以下代码在Java 9+（Jigsaw / JPMS）中实现了模块路径扫描。它查找调用堆栈上的所有类，然后对于每个类引用，调用 ，返回 a ，而不仅仅是 。（ 允许您访问模块资源，而不能。给定每个模块的引用，可以调用该方法来获取模块的 。 为您提供了 一个 ，它允许您列出模块中的资源，使用 或 使用 或 打开资源。然后，在完成模块后关闭 。在我见过的任何地方都没有记录这一点。要弄清楚这一切是非常困难的。但这是代码，希望其他人能从中受益。classRef.getModule().getLayer().getConfiguration().modules()List<ResolvedModule>List<Module>ResolvedModuleModuleResolvedModule.reference()ModuleReferenceModuleReference#open()ModuleReaderModuleReader#list()Optional<InputStream> ModuleReader#open(resourcePath)Optional<ByteBuffer> ModuleReader#read(resourcePath)ModuleReader
请注意，即使在 JDK9+ 中，您仍然可以使用传统的类路径元素以及模块路径元素，因此对于完整的模块路径 + 类路径扫描，您可能应该使用适当的类路径扫描解决方案，例如 ClassGraph，它支持使用以下机制进行模块扫描（免责声明，我是作者）。您可以在此处找到以下代码的基于反射的版本。
另请注意，在 JDK 9 之后的几个 JDK 版本中，StackWalker 中存在一个必须解决的错误，有关详细信息，请参阅上面的基于反射的代码。
package main;
import java.lang.StackWalker;
import java.lang.StackWalker.Option;
import java.lang.StackWalker.StackFrame;
import java.lang.module.ModuleReader;
import java.lang.module.ModuleReference;
import java.lang.module.ResolvedModule;
import java.net.URI;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.util.AbstractMap.SimpleEntry;
import java.util.ArrayDeque;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Deque;
import java.util.HashSet;
import java.util.List;
import java.util.Map.Entry;
import java.util.Optional;
import java.util.Set;
import java.util.stream.Stream;
public class Java9Scanner {
/** Recursively find the topological sort order of ancestral layers. */
private static void findLayerOrder(ModuleLayer layer,
Set<ModuleLayer> visited, Deque<ModuleLayer> layersOut) {
if (visited.add(layer)) {
List<ModuleLayer> parents = layer.parents();
for (int i = 0; i < parents.size(); i++) {
findLayerOrder(parents.get(i), visited, layersOut);
}
layersOut.push(layer);
}
}
/** Get ModuleReferences from a Class reference. */
private static List<Entry<ModuleReference, ModuleLayer>> findModuleRefs(
Class<?>[] callStack) {
Deque<ModuleLayer> layerOrder = new ArrayDeque<>();
Set<ModuleLayer> visited = new HashSet<>();
for (int i = 0; i < callStack.length; i++) {
ModuleLayer layer = callStack[i].getModule().getLayer();
findLayerOrder(layer, visited, layerOrder);
}
Set<ModuleReference> addedModules = new HashSet<>();
List<Entry<ModuleReference, ModuleLayer>> moduleRefs = new ArrayList<>();
for (ModuleLayer layer : layerOrder) {
Set<ResolvedModule> modulesInLayerSet = layer.configuration()
.modules();
final List<Entry<ModuleReference, ModuleLayer>> modulesInLayer =
new ArrayList<>();
for (ResolvedModule module : modulesInLayerSet) {
modulesInLayer
.add(new SimpleEntry<>(module.reference(), layer));
}
// Sort modules in layer by name for consistency
Collections.sort(modulesInLayer,
(e1, e2) -> e1.getKey().descriptor().name()
.compareTo(e2.getKey().descriptor().name()));
// To be safe, dedup ModuleReferences, in case a module occurs in multiple
// layers and reuses its ModuleReference (no idea if this can happen)
for (Entry<ModuleReference, ModuleLayer> m : modulesInLayer) {
if (addedModules.add(m.getKey())) {
moduleRefs.add(m);
}
}
}
return moduleRefs;
}
/** Get the classes in the call stack. */
private static Class<?>[] getCallStack() {
// Try StackWalker (JDK 9+)
PrivilegedAction<Class<?>[]> stackWalkerAction =
(PrivilegedAction<Class<?>[]>) () ->
StackWalker.getInstance(
