参见英文答案 >
Can you find all classes in a package using reflection?21
所以我有一个包含扩展JPanel的类的包,我想将它们作为选项卡动态添加.一开始我使用了一个工厂,我注册了所有的类,它的工作,但现在我想加载包中的所有类,而不知道他们的名字.我已经尝试了几件事情,包括
Reflections library(我觉得很混乱),我无法让他们上班.我感谢任何帮助.
这是我的一个尝试:
public static void registerTab() { String pkg = TabA.class.getPackage().getName(); String relPath = pkg.replace('.','/'); URL resource = ClassLoader.getSystemClassLoader().getResource(relPath); if (resource == null) { throw new RuntimeException("Unexpected problem: No resource for " + relPath); } File f = new File(resource.getPath()); String[] files = f.list(); for (int i = 0; i < files.length; i++) { String fileName = files[i]; String className = null; String fileNm = null; if (fileName.endsWith(".class")) { fileNm = fileName.substring(0,fileName.length() - 6); className = pkg + '.' + fileNm; } if (className != null) { if (!tabClasses.containsKey(className)) tabClasses.put(fileNm,className); } } }
解决方法
这是我开发的一个定制解决方案来查找包的所有类:
public class ClassFinder { private static final char PKG_SEPARATOR = '.'; private static final char DIR_SEPARATOR = '/'; private static final String CLASS_FILE_SUFFIX = ".class"; private static final String BAD_PACKAGE_ERROR = "Unable to get resources from path '%s'. Are you sure the package '%s' exists?"; public static List<Class<?>> find(String scannedPackage) { String scannedPath = scannedPackage.replace(PKG_SEPARATOR,DIR_SEPARATOR); URL scannedUrl = Thread.currentThread().getContextClassLoader().getResource(scannedPath); if (scannedUrl == null) { throw new IllegalArgumentException(String.format(BAD_PACKAGE_ERROR,scannedPath,scannedPackage)); } File scannedDir = new File(scannedUrl.getFile()); List<Class<?>> classes = new ArrayList<Class<?>>(); for (File file : scannedDir.listFiles()) { classes.addAll(find(file,scannedPackage)); } return classes; } private static List<Class<?>> find(File file,String scannedPackage) { List<Class<?>> classes = new ArrayList<Class<?>>(); String resource = scannedPackage + PKG_SEPARATOR + file.getName(); if (file.isDirectory()) { for (File child : file.listFiles()) { classes.addAll(find(child,resource)); } } else if (resource.endsWith(CLASS_FILE_SUFFIX)) { int endIndex = resource.length() - CLASS_FILE_SUFFIX.length(); String className = resource.substring(0,endIndex); try { classes.add(Class.forName(className)); } catch (ClassNotFoundException ignore) { } } return classes; } }
然后,只需使用:
List<Class<?>> classes = ClassFinder.find("com.package");