import java.io.File;
import java.io.FileFilter;
import java.net.URL;
import java.net.URLDecoder;
import java.util.ArrayList;
import java.util.Enumeration;
import java.util.List;

public class Commons {

    /**
     * 獲得包下面的所有的class
     *
     * @param
     *
     * @return List包含所有class的實(shí)例
     */

    public static List<Class<?>> getClasssFromPackage(String packageName) {
        List<Class<?>> clazzs = new ArrayList<>();
        // 是否循環(huán)搜索子包
        boolean recursive = true;
        // 包名對(duì)應(yīng)的路徑名稱
        String packageDirName = packageName.replace('.', '/');
        Enumeration<URL> dirs;

        try {
            dirs = Thread.currentThread().getContextClassLoader().getResources(packageDirName);
            while (dirs.hasMoreElements()) {

                URL url = dirs.nextElement();
                String protocol = url.getProtocol();

                if ("file".equals(protocol)) {
                    String filePath = URLDecoder.decode(url.getFile(), "UTF-8");
                    findClassInPackageByFile(packageName, filePath, recursive, clazzs);
                }
            }

        } catch (Exception e) {
            e.printStackTrace();
        }
        return clazzs;
    }

    /**
     * 在package對(duì)應(yīng)的路徑下找到所有的class
     */
    public static void findClassInPackageByFile(String packageName, String filePath, final boolean recursive,
                                                List<Class<?>> clazzs) {
        File dir = new File(filePath);
        if (!dir.exists() || !dir.isDirectory()) {
            return;
        }
        // 在給定的目錄下找到所有的文件卿泽，并且進(jìn)行條件過濾
        File[] dirFiles = dir.listFiles(new FileFilter() {

            public boolean accept(File file) {
                boolean acceptDir = recursive && file.isDirectory();// 接受dir目錄
                boolean acceptClass = file.getName().endsWith("class");// 接受class文件
                return acceptDir || acceptClass;
            }
        });

        for (File file : dirFiles) {
            if (file.isDirectory()) {
                findClassInPackageByFile(packageName + "." + file.getName(), file.getAbsolutePath(), recursive, clazzs);
            } else {
                String className = file.getName().substring(0, file.getName().length() - 6);
                try {
                    clazzs.add(Thread.currentThread().getContextClassLoader().loadClass(packageName + "." + className));
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        }
    }
}

使用方法：

  List<Class<?>> classList = Commons.getClasssFromPackage("com.demo.txt");
        
        for (Class<?> aClass : classList) {

            System.out.println(aClass);
        }