JAVA简易类加载器

package com.ghg.smartframework.helper;

import java.io.File;
import java.io.FileFilter;
import java.io.IOException;
import java.net.JarURLConnection;
import java.net.URL;
import java.util.Enumeration;
import java.util.HashSet;
import java.util.Set;
import java.util.jar.JarEntry;
import java.util.jar.JarFile;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * 类加载器
 * 
 * @author Administrator
 *
 */
public class ClassHelper {

    private static Logger logger = LoggerFactory.getLogger(ClassHelper.class);

    /**
     * 获取类加载器
     * 
     * @return
     */
    public static ClassLoader getClassLoad() {
        return Thread.currentThread().getContextClassLoader();
    }

    /**
     * 加载指定类
     * 
     * @param className
     *            全路径
     * @param isInitialized
     *            是否执行静态代码块, false不执行 true反之
     * @return
     */
    public static Class<?> loadClass(String className, boolean isInitialized) {
        Class<?> clz = null;
        try {
            clz = Class.forName(className, isInitialized, getClassLoad());
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
            logger.debug("loadClass  fail   {} --{} ", className, isInitialized);
        }
        return clz;
    }

    /**
     * 获取指定包下的所有类
     * 
     * @param packageName
     * @return
     */
    public static Set<Class<?>> getClassSet(String packageName) {
        Set<Class<?>> classSet = new HashSet<Class<?>>();

        try {
            // 获取资源地址
            Enumeration<URL> urls = getClassLoad().getResources(packageName.replace(".", "/"));
            // 循环
            while (urls.hasMoreElements()) {
                URL url = urls.nextElement();
                // 判断是否为空
                if (url != null) {
                    // 获取协议判断是否是文件
                    String protocol = url.getProtocol();

                    if (protocol.equals("file")) {
                        // 替换路径中的url编码 %20 unicode的编码,防止字符在传输中丢失
                        String packagePath = url.getPath().replaceAll("%20", "");
                        // 添加
                        addClass(classSet, packagePath, packageName);

                    } else if (protocol.equals("jar")) {

                        JarURLConnection jarURLConnection = (JarURLConnection) url.openConnection();

                        if (jarURLConnection != null) {

                            JarFile jarFile = jarURLConnection.getJarFile();

                            // 判断
                            if (jarFile != null) {
                                // 获取jar中的所有实体
                                Enumeration<JarEntry> jarEntries = jarFile.entries();

                                // 循环
                                while (jarEntries.hasMoreElements()) {

                                    JarEntry jarEntry = jarEntries.nextElement();
                                    // 判断
                                    String jarEntryName = jarEntry.getName();
                                    // 判断是不中class
                                    if (jarEntryName.endsWith(".class")) {
                                        // 获取类的全路径,把/替换为.
                                        String className = jarEntryName.substring(0, jarEntryName.lastIndexOf("."))
                                                .replace("/", ".");
                                        // 添加
                                        doAddClass(classSet, className);
                                    }

                                }

                            }

                        }

                    }

                }
            }

        } catch (IOException e) {
            e.printStackTrace();
            logger.debug(" get classSet fail");
        }

        return classSet;

    }

    /**
     * 添加
     * 
     * @param classSet
     * @param packagePath
     * @param packageName
     */
    public static void addClass(Set<Class<?>> classSet, String packagePath, String packageName) {

        File[] files = new File(packagePath).listFiles(new FileFilter() {
            // 过滤
            @Override
            public boolean accept(File file) {
                return (file.isFile() && file.getName().endsWith(".class") || file.isDirectory());
            }
        });

        if (files == null) {
            return;
        }

        for (File file : files) {

            String fileName = file.getName();
            // 是否为文件
            if (file.isFile()) {

                // 获取类名称
                String className = fileName.substring(0, fileName.lastIndexOf("."));

                if (StringHelper.isNotEmpty(packageName)) {
                    className = packageName + "." + className;
                }

                doAddClass(classSet, className);
            } else {
                // 不是文件
                String subPackagePath = fileName;

                if (StringHelper.isNotEmpty(packagePath)) {
                    // 拼接路径包名加上子包名
                    subPackagePath = packagePath + "/" + subPackagePath;
                }

                String subPackageName = fileName;

                if (StringHelper.isNotEmpty(packageName)) {
                    subPackageName = packageName + "." + subPackageName;
                }
                addClass(classSet, subPackagePath, subPackageName);
            }
        }

    }

    /**
     * 添加
     * 
     * @param classSet
     * @param className
     */
    public static void doAddClass(Set<Class<?>> classSet, String className) {

        Class<?> cls = loadClass(className, false);
        classSet.add(cls);
    }

    public static void main(String[] args) {

        String packageName = "com.ghg.smartframework";

        // Class<?> class1 = loadClass("com.ghg.smartframework.Test", false);

        Set<Class<?>> classSet = getClassSet(packageName);

        System.out.println(" classSet " + classSet.size());

        for (Class<?> cls : classSet) {

            System.out.println(" cls " + cls.getName() + "     " + cls.getSimpleName());
        }
    }
}