Java reflection calls the main method, and the private method implements

Recent research jetty source code, found that the code inside the container can not understand, are all Java syntax, is basically reflective + design mode + configuration file. Very inexplicable wonderful method of calling. There is a call to the main method of reflection, the result is not understood, so we study the reflection function. Because of the reflection of the article on the Internet too much, I mainly studied the main method, private method of the call. as follows, reflection invokes the HelloWorld class method. The HelloWorld classes are as follows:

public class HelloWorld {public 
    static void Main (string[] args) {
        System.out.println ("HelloWorld");
    }
    private void prt (String msg) {
        System.out.println (msg);
    }
}

Invoke the Main method as follows:

public class Helloworldrefection {public 
    static void Main (string[] args) throws Instantiationexception, Illegalaccessexception, 
        SecurityException, Nosuchmethodexception, IllegalArgumentException, InvocationTargetException {Method Method
        = HelloWorld.class.getMethod ("main", String[].class);
        Method.invoke (null, (Object) New string[]{});
    }

Invoke the private method as follows:

public class Helloworldrefection {public 
    static void Main (string[] args) throws Instantiationexception, Illegalaccessexception, 
    SecurityException, Nosuchmethodexception, IllegalArgumentException, invocationtargetexception {
        Class clazz = helloworld.class;
        HelloWorld HelloWorld = HelloWorld.class.newInstance ();
        Method[] methods = Clazz.getdeclaredmethods ();
        For (method Method:methods) {
            System.out.println (Method.getname ());
            if (Method.getname (). Equals ("PRT")) {
                method.setaccessible (true);
                Method.invoke (HelloWorld, "Hello");}}}

Summarize:
1 Invoking the Main method requires that the main method's argument is string[], but when Method.invoke, the string[is required to be cast to object, and for the reason, many on the web say this, The main is that the JDK executes the main method by dividing the string[] into multiple parameters, and so on. After I analyzed the source code, will be the issue of a special article to write out.
2 Calling the private method requires that before calling this method, you need to set the method of this execution to the following, instead of just finding a place to run the method.setaccessible (true).
3 When a method is invoked dynamically using reflection, it is primarily with the Method.invoke () method, and if it is a static method, the first parameter of invoke is set to NULL, and if it is not a static method, the first argument is set to the object generated by the class.