Java核心技術--第五章5.7.3 利用反射分析類的能力

重點

1.控制域：modifiers :

如 public static final

2.參數：param

java.lang.Object

輸出樣例

enter class name(e.g.java.util.Date):
java.lang.Double
public final class java.lang.Double extendsjava.lang.Number
{
接口打印
public java.lang.Double(double);
public java.lang.Double(java.lang.String);
方法打印
public retype:boolean equals(/param:java.lang.Object);
public static retype:java.lang.String toString(/param:double);
public retype:java.lang.String toString(/);
public retype:int hashCode(/);
public static retype:int hashCode(/param:double);
public static retype:double min(/param:double , param:double);
public static retype:double max(/param:double , param:double);
public static native retype:long doubleToRawLongBits(/param:double);
public static retype:long doubleToLongBits(/param:double);
public static native retype:double longