打印一个类全部信息的方法

package chapter3Demos;

import java.lang.reflect.Method;
import java.util.Scanner;
import java.lang.reflect.*;

import source.Superman;

public class Demo3_3_2 {

    public static void main(String[] args)  {
        String name;
        if(args.length > 0) name = args[0];
        else {
            Scanner in = new Scanner(System.in);
            System.out.println("Enter class anem(e.g. java.util.Date):");
            name = in.next();
        }
        
        try {
            Class cl = Class.forName(name);
            Class supercl = cl.getSuperclass();
            String modifiers = Modifier.toString(cl.getModifiers());
            if (modifiers.length() > 0) {
                System.out.print(modifiers + " ");
            }
            System.out.print("class" + name);
            if (supercl != null && supercl != Object.class) {
                System.out.print("extends" + supercl.getName());
            }
            
            System.out.println("
{
");
            printConstructors(cl);
            System.out.println();
            printMethods(cl);
            System.out.println();
            printFields(cl);
            System.out.println("}");
         }catch(ClassNotFoundException e) {
             e.printStackTrace();
         }
        System.exit(0);
    }

    private static void printFields(Class cl) {
        Field[] fields = cl.getDeclaredFields();
        
        for(Field f : fields) {
            System.out.print("  ");
            String modifiers = Modifier.toString(f.getModifiers());
            if (modifiers.length() > 0) {
                System.out.print(modifiers + " ");
            }
            
            Class type = f.getType();
            String name = f.getName();
            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("  ");
            //print modifiers, return type and method name
            String modifiers = Modifier.toString(m.getModifiers());
            if(modifiers.length() > 0) {
                System.out.print(modifiers + " ");
            }
            System.out.print(retType.getName() + " " + name + "(");
            //print parameter types
            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 printConstructors(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 + " ");
            
            //print parameter types
            Class[] paramTypes = c.getParameterTypes();
            for (int i = 0; i < paramTypes.length; i++) {
                if(i > 0) System.out.print(", ");
                System.out.print(paramTypes[i].getName());
            }
            System.out.println(");");
        }
        
    }
}

输入java.lang.Double

将得到

public final classjava.lang.Doubleextendsjava.lang.Number
{

  public java.lang.Double double);
  public java.lang.Double java.lang.String);

  public boolean equals(java.lang.Object);
  public static java.lang.String toString(double);
  public java.lang.String toString();
  public int hashCode();
  public static int hashCode(double);
  public static double min(double, double);
  public static double max(double, double);
  public static native long doubleToRawLongBits(double);
  public static long doubleToLongBits(double);
  public static native double longBitsToDouble(long);
  public volatile int compareTo(java.lang.Object);
  public int compareTo(java.lang.Double);
  public byte byteValue();
  public short shortValue();
  public int intValue();
  public long longValue();
  public float floatValue();
  public double doubleValue();
  public static java.lang.Double valueOf(java.lang.String);
  public static java.lang.Double valueOf(double);
  public static java.lang.String toHexString(double);
  public static int compare(double, double);
  public static boolean isNaN(double);
  public boolean isNaN();
  public static boolean isFinite(double);
  public static boolean isInfinite(double);
  public boolean isInfinite();
  public static double sum(double, double);
  public static double parseDouble(java.lang.String);

  public static final double POSITIVE_INFINITY;
  public static final double NEGATIVE_INFINITY;
  public static final double NaN;
  public static final double MAX_VALUE;
  public static final double MIN_NORMAL;
  public static final double MIN_VALUE;
  public static final int MAX_EXPONENT;
  public static final int MIN_EXPONENT;
  public static final int SIZE;
  public static final int BYTES;
  public static final java.lang.Class TYPE;
  private final double value;
  private static final long serialVersionUID;
}