Java ModuleReference类代码示例

import java.lang.module.ModuleReference; //导入依赖的package包/类
boolean isAutomaticModuleNameAttributeAvailable(ModuleReference moduleReference) {
  try (var moduleReader = moduleReference.open()) {
    var manifestString =
        moduleReader
            .read("META-INF/MANIFEST.MF")
            .map(StandardCharsets.UTF_8::decode)
            .map(Object::toString)
            .orElse("");
    if (manifestString.contains("Automatic-Module-Name")) {
      return true;
    }
  } catch (Exception e) {
    debug("reading manifest failed: {0}", e);
  }
  return false;
}
 

import java.lang.module.ModuleReference; //导入依赖的package包/类
void add(ModuleDescriptor... descriptors) {
    for (ModuleDescriptor descriptor: descriptors) {
        String name = descriptor.name();
        if (!namesToReference.containsKey(name)) {
            //modules.add(descriptor);

            URI uri = URI.create("module:/" + descriptor.name());

            ModuleReference mref = new ModuleReference(descriptor, uri) {
                @Override
                public ModuleReader open() {
                    throw new UnsupportedOperationException();
                }
            };

            namesToReference.put(name, mref);
        }
    }
}
 

import java.lang.module.ModuleReference; //导入依赖的package包/类
private static Set<String> javaSE() {
    String root = "java.se.ee";
    ModuleFinder system = ModuleFinder.ofSystem();
    if (system.find(root).isPresent()) {
        return Stream.concat(Stream.of(root),
                             Configuration.empty().resolve(system,
                                                           ModuleFinder.of(),
                                                           Set.of(root))
                                          .findModule(root).get()
                                          .reads().stream()
                                          .map(ResolvedModule::name))
                     .collect(toSet());
    } else {
        // approximation
        return system.findAll().stream()
            .map(ModuleReference::descriptor)
            .map(ModuleDescriptor::name)
            .filter(name -> name.startsWith("java.") &&
                                !name.equals("java.smartcardio"))
            .collect(Collectors.toSet());
    }
}
 

import java.lang.module.ModuleReference; //导入依赖的package包/类
public Module toModule(ModuleReference mref) {
    try {
        String mn = mref.descriptor().name();
        URI location = mref.location().orElseThrow(FileNotFoundException::new);
        ModuleDescriptor md = mref.descriptor();
        Module.Builder builder = new Module.Builder(md, system.find(mn).isPresent());

        final ClassFileReader reader;
        if (location.getScheme().equals("jrt")) {
            reader = system.getClassReader(mn);
        } else {
            reader = ClassFileReader.newInstance(Paths.get(location), version);
        }

        builder.classes(reader);
        builder.location(location);

        return builder.build();
    } catch (IOException e) {
        throw new UncheckedIOException(e);
    }
}
 

import java.lang.module.ModuleReference; //导入依赖的package包/类
public static void main(String[] args) throws IOException {

        if (args.length != 1) {
            System.err.println("Usage AddPackagesAttribute exploded-java-home");
            System.exit(-1);
        }

        String home = args[0];
        Path dir = Paths.get(home, "modules");

        ModuleFinder finder = ModuleFinder.of(dir);

        try (DirectoryStream<Path> stream = Files.newDirectoryStream(dir)) {
            for (Path entry : stream) {
                Path mi = entry.resolve("module-info.class");
                if (Files.isRegularFile(mi)) {
                    String mn = entry.getFileName().toString();
                    Optional<ModuleReference> omref = finder.find(mn);
                    if (omref.isPresent()) {
                        Set<String> packages = omref.get().descriptor().packages();
                        addPackagesAttribute(mi, packages);
                    }
                }
            }
        }
    }
 

import java.lang.module.ModuleReference; //导入依赖的package包/类
/**
 * Test that a JAR file with a Main-Class attribute that is not in the module
 */
public void testMissingMainClassPackage() throws IOException {
    Manifest man = new Manifest();
    Attributes attrs = man.getMainAttributes();
    attrs.put(Attributes.Name.MANIFEST_VERSION, "1.0.0");
    attrs.put(Attributes.Name.MAIN_CLASS, "p.Main");

    Path dir = Files.createTempDirectory(USER_DIR, "mods");
    createDummyJarFile(dir.resolve("m.jar"), man);

    // Main-Class should be ignored because package p is not in module
    Optional<ModuleReference> omref = ModuleFinder.of(dir).find("m");
    assertTrue(omref.isPresent());
    ModuleDescriptor descriptor = omref.get().descriptor();
    assertFalse(descriptor.mainClass().isPresent());
}
 

import java.lang.module.ModuleReference; //导入依赖的package包/类
/**
 * Creates a {@code Loader} in a loader pool that loads classes/resources
 * from one module.
 */
public Loader(ResolvedModule resolvedModule,
              LoaderPool pool,
              ClassLoader parent)
{
    super("Loader-" + resolvedModule.name(), parent);

    this.pool = pool;
    this.parent = parent;

    ModuleReference mref = resolvedModule.reference();
    ModuleDescriptor descriptor = mref.descriptor();
    String mn = descriptor.name();
    this.nameToModule = Map.of(mn, mref);

    Map<String, LoadedModule> localPackageToModule = new HashMap<>();
    LoadedModule lm = new LoadedModule(mref);
    descriptor.packages().forEach(pn -> localPackageToModule.put(pn, lm));
    this.localPackageToModule = localPackageToModule;

    this.acc = AccessController.getContext();
}
 

import java.lang.module.ModuleReference; //导入依赖的package包/类
/**
 * Register a module this class loader. This has the effect of making the
 * types in the module visible.
 */
public void loadModule(ModuleReference mref) {
    String mn = mref.descriptor().name();
    if (nameToModule.putIfAbsent(mn, mref) != null) {
        throw new InternalError(mn + " already defined to this loader");
    }

