如何获取包中的所有类?
user89473
问问题
5534 次
6 回答
10
你不能。类可以通过许多不同的类加载器进入,包括远程加载器。
于 2009-07-20T23:40:28.753 回答
7
根据 JG 发布的想法,这是解决罐子问题的更完整方法。
/**
* Scans all classloaders for the current thread for loaded jars, and then scans
* each jar for the package name in question, listing all classes directly under
* the package name in question. Assumes directory structure in jar file and class
* package naming follow java conventions (i.e. com.example.test.MyTest would be in
* /com/example/test/MyTest.class)
*/
public Collection<Class> getClassesForPackage(String packageName) throws Exception {
String packagePath = packageName.replace(".", "/");
ClassLoader classLoader = Thread.currentThread().getContextClassLoader();
Set<URL> jarUrls = new HashSet<URL>();
while (classLoader != null) {
if (classLoader instanceof URLClassLoader)
for (URL url : ((URLClassLoader) classLoader).getURLs())
if (url.getFile().endsWith(".jar") // may want better way to detect jar files
jarUrls.add(url);
classLoader = classLoader.getParent();
}
Set<Class> classes = new HashSet<Class>();
for (URL url : jarUrls) {
JarInputStream stream = new JarInputStream(url.openStream()); // may want better way to open url connections
JarEntry entry = stream.getNextJarEntry();
while (entry != null) {
String name = entry.getName();
int i = name.lastIndexOf("/");
if (i > 0 && name.endsWith(".class") && name.substring(0, i).equals(packagePath))
classes.add(Class.forName(name.substring(0, name.length() - 6).replace("/", ".")));
entry = stream.getNextJarEntry();
}
stream.close();
}
return classes;
}
于 2009-07-21T04:46:07.987 回答
4
假设可以在本地找到类,这里有一个片段可以完全满足您的要求:
private static Class[] getClasses(String packageName)
throws ClassNotFoundException, IOException {
ClassLoader classLoader = Thread.currentThread().getContextClassLoader();
assert classLoader != null;
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.toArray(new Class[classes.size()]);
}
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()) {
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;
}
于 2009-07-20T23:46:33.780 回答
1
没有全球性的方法可以做到这一点。话虽如此,如果你知道你的类来自哪里,你可以遍历 jar 文件或文件系统的目录。
于 2009-07-20T23:44:56.687 回答
1
Java 没有发现功能。
大多数能够添加(发现)新类的产品要么有一个描述“程序扩展”的文本文件,要么有一个特定的目录,您可以在其中放置使用@JG 描述的技巧的类或 jar。(这是 eclipse 所做的,并且推荐用于用户可以手动添加新模块的任何解决方案)
于 2009-07-20T23:56:23.013 回答