Java Plugin类代码示例

import org.apache.logging.log4j.core.config.plugins.Plugin; //导入依赖的package包/类
@Override
public boolean process(final Set<? extends TypeElement> annotations, final RoundEnvironment roundEnv) {
    System.out.println("Processing annotations");
    try {
        final Set<? extends Element> elements = roundEnv.getElementsAnnotatedWith(Plugin.class);
        if (elements.isEmpty()) {
            System.out.println("No elements to process");
            return false;
        }
        collectPlugins(elements);
        writeCacheFile(elements.toArray(new Element[elements.size()]));
        System.out.println("Annotations processed");
        return true;
    } catch (final IOException e) {
        e.printStackTrace();
        error(e.getMessage());
        return false;
    } catch (final Exception ex) {
        ex.printStackTrace();
        error(ex.getMessage());
        return false;
    }
}
 

import org.apache.logging.log4j.core.config.plugins.Plugin; //导入依赖的package包/类
private void collectPlugins(final Iterable<? extends Element> elements) {
    final Elements elementUtils = processingEnv.getElementUtils();
    final ElementVisitor<PluginEntry, Plugin> pluginVisitor = new PluginElementVisitor(elementUtils);
    final ElementVisitor<Collection<PluginEntry>, Plugin> pluginAliasesVisitor = new PluginAliasesElementVisitor(
            elementUtils);
    for (final Element element : elements) {
        final Plugin plugin = element.getAnnotation(Plugin.class);
        if (plugin == null) {
            continue;
        }
        final PluginEntry entry = element.accept(pluginVisitor, plugin);
        final Map<String, PluginEntry> category = pluginCache.getCategory(entry.getCategory());
        category.put(entry.getKey(), entry);
        final Collection<PluginEntry> entries = element.accept(pluginAliasesVisitor, plugin);
        for (final PluginEntry pluginEntry : entries) {
            category.put(pluginEntry.getKey(), pluginEntry);
        }
    }
}
 

import org.apache.logging.log4j.core.config.plugins.Plugin; //导入依赖的package包/类
@Override
public Collection<PluginEntry> visitType(final TypeElement e, final Plugin plugin) {
    final PluginAliases aliases = e.getAnnotation(PluginAliases.class);
    if (aliases == null) {
        return DEFAULT_VALUE;
    }
    final Collection<PluginEntry> entries = new ArrayList<>(aliases.value().length);
    for (final String alias : aliases.value()) {
        final PluginEntry entry = new PluginEntry();
        entry.setKey(alias.toLowerCase(Locale.US));
        entry.setClassName(elements.getBinaryName(e).toString());
        entry.setName(Plugin.EMPTY.equals(plugin.elementType()) ? alias : plugin.elementType());
        entry.setPrintable(plugin.printObject());
        entry.setDefer(plugin.deferChildren());
        entry.setCategory(plugin.category());
        entries.add(entry);
    }
    return entries;
}
 

import org.apache.logging.log4j.core.config.plugins.Plugin; //导入依赖的package包/类
private void verifyFakePluginEntry(final String name, final PluginEntry fake) {
    assertNotNull("The plugin '" + name.toLowerCase() + "' was not found.", fake);
    assertEquals(FakePlugin.class.getName(), fake.getClassName());
    assertEquals(name.toLowerCase(), fake.getKey());
    assertEquals(Plugin.EMPTY, p.elementType());
    assertEquals(name, fake.getName());
    assertEquals(p.printObject(), fake.isPrintable());
    assertEquals(p.deferChildren(), fake.isDefer());
}
 

import org.apache.logging.log4j.core.config.plugins.Plugin; //导入依赖的package包/类
@Test
public void testNestedPlugin() throws Exception {
    final Plugin p = FakePlugin.Nested.class.getAnnotation(Plugin.class);
    final PluginEntry nested = pluginCache.getCategory(p.category()).get(p.name().toLowerCase());
    assertNotNull(nested);
    assertEquals(p.name().toLowerCase(), nested.getKey());
    assertEquals(FakePlugin.Nested.class.getName(), nested.getClassName());
    assertEquals(p.name(), nested.getName());
    assertEquals(Plugin.EMPTY, p.elementType());
    assertEquals(p.printObject(), nested.isPrintable());
    assertEquals(p.deferChildren(), nested.isDefer());
}
 

