嘗試使用 PF4J 時，我創(chuàng)建了必要的部分，如https://github.com/pf4j/pf4j擴展 ExtensionPoint 的接口一個插件帶有清單的罐子插件加載和激活為什么 clickHandlers 列表是空的？我已經(jīng)使用 JUnit 測試對此進(jìn)行了測試，我可以在其中調(diào)試似乎工作正常的其他部分。請參閱下面的調(diào)試日志。我還查看了https://github.com/pf4j/pf4j/issues/21并激活了 Eclipse 注釋處理，但沒有任何積極影響。1.擴展擴展點的接口public interface ClickHandler extends ExtensionPoint {...}2.一個插件public class MBClickHandlerPlugin extends Plugin { /** * construct me * @param wrapper */ public MBClickHandlerPlugin(PluginWrapper wrapper) { super(wrapper); } @Extension public static class MBClickHandler implements ClickHandler { }}3. 帶有清單的罐子unzip -q -c target/com.bitplan.mb-0.0.1.jar META-INF/MANIFEST.MFManifest-Version: 1.0Plugin-Dependencies: Plugin-Id: com.bitplan.mbBuilt-By: wfPlugin-Provider: BITPlan GmbHPlugin-Version: 0.0.1Plugin-Class: com.bitplan.mb.MBClickHandlerPluginCreated-By: Apache Maven 3.5.2Build-Jdk: 1.8.0_1524.插件加載和激活 /** * activate the plugins requested on the command line */ public void activatePlugins() { pluginManager = new DefaultPluginManager(); for (String plugin : plugins) { Path pluginPath = Paths.get(plugin); pluginManager.loadPlugin(pluginPath); } pluginManager.startPlugins(); List<ClickHandler> clickHandlers = pluginManager .getExtensions(ClickHandler.class); for (ClickHandler clickHandler : clickHandlers) { installClickHandler(clickHandler); } }
1 回答
慕的地6264312
TA貢獻(xiàn)1817條經(jīng)驗 獲得超6個贊
解決方法 #1
使用定制的 PluginManager
pluginManager = new JarPluginManager(this.getClass().getClassLoader());
從將使用插件的類中確保使用相同的類加載器
JarPluginManager 源代碼：
import java.nio.file.Path;
import org.pf4j.DefaultPluginManager;
import org.pf4j.JarPluginLoader;
import org.pf4j.ManifestPluginDescriptorFinder;
import org.pf4j.PluginClassLoader;
import org.pf4j.PluginDescriptor;
import org.pf4j.PluginDescriptorFinder;
import org.pf4j.PluginLoader;
import org.pf4j.PluginManager;
/**
* see https://github.com/pf4j/pf4j/issues/249 see
* https://pf4j.org/doc/class-loading.html
*
* @author wf
*
*/
public class JarPluginManager extends DefaultPluginManager {
public static class ParentClassLoaderJarPluginLoader extends JarPluginLoader {
static ClassLoader parentClassLoader;
/**
*
* @param pluginManager
*/
public ParentClassLoaderJarPluginLoader(PluginManager pluginManager) {
super(pluginManager);
}
static PluginClassLoader pluginClassLoader;
@Override
public ClassLoader loadPlugin(Path pluginPath,
PluginDescriptor pluginDescriptor) {
if (pluginClassLoader == null) {
boolean parentFirst=true;
pluginClassLoader = new PluginClassLoader(pluginManager,
pluginDescriptor, parentClassLoader,parentFirst);
}
pluginClassLoader.addFile(pluginPath.toFile());
return pluginClassLoader;
}
}
/**
* construct me with the given classloader
* @param classLoader
*/
public JarPluginManager(ClassLoader classLoader) {
ParentClassLoaderJarPluginLoader.parentClassLoader=classLoader;
//System.setProperty("pf4j.mode", RuntimeMode.DEPLOYMENT.toString());
//System.setProperty("pf4j.mode", RuntimeMode.DEVELOPMENT.toString());
}
@Override
protected PluginLoader createPluginLoader() {
// load only jar plugins
return new ParentClassLoaderJarPluginLoader(this);
}
@Override
protected PluginDescriptorFinder createPluginDescriptorFinder() {
// read plugin descriptor from jar's manifest
return new ManifestPluginDescriptorFinder();
}
}
解決方法 #2 如果未創(chuàng)建 extensions.idx 文件，則說明您的注釋處理有問題。您可能想解決問題的根源，但也可以嘗試解決它：
https://groups.google.com/forum/#!topic/pf4j/nn20axJHpfI 指出我手動創(chuàng)建 META-INF/extensions.idx 文件并確保靜態(tài)內(nèi)部類沒有 args 構(gòu)造函數(shù)。有了這個改變，事情就開始了。
注意在 extensions.idx 文件中正確設(shè)置類名 - 否則您將在處理程序列表中得到一個空條目
注意有一個空參數(shù)構(gòu)造函數(shù)，否則你會得到一個異常
@Extension
public static class MBClickHandler implements ClickHandler {
/**
* constructor with no argument
*/
public MBClickHandler() {
}
src/main/resources/META-INF/extensions.idx
com.bitplan.mb.MBClickHandlerPlugin$MBClickHandler
要檢查的代碼
extension.idx 條目的正確名稱
MBClickHandler ch=new MBClickHandler();
File extFile=new File("src/main/resources/META-INF/extensions.idx");
String extidx=FileUtils.readFileToString(extFile,"UTF-8");
assertEquals(extidx,ch.getClass().getName());
檢查擴展
List<PluginWrapper> startedPlugins = pluginManager.getStartedPlugins();
for (PluginWrapper plugin : startedPlugins) {
String pluginId = plugin.getDescriptor().getPluginId();
System.out.println(String.format("Extensions added by plugin '%s':", pluginId));
Set<String> extensionClassNames = pluginManager.getExtensionClassNames(pluginId);
for (String extension : extensionClassNames) {
System.out.println(" " + extension);
}
}
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