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[英]UnmarshalException and ClassNotFoundException: what am I doing wrong?
[英]URLClassLoader keeps throwing ClassNotFoundException. What am I doing wrong?
我正在一個大學的Java項目中工作,該項目要求我實現一個簡單的插件體系結構。 項目A中的一個主要應用程序必須從另一個項目B中的指定目錄中加載插件。在對該主題進行了一些研究(包括stackoverflow)之后,我決定使用URLClassLoader來加載我可能隨后會實例化的類。 項目B引用了項目A,並且所有插件都擴展了一個通用的插件類(也可以是一個接口,但不應有任何區別)。 到目前為止,這是我得到的:
我嘗試加載的插件類的源代碼:
package plugin;
import de.uks.student.pluginpattern.model.EditorPlugin;
public class Circle extends EditorPlugin
{
@Override
public void init()
{
}
}
以及應該加載該類的代碼:
public void init(String[] args)
{
editorPane = new EditorPane().withWidth(500).withHeight(500);
toolBar = new ToolBar();
plugins = new EditorPluginSet();
// load plugins
File pluginDir = new File(PLUGIN_PATH);
if (!pluginDir.exists())
{
System.err.println("Plugin path not found!!");
return;
}
String[] plugins = pluginDir.list();
if (plugins == null)
{
System.err.println("Plugin path points to a file!!");
return;
}
for (String pluginString : plugins)
{
for (String argString : args)
{
if (pluginString.contains(argString))
{
System.out.println("Loading plugin from " + pluginString);
File pluginFile = new File(PLUGIN_PATH + "/");
// as getAbsolutePath embeds the relative path ... /../pluginProject ...
// which may not be processed correctly by the OS (Windows at least),
// we correct the path manually (just to be on the safe side)
String absolutePath = pluginFile.getAbsolutePath();
String[] split = absolutePath.split("\\\\");
List<String> splitsimpleList = Arrays.asList(split);
ArrayList<String> splitList = new ArrayList<>(splitsimpleList);
for (int i = 0; i < splitList.size() - 1; ++i)
{
if (splitList.get(i + 1).equals(".."))
{
splitList.remove(i);
splitList.remove(i);
break;
}
}
StringBuilder b = new StringBuilder();
for (String string : splitList)
{
b.append(string);
b.append("/");
}
File pluginFileForRealThisTime = new File(b.toString());
URL pluginURL = null;
try
{
pluginURL = pluginFileForRealThisTime.toURI().toURL();
} catch (MalformedURLException e)
{
// TODO Auto-generated catch block
e.printStackTrace();
}
URL[] urls = {pluginURL};
ClassLoader parentClassLoader = this.getClass().getClassLoader();
URLClassLoader uLoader = new URLClassLoader(urls, parentClassLoader);
Class<?> pluginClass = null;
try
{
String className = "plugin." + argString;
pluginClass = uLoader.loadClass(className);
} catch (ClassNotFoundException e)
{
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
}
}
現在,我總是以ClassNotFoundException結尾:
java.lang.ClassNotFoundException:plugin.Circle在java.net.URLClassLoader $ 1.run(未知源)在java.net.URLClassLoader $ 1.run(在java.security.AccessController.doPrivileged(本機方法)處)。 net.URLClassLoader.findClass(未知源)在java.lang.ClassLoader.loadClass(未知源)在java.lang.ClassLoader.loadClass(未知源)在de.uks.student.pluginpattern.model.EditorSystem.init(EditorSystem。 java:412),位於de.uks.student.pluginpattern.EditorSystem.main(EditorSystem.java:13)
我已經檢查過了
我幾乎沒有其他嘗試方法的想法。 我究竟做錯了什么?
我必須將ClassLoader指向bin文件夾而不是bin / plugins文件夾
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