获取指定包下的所有类

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因为包多的话，遍历查找会损耗性能。所以我想只加载某个包，然后查找类。请问可以实现吗？最好能给一些示例代码。谢谢。

2012-07-11 13:06网友采纳

private static List<Class> getClassesByPackageName(String packageName)   throws IOException, ClassNotFoundException {  ClassLoader classLoader = Thread.currentThread()    .getContextClassLoader();  String path = packageName.replace('.', '/');  Enumeration<URL> resources = classLoader.getResources(path);  List<File> dirs = new ArrayList<File>();  while (resources.hasMoreElements()) {   URL resource = resources.nextElement();   dirs.add(new File(resource.getFile()));  }  ArrayList<Class> classes = new ArrayList<Class>();  for (File directory : dirs) {   classes.addAll(findClasses(directory, packageName));  }  return classes; } private static List<Class> findClasses(File directory, String packageName)   throws ClassNotFoundException {  List<Class> classes = new ArrayList<Class>();  if (!directory.exists()) {   return classes;  }  File[] files = directory.listFiles();  for (File file : files) {   if (file.isDirectory()) {    // 递归查找文件夹【即对应的包】下面的所有文件    assert !file.getName().contains(".");    classes.addAll(findClasses(file, packageName + '.'      + file.getName()));   } else if (file.getName().endsWith(".class")) {    classes.add(Class.forName(packageName      + "."      + file.getName().substring(0,        file.getName().length() - 6)));   }  }  return classes; } public static void main(String[] args) {  try {   List<Class> list=getClassesByPackageName("com.test");   for (int i = 0; i < list.size(); i++) {    System.out.println(list.get(i).getName());   }  } catch (IOException e) {   // TODO Auto-generated catch block   e.printStackTrace();  } catch (ClassNotFoundException e) {   // TODO Auto-generated catch block   e.printStackTrace();  } }

///2016.3.15以下是我调试通过：

package test;import java.io.File;import java.io.IOException;import java.net.URL;import java.util.ArrayList;import java.util.Enumeration;public class TestClass{public static void main(String[] args) {  try {  ArrayList<Class> list=getClassesByPackageName("test");   for (int i = 0; i < list.size(); i++) {    System.out.println(list.get(i).getName());   }  } catch (IOException e) {   // TODO Auto-generated catch block   e.printStackTrace();  } catch (ClassNotFoundException e) {   // TODO Auto-generated catch block   e.printStackTrace();  }}private static ArrayList<Class> getClassesByPackageName(String packageName)throws IOException, ClassNotFoundException {  ClassLoader classLoader = Thread.currentThread()    .getContextClassLoader();  String path = packageName.replace('.', '/');  Enumeration<URL> resources = classLoader.getResources(path);  ArrayList<File> dirs = new ArrayList<File>();  while (resources.hasMoreElements()) {   URL resource = resources.nextElement();   dirs.add(new File(resource.getFile()));  }  ArrayList<Class> classes = new ArrayList<Class>();  for (File directory : dirs) {   classes.addAll(findClasses(directory, packageName));  }  return classes;}private static ArrayList<Class> findClasses(File directory, String packageName)throws ClassNotFoundException {  ArrayList<Class> classes = new ArrayList<Class>();  if (!directory.exists())   {  return classes;  }  File[] files = directory.listFiles();  for (File file : files)   {   if (file.isDirectory())    {    // 递归查找文件夹【即对应的包】下面的所有文件    assert !file.getName().contains(".");    classes.addAll(findClasses(file, packageName + '.'      + file.getName()));   }    else if (file.getName().endsWith(".class"))    {    classes.add(Class.forName(packageName      + "."      + file.getName().substring(0,        file.getName().length() - 6)));   }  }  return classes;}}

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