Java code lib 反射查询类结构

import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;

public class ReflectionDemo {
    public static void main(String[] args) {
        ReflectionDemo.paresClass("java.util.Date");
    }

    public static void paresClass(String className) {

        try {
            Class cl = Class.forName(className);
            cl.getComponentType();
            Class supercl = cl.getSuperclass();
            String modifiers = Modifier.toString(cl.getModifiers());
            if (modifiers.length() > 0) {
                System.out.print(modifiers + " ");
            }
            System.out.print("class" + className);
            if (supercl != null && supercl != Object.class) {
                System.out.print(" extends " + supercl.getName());
            }
            System.out.print("\n{\n");
            printConstructor(cl);
            System.out.println();
            printMethods(cl);
            System.out.println();
            printFields(cl);
            System.out.println();
        } catch (Exception e) {

        }
    }

    private static void printFields(Class cl) {
        Field[] fields = cl.getDeclaredFields();
        for (Field f : fields) {
            Class type = f.getType();
            String name = type.getName();
            System.out.print(" ");
            String modifiers = Modifier.toString(f.getModifiers());
            if (modifiers.length() > 0) {
                System.out.print(modifiers + " ");
            }
            System.out.println(type.getName() + " " + name + ";");
        }
    }

    private static void printMethods(Class cl) {
        Method[] methods = cl.getDeclaredMethods();
        for (Method m : methods) {
            Class retType = m.getReturnType();
            String name = m.getName();

            System.out.print(" ");
            String modifiers = Modifier.toString(m.getModifiers());
            if (modifiers.length() > 0) {
                System.out.print(modifiers + " ");
            }
            System.out.print(retType.getName() + " " + name + "(");
            Class[] paramTypes = m.getParameterTypes();
            for (int j = 0; j < paramTypes.length; j++) {
                if (j > 0) {
                    System.out.print(",");
                }
                System.out.print(paramTypes[j].getName());
            }
            System.out.println(");");
        }
    }

    private static void printConstructor(Class cl) {
        Constructor[] constructors = cl.getDeclaredConstructors();
        for (Constructor c : constructors) {
            String name = c.getName();
            System.out.print("  ");
            String modifiers = Modifier.toString(c.getModifiers());
            if (modifiers.length() > 0) {
                System.out.print(modifiers + " ");
            }
            System.out.print(name + "(");
            Class[] paramTypes = c.getParameterTypes();
            for (int j = 0; j < paramTypes.length; j++) {
                if (j > 0) {
                    System.out.print(",");
                }
                System.out.print(paramTypes[j].getName());
            }
            System.out.println(");");
        }
    }
}