/**
	 * 构造
	 * @param urls 被加载的URL
	 */
	public JarClassLoader(URL[] urls) {
		super(urls, ClassUtil.getClassLoader());
	}
	// ------------------------------------------------------------------- Constructor end

	/**
	 * 加载Jar文件，或者加载目录
	 * 
	 * @param jarFile jar文件或者jar文件所在目录
	 * @return this
	 */
	public JarClassLoader addJar(File jarFile) {
		final List<File> jars = loopJar(jarFile);
		try {
			for (File jar : jars) {
				super.addURL(jar.toURI().toURL());
			}
		} catch (MalformedURLException e) {
			throw new UtilException(e);
		}
		return this;
	}

	@Override
	public void addURL(URL url) {
		super.addURL(url);
	}

	// ------------------------------------------------------------------- Private method start
	/**
	 * 递归获得Jar文件
	 * 
	 * @param file jar文件或者包含jar文件的目录
	 * @return jar文件列表
	 */
	private static List<File> loopJar(File file) {
		return FileUtil.loopFiles(file, new FileFilter(){

			@Override
			public boolean accept(File file) {
				final String path = file.getPath();
				if (path != null && path.toLowerCase().endsWith(".jar")) {
					return true;
				}
				return false;
			}
		});
	}
	// ------------------------------------------------------------------- Private method end
}