使用newInstance()获取和使用构造函数

import java.io.Console;
import java.nio.charset.Charset;
import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import static java.lang.System.out;

public class ConsoleCharset {
    public static void main(String... args) {
        Constructor[] ctors = Console.class.getDeclaredConstructors();
        Constructor ctor = null;
        for (int i = 0; i < ctors.length; i++) {
            ctor = ctors[i];
            if (ctor.getGenericParameterTypes().length == 0)
                break;
        }

        try {
            ctor.setAccessible(true);
            Console c = (Console) ctor.newInstance();
            Field f = c.getClass().getDeclaredField("cs");
            f.setAccessible(true);
            out.format("Console charset         :  %s%n", f.get(c));
            out.format("Charset.defaultCharset():  %s%n",
                    Charset.defaultCharset());

            // production code should handle these exceptions more gracefully
        } catch (InstantiationException x) {
            x.printStackTrace();
        } catch (InvocationTargetException x) {
            x.printStackTrace();
        } catch (IllegalAccessException x) {
            x.printStackTrace();
        } catch (NoSuchFieldException x) {
            x.printStackTrace();
        }
    }
}