在Eclipse插件中使用时,Reflections库无法正常工作

Question

我使用Reflections库开发了一个应用程序,用于查询具有特定注释的所有类.在我决定从我的应用程序创建一个Eclipse插件之前,一切都像魅力一样.然后,思考停止工作.

鉴于我的应用程序在不是Eclipse插件的一部分时工作正常,我认为它应该是一个类加载器问题.所以我在我Reflections的类中添加了插件激活器类的类加载器,上下文类加载器以及我能想象的所有其他类加载器,没有任何成功.这是我的代码的简化版本:

ConfigurationBuilder config = new ConfigurationBuilder();
config.addClassLoaders(thePluginActivatorClassLoader);
config.addClassLoaders(ClasspathHelper.getContextClassLoader());
config.addClassLoaders("all the classloaders I could imagine");
config.filterInputsBy(new FilterBuilder().include("package I want to analyze"));

Reflections reflections = new Reflections(config);
Set<Class<?>> classes = reflections.getTypesAnnotatedWith(MyAnnotation.class); //this Set is empty

我也尝试添加我想要加载到ConfigurationBuilder类的类的URL ,但它没有帮助.

有人能告诉我是否有办法让Reflections工作成为Eclipse插件的一部分？或者我应该更好地寻找另一种替代方案？非常感谢,我真的很困惑.

Answer 1

我假设您已经知道如何创建包(否则,请检查此).

在对Reflections API进行了一些调查和探索之后,我意识到问题是Reflection只是无法读取OSGi URL(bundleresource:// ...)导致异常:

org.reflections.ReflectionsException: could not create Vfs.Dir from url, 
no matching UrlType was found [bundleresource://1009.fwk651584550/]

这个建议:

either use fromURL(final URL url, final List<UrlType> urlTypes) 
or use the static setDefaultURLTypes(final List<UrlType> urlTypes) 
or addDefaultURLTypes(UrlType urlType) with your specialized UrlType.

所以我相信为OSGi实现一个UrlType(例如class BundleUrlType implements UrlType {...})并像这样注册它:

Vfs.addDefaultURLTypes(new BundleUrlType());

应该使束内的Reflections API可用.描述思考的依赖应该被添加到Eclipse插件项目在这里.

这是添加所需罐子后我的样品MANIFEST.MF的样子:

Manifest-Version: 1.0
Bundle-ManifestVersion: 2
Bundle-Name: ReflectivePlugin
Bundle-SymbolicName: ReflectivePlugin
Bundle-Version: 1.0.0.qualifier
Bundle-Activator: reflectiveplugin.Activator
Bundle-ActivationPolicy: lazy
Bundle-RequiredExecutionEnvironment: JavaSE-1.6
Import-Package: javax.annotation;version="1.0.0",
 org.osgi.framework;version="1.3.0",
 org.osgi.service.log;version="1.3",
 org.osgi.util.tracker;version="1.3.1"
Bundle-ClassPath: .,
 lib/dom4j-1.6.1.jar,
 lib/guava-r08.jar,
 lib/javassist-3.12.1.GA.jar,
 lib/reflections-0.9.5.jar,
 lib/slf4j-api-1.6.1.jar,
 lib/xml-apis-1.0.b2.jar
Export-Package: reflectiveplugin, 
 reflectiveplugin.data

注意:使用Reflections v.9.5.5

以下是UrlType实现的示例:

package reflectiveplugin;

import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import java.util.Enumeration;
import java.util.Iterator;

import org.osgi.framework.Bundle;
import org.reflections.vfs.Vfs;
import org.reflections.vfs.Vfs.Dir;
import org.reflections.vfs.Vfs.File;
import org.reflections.vfs.Vfs.UrlType;

import com.google.common.collect.AbstractIterator;

public class BundleUrlType implements UrlType {

    public static final String BUNDLE_PROTOCOL = "bundleresource";

    private final Bundle bundle;

    public BundleUrlType(Bundle bundle) {
        this.bundle = bundle;
    }

    @Override
    public boolean matches(URL url) {
        return BUNDLE_PROTOCOL.equals(url.getProtocol());
    }

    @Override
    public Dir createDir(URL url) {
        return new BundleDir(bundle, url);
    }

    public class BundleDir implements Dir {

        private String path;
        private final Bundle bundle;

        public BundleDir(Bundle bundle, URL url) {
            this(bundle, url.getPath());
        }

        public BundleDir(Bundle bundle, String p) {
            this.bundle = bundle;
            this.path = p;
            if (path.startsWith(BUNDLE_PROTOCOL + ":")) { 
                path = path.substring((BUNDLE_PROTOCOL + ":").length()); 
            }
        }

        @Override
        public String getPath() {
            return path;
        }

        @Override
        public Iterable<File> getFiles() {
            return new Iterable<Vfs.File>() {
                public Iterator<Vfs.File> iterator() {
                    return new AbstractIterator<Vfs.File>() {
                        final Enumeration<URL> entries = bundle.findEntries(path, "*.class", true);

                        protected Vfs.File computeNext() {
                            return entries.hasMoreElements() ? new BundleFile(BundleDir.this, entries.nextElement()) : endOfData();
                        }
                    };
                }
            };
        }

        @Override
        public void close() { }
    }

    public class BundleFile implements File {

        private final BundleDir dir;
        private final String name;
        private final URL url;

        public BundleFile(BundleDir dir, URL url) {
            this.dir = dir;
            this.url = url;
            String path = url.getFile();
            this.name = path.substring(path.lastIndexOf("/") + 1);
        }

        @Override
        public String getName() {
            return name;
        }

        @Override
        public String getRelativePath() {
            return getFullPath().substring(dir.getPath().length());
        }

        @Override
        public String getFullPath() {
            return url.getFile();
        }

        @Override
        public InputStream openInputStream() throws IOException {
            return url.openStream();
        }
    }
}

这就是我在Activator类中创建反射的方法:

private Reflections createReflections(Bundle bundle) {
    Vfs.addDefaultURLTypes(new BundleUrlType(bundle));
    Reflections reflections = new Reflections(new Object[] { "reflectiveplugin.data" });
    return reflections;
}

最后一点非常令人困惑,但仍然很重要:如果你在Eclipse(Run As/OSGi Framework)中运行你的插件,你必须将你的类输出目录添加到Reflections路径模式(即"bin"或"target/classes" ").虽然,发布的插件不需要它(构建插件/包做"导出" - >"可部署的插件和片段").