    LoadedModule loadedModule = new LoadedModule(this, mref);
    for (String pn : mref.descriptor().packages()) {
        LoadedModule other = packageToModule.putIfAbsent(pn, loadedModule);
        if (other != null) {
            throw new InternalError(pn + " in modules " + mn + " and "
                                    + other.mref().descriptor().name());
        }
    }

    // clear resources cache if VM is already initialized
    if (VM.isModuleSystemInited() && resourceCache != null) {
        resourceCache = null;
    }
}
 

import java.lang.module.ModuleReference; //导入依赖的package包/类
/**
 * Returns a URL to a resource of the given name in a module defined to
 * this class loader.
 */
@Override
public URL findResource(String mn, String name) throws IOException {
    URL url = null;

    if (mn != null) {
        // find in module
        ModuleReference mref = nameToModule.get(mn);
        if (mref != null) {
            url = findResource(mref, name);
        }
    } else {
        // find on class path
        url = findResourceOnClassPath(name);
    }

    return checkURL(url);  // check access before returning
}
 

import java.lang.module.ModuleReference; //导入依赖的package包/类
/**
 * Returns an input stream to a resource of the given name in a module
 * defined to this class loader.
 */
public InputStream findResourceAsStream(String mn, String name)
    throws IOException
{
    // Need URL to resource when running with a security manager so that
    // the right permission check is done.
    if (System.getSecurityManager() != null || mn == null) {
        URL url = findResource(mn, name);
        return (url != null) ? url.openStream() : null;
    }

    // find in module defined to this loader, no security manager
    ModuleReference mref = nameToModule.get(mn);
    if (mref != null) {
        return moduleReaderFor(mref).open(name).orElse(null);
    } else {
        return null;
    }
}
 

import java.lang.module.ModuleReference; //导入依赖的package包/类
/**
 * Returns the ModuleReader for the given module, creating it if needed
 */
private ModuleReader moduleReaderFor(ModuleReference mref) {
    ModuleReader reader = moduleToReader.get(mref);
    if (reader == null) {
        // avoid method reference during startup
        Function<ModuleReference, ModuleReader> create = new Function<>() {
            public ModuleReader apply(ModuleReference moduleReference) {
                try {
                    return mref.open();
                } catch (IOException e) {
                    // Return a null module reader to avoid a future class
                    // load attempting to open the module again.
                    return new NullModuleReader();
                }
            }
        };
        reader = moduleToReader.computeIfAbsent(mref, create);
    }
    return reader;
}
 

import java.lang.module.ModuleReference; //导入依赖的package包/类
/**
 * Creates a ModuleReference to a possibly-patched module
 */
private static ModuleReference newModule(ModuleInfo.Attributes attrs,
                                         URI uri,
                                         Supplier<ModuleReader> supplier,
                                         ModulePatcher patcher,
                                         HashSupplier hasher) {
    ModuleReference mref = new ModuleReferenceImpl(attrs.descriptor(),
                                                   uri,
                                                   supplier,
                                                   null,
                                                   attrs.target(),
                                                   attrs.recordedHashes(),
                                                   hasher,
                                                   attrs.moduleResolution());
    if (patcher != null)
        mref = patcher.patchIfNeeded(mref);

    return mref;
}
 

import java.lang.module.ModuleReference; //导入依赖的package包/类
/**
 * Checks incubating status of modules in the configuration
 */
private static void checkIncubatingStatus(Configuration cf) {
    String incubating = null;
    for (ResolvedModule resolvedModule : cf.modules()) {
        ModuleReference mref = resolvedModule.reference();

        // emit warning if the WARN_INCUBATING module resolution bit set
        if (ModuleResolution.hasIncubatingWarning(mref)) {
            String mn = mref.descriptor().name();
            if (incubating == null) {
                incubating = mn;
            } else {
                incubating += ", " + mn;
            }
        }
    }
    if (incubating != null)
        warn("Using incubator modules: " + incubating);
}
 

import java.lang.module.ModuleReference; //导入依赖的package包/类
@Override
public Optional<ModuleReference> find(String name) {
    Objects.requireNonNull(name);

    // try cached modules
    ModuleReference m = cachedModules.get(name);
    if (m != null)
        return Optional.of(m);

    // the module may not have been encountered yet
    while (hasNextEntry()) {
        scanNextEntry();
        m = cachedModules.get(name);
        if (m != null)
            return Optional.of(m);
    }
    return Optional.empty();
}
 

import java.lang.module.ModuleReference; //导入依赖的package包/类
/**
 * Scans the next entry on the module path. A no-op if all entries have
 * already been scanned.
 *
 * @throws FindException if an error occurs scanning the next entry
 */
private void scanNextEntry() {
    if (hasNextEntry()) {

        long t0 = System.nanoTime();

        Path entry = entries[next];
        Map<String, ModuleReference> modules = scan(entry);
        next++;

        // update cache, ignoring duplicates
        int initialSize = cachedModules.size();
        for (Map.Entry<String, ModuleReference> e : modules.entrySet()) {
            cachedModules.putIfAbsent(e.getKey(), e.getValue());
        }

        // update counters
        int added = cachedModules.size() - initialSize;
        moduleCount.add(added);

        scanTime.addElapsedTimeFrom(t0);
    }
}