您可能应该看看开源的Reflections库。有了它，你可以很容易地实现你想要的。

首先，设置反射索引(这有点乱，因为搜索所有类默认是禁用的):

List<ClassLoader> classLoadersList = new LinkedList<ClassLoader>();
classLoadersList.add(ClasspathHelper.contextClassLoader());
classLoadersList.add(ClasspathHelper.staticClassLoader());

Reflections reflections = new Reflections(new ConfigurationBuilder()
    .setScanners(new SubTypesScanner(false /* don't exclude Object.class */), new ResourcesScanner())
    .setUrls(ClasspathHelper.forClassLoader(classLoadersList.toArray(new ClassLoader[0])))
    .filterInputsBy(new FilterBuilder().include(FilterBuilder.prefix("org.your.package"))));

然后你可以查询给定包中的所有对象:

Set<Class<?>> classes = reflections.getSubTypesOf(Object.class);

不使用任何额外的库:

package test;

import java.io.DataInputStream;
import java.io.InputStream;
import java.net.URL;
import java.util.ArrayList;
import java.util.List;

public class Test {
    public static void main(String[] args) throws Exception{
        List<Class> classes = getClasses(Test.class.getClassLoader(),"test");
        for(Class c:classes){
            System.out.println("Class: "+c);
        }
    }

    public static List<Class> getClasses(ClassLoader cl,String pack) throws Exception{

        String dottedPackage = pack.replaceAll("[/]", ".");
        List<Class> classes = new ArrayList<Class>();
        URL upackage = cl.getResource(pack);

        DataInputStream dis = new DataInputStream((InputStream) upackage.getContent());
        String line = null;
        while ((line = dis.readLine()) != null) {
            if(line.endsWith(".class")) {
               classes.add(Class.forName(dottedPackage+"."+line.substring(0,line.lastIndexOf('.'))));
            }
        }
        return classes;
    }
}

如果您不使用任何动态类加载器，您可以搜索类路径，并为每个条目搜索目录或JAR文件。

在使用Maven时，Aleksander Blomskøld的解决方案对我的参数化测试@RunWith(parameterized .class)不起作用。正确命名了测试，并显示了找到但未执行的位置:

-------------------------------------------------------
T E S T S
-------------------------------------------------------
Running some.properly.named.test.run.with.maven.SomeTest
Tests run: 0, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.123 sec

这里也报道了类似的问题。

在我的例子中，@Parameters是在包中创建每个类的实例。这些测试在IDE中本地运行时运行良好。然而，当运行Maven时，在Aleksander Blomskøld的解决方案中没有找到类。

我确实用以下剪辑完成了它，灵感来自David Pärsson对Aleksander Blomskøld回答的评论:

Reflections reflections = new Reflections(new ConfigurationBuilder()
            .setScanners(new SubTypesScanner(false /* don't exclude Object.class */), new ResourcesScanner())
            .addUrls(ClasspathHelper.forJavaClassPath()) 
            .filterInputsBy(new FilterBuilder()
            .include(FilterBuilder.prefix(basePackage))));

Set<Class<?>> subTypesOf = reflections.getSubTypesOf(Object.class);

如果你在Spring-land，你可以使用PathMatchingResourcePatternResolver;

  PathMatchingResourcePatternResolver resolver = new PathMatchingResourcePatternResolver();
  Resource[] resources = resolver.getResources("classpath*:some/package/name/*.class");

    Arrays.asList(resources).forEach(r->{
        ...
    });

你需要查找类路径中的每个类装入器条目:

    String pkg = "org/apache/commons/lang";
    ClassLoader cl = ClassLoader.getSystemClassLoader();
    URL[] urls = ((URLClassLoader) cl).getURLs();
    for (URL url : urls) {
        System.out.println(url.getFile());
        File jar = new File(url.getFile());
        // ....
    }   

如果条目是目录，只需在右边的子目录中查找:

if (jar.isDirectory()) {
    File subdir = new File(jar, pkg);
    if (!subdir.exists())
        continue;
    File[] files = subdir.listFiles();
    for (File file : files) {
        if (!file.isFile())
            continue;
        if (file.getName().endsWith(".class"))
            System.out.println("Found class: "
                    + file.getName().substring(0,
                            file.getName().length() - 6));
    }
}   

如果条目是文件，并且它是jar，检查它的ZIP条目:

else {
    // try to open as ZIP
    try {
        ZipFile zip = new ZipFile(jar);
        for (Enumeration<? extends ZipEntry> entries = zip
                .entries(); entries.hasMoreElements();) {
            ZipEntry entry = entries.nextElement();
            String name = entry.getName();
            if (!name.startsWith(pkg))
                continue;
            name = name.substring(pkg.length() + 1);
            if (name.indexOf('/') < 0 && name.endsWith(".class"))
                System.out.println("Found class: "
                        + name.substring(0, name.length() - 6));
        }
    } catch (ZipException e) {
        System.out.println("Not a ZIP: " + e.getMessage());
    } catch (IOException e) {
        System.err.println(e.getMessage());
    }
}

现在，一旦包中有了所有的类名，就可以尝试用反射加载它们，并分析它们是类还是接口等等。