java动态添加外部jar包到classpath的实例详解

String beanClassName = "com.dynamic.DynamicBean3"; 
Map<String,Class<?>> classMap = new HashMap<String,Class<?>>(); 
String filePath = "f:\\testDynamicBean-1.0-SNAPSHOT.jar"; 
String uFilePath = "file:f:\\testDynamicBean-1.0-SNAPSHOT.jar"; 
 
URL url1 = new URL(uFilePath); 
URLClassLoader urlClassLoader = new URLClassLoader(new URL[] { url1 }, Thread.currentThread() 
        .getContextClassLoader()); 
List<JarEntry> jarEntryList = new ArrayList<>(); 
JarFile jarFile = new JarFile(filePath); 
Enumeration<JarEntry> jarEntryEnumeration = jarFile.entries(); 
while (jarEntryEnumeration.hasMoreElements()){ 
   JarEntry jarEntry = jarEntryEnumeration.nextElement(); 
   if (//jarEntry.getName().startsWith(filePath) && 
      jarEntry.getName().endsWith(".class")) { 
        jarEntryList.add(jarEntry); 
      } 
    } 
 
   for (JarEntry entry : jarEntryList) { 
      String className = entry.getName().replace('/', '.'); 
      className = className.substring(0, className.length() - 6); 
      if(!classMap.containsKey(beanClassName)){ 
        Class<?> loadClass = urlClassLoader.loadClass(className); 
        classMap.put(className,loadClass); 
      } 
    } 
    try { 
      Method printMethod = classMap.get(beanClassName).getMethod("printBean3"); 
      printMethod.invoke(classMap.get(beanClassName).newInstance()); 
    } catch (IllegalAccessException e) { 
      e.printStackTrace(); 
    } catch (InvocationTargetException e) { 
      e.printStackTrace(); 
    } catch (NoSuchMethodException e) { 
      e.printStackTrace(); 
    } catch (InstantiationException e) { 
      e.printStackTrace(); 
    }