Option.RETAIN_CLASS_REFERENCE)
.walk(s -> s.map(
StackFrame::getDeclaringClass)
.toArray(Class[]::new));
try {
// Try with doPrivileged()
return AccessController
.doPrivileged(stackWalkerAction);
} catch (Exception e) {
}
try {
// Try without doPrivileged()
return stackWalkerAction.run();
} catch (Exception e) {
}
// Try SecurityManager
PrivilegedAction<Class<?>[]> callerResolverAction =
(PrivilegedAction<Class<?>[]>) () ->
new SecurityManager() {
@Override
public Class<?>[] getClassContext() {
return super.getClassContext();
}
}.getClassContext();
try {
// Try with doPrivileged()
return AccessController
.doPrivileged(callerResolverAction);
} catch (Exception e) {
}
try {
// Try without doPrivileged()
return callerResolverAction.run();
} catch (Exception e) {
}
// As a fallback, use getStackTrace() to try to get the call stack
try {
throw new Exception();
} catch (final Exception e) {
final List<Class<?>> classes = new ArrayList<>();
for (final StackTraceElement elt : e.getStackTrace()) {
try {
classes.add(Class.forName(elt.getClassName()));
} catch (final Throwable e2) {
// Ignore
}
}
if (classes.size() > 0) {
return classes.toArray(new Class<?>[0]);
} else {
// Last-ditch effort -- include just this class
return new Class<?>[] { Java9Scanner.class };
}
}
}
/**
* Return true if the given module name is a system module.
* There can be system modules in layers above the boot layer.
*/
private static boolean isSystemModule(
final ModuleReference moduleReference) {
String name = moduleReference.descriptor().name();
if (name == null) {
return false;
}
return name.startsWith("java.") || name.startsWith("jdk.")
|| name.startsWith("javafx.") || name.startsWith("oracle.");
}
public static void main(String[] args) throws Exception {
// Get ModuleReferences for modules of all classes in call stack,
List<Entry<ModuleReference, ModuleLayer>> systemModuleRefs = new ArrayList<>();
List<Entry<ModuleReference, ModuleLayer>> nonSystemModuleRefs = new ArrayList<>();
Class<?>[] callStack = getCallStack();
List<Entry<ModuleReference, ModuleLayer>> moduleRefs = findModuleRefs(
callStack);
// Split module refs into system and non-system modules based on module name
for (Entry<ModuleReference, ModuleLayer> m : moduleRefs) {
(isSystemModule(m.getKey()) ? systemModuleRefs
: nonSystemModuleRefs).add(m);
}
// List system modules
System.out.println("\nSYSTEM MODULES:\n");
for (Entry<ModuleReference, ModuleLayer> e : systemModuleRefs) {
ModuleReference ref = e.getKey();
System.out.println(" " + ref.descriptor().name());
}
// Show info for non-system modules
System.out.println("\nNON-SYSTEM MODULES:");
for (Entry<ModuleReference, ModuleLayer> e : nonSystemModuleRefs) {
ModuleReference ref = e.getKey();
ModuleLayer layer = e.getValue();
System.out.println("\n " + ref.descriptor().name());
System.out.println(
" Version: " + ref.descriptor().toNameAndVersion());
System.out.println(
" Packages: " + ref.descriptor().packages());
System.out.println(" ClassLoader: "
+ layer.findLoader(ref.descriptor().name()));
Optional<URI> location = ref.location();
if (location.isPresent()) {
System.out.println(" Location: " + location.get());
}
try (ModuleReader moduleReader = ref.open()) {
Stream<String> stream = moduleReader.list();
stream.forEach(s -> System.out.println(" File: " + s));
}
}
}
}