import org.apache.logging.log4j.core.config.plugins.Plugin; //导入依赖的package包/类
/**
 * @since 2.1
 */
public Map<String, List<PluginType<?>>> loadFromPackage(final String pkg) {
    if (Strings.isBlank(pkg)) {
        // happens when splitting an empty string
        return Collections.emptyMap();
    }
    Map<String, List<PluginType<?>>> existing = pluginsByCategoryByPackage.get(pkg);
    if (existing != null) {
        // already loaded this package
        return existing;
    }

    final long startTime = System.nanoTime();
    final ResolverUtil resolver = new ResolverUtil();
    final ClassLoader classLoader = Loader.getClassLoader();
    if (classLoader != null) {
        resolver.setClassLoader(classLoader);
    }
    resolver.findInPackage(new PluginTest(), pkg);

    final Map<String, List<PluginType<?>>> newPluginsByCategory = new HashMap<>();
    for (final Class<?> clazz : resolver.getClasses()) {
        final Plugin plugin = clazz.getAnnotation(Plugin.class);
        final String categoryLowerCase = plugin.category().toLowerCase();
        List<PluginType<?>> list = newPluginsByCategory.get(categoryLowerCase);
        if (list == null) {
            newPluginsByCategory.put(categoryLowerCase, list = new ArrayList<>());
        }
        final PluginEntry mainEntry = new PluginEntry();
        final String mainElementName = plugin.elementType().equals(
            Plugin.EMPTY) ? plugin.name() : plugin.elementType();
        mainEntry.setKey(plugin.name().toLowerCase());
        mainEntry.setName(plugin.name());
        mainEntry.setCategory(plugin.category());
        mainEntry.setClassName(clazz.getName());
        mainEntry.setPrintable(plugin.printObject());
        mainEntry.setDefer(plugin.deferChildren());
        final PluginType<?> mainType = new PluginType<>(mainEntry, clazz, mainElementName);
        list.add(mainType);
        final PluginAliases pluginAliases = clazz.getAnnotation(PluginAliases.class);
        if (pluginAliases != null) {
            for (final String alias : pluginAliases.value()) {
                final PluginEntry aliasEntry = new PluginEntry();
                final String aliasElementName = plugin.elementType().equals(
                    Plugin.EMPTY) ? alias.trim() : plugin.elementType();
                aliasEntry.setKey(alias.trim().toLowerCase());
                aliasEntry.setName(plugin.name());
                aliasEntry.setCategory(plugin.category());
                aliasEntry.setClassName(clazz.getName());
                aliasEntry.setPrintable(plugin.printObject());
                aliasEntry.setDefer(plugin.deferChildren());
                final PluginType<?> aliasType = new PluginType<>(aliasEntry, clazz, aliasElementName);
                list.add(aliasType);
            }
        }
    }

    final long endTime = System.nanoTime();
    final DecimalFormat numFormat = new DecimalFormat("#0.000000");
    final double seconds = (endTime - startTime) * 1e-9;
    LOGGER.debug("Took {} seconds to load {} plugins from package {}",
        numFormat.format(seconds), resolver.getClasses().size(), pkg);

    // Note multiple threads could be calling this method concurrently. Both will do the work,
    // but only one will be allowed to store the result in the outer map.
    // Return the inner map produced by whichever thread won the race, so all callers will get the same result.
    existing = pluginsByCategoryByPackage.putIfAbsent(pkg, newPluginsByCategory);
    if (existing != null) {
        return existing;
    }
    return newPluginsByCategory;
}
 

import org.apache.logging.log4j.core.config.plugins.Plugin; //导入依赖的package包/类
@Override
public boolean matches(final Class<?> type) {
    return type != null && type.isAnnotationPresent(Plugin.class);
}
 

import org.apache.logging.log4j.core.config.plugins.Plugin; //导入依赖的package包/类
@Override
public String toString() {
    return "annotated with @" + Plugin.class.getSimpleName();
}
 

import org.apache.logging.log4j.core.config.plugins.Plugin; //导入依赖的package包/类
/**
 * Tests the presence of certain annotations and converter key in a given Converter class
 *
 * @param clazz PatterConverter class to test
 * @param key Converter key to match
 */
private void testPatternAnnotation(Class<? extends AccessLogPatternConverter> clazz, String key) {
    assertTrue(clazz.isAnnotationPresent(Plugin.class));
    assertTrue(clazz.isAnnotationPresent(ConverterKeys.class));
    assertEquals(key, clazz.getAnnotation(ConverterKeys.class).value()[0]);
}