这是不正确的使用还是类加载器的不良做法？

Question

我的程序被设计为从一个可运行的jar文件启动，如果需要的话将所有东西都设置好，然后在另一个jar文件中加载一个类来启动程序。这允许自我更新，重新启动等。嗯，类加载代码我似乎有点时髦。以下是我用来加载程序的代码。这是不正确的使用还是不好的做法？

try { 
     Preferences.userRoot().put("clientPath", Run.class.getProtectionDomain().getCodeSource().getLocation().toURI().toString()); //Original client location; helps with restarts 
    } catch (URISyntaxException e1) { 
     e1.printStackTrace(); 
    } 

    try { 
     Preferences.userRoot().flush(); 
    } catch (BackingStoreException e1) { 
     e1.printStackTrace(); 
    } 


    File file = new File(path); // path of the jar we will be launching to initiate the program outside of the Run class 
    URL url = null; 
    try { 
     url = file.toURI().toURL(); // converts the file path to a url 
    } catch (MalformedURLException e) { 
     e.printStackTrace(); 
    } 
    URL[] urls = new URL[] { url }; 
    ClassLoader cl = new URLClassLoader(urls); 

    Class cls = null; 
    try { 
     cls = cl.loadClass("com.hexbit.EditorJ.Load"); // the class we are loading to initiate the program 
    } catch (ClassNotFoundException e) { 
     e.printStackTrace(); 
    } 

    try { 
     cls.newInstance(); // starts the class that has been loaded and the program is on its way 
    } catch (InstantiationException e) { 
     e.printStackTrace(); 
    } catch (IllegalAccessException e) { 
     e.printStackTrace(); 
    } 

Answer 1

你有最大的问题是，当你得到你假装记录异常使得OK继续，仿佛什么都没有发生异常。

如果您将try/catch块聚合在一起，那么您的代码将会更短且更易于阅读，并且不会认为异常并不重要。

试试这个例子

public static Object load(String path, String className) { 
    try { 
     URL url = new File(path).toURI().toURL(); 
     ClassLoader cl = new URLClassLoader(new URL[] { url }); 
     return cl.loadClass(className).newInstance(); 
    } catch (Exception e) { 
     throw new IllegalStateException("Unable to load "+className+" " + e); 
    } 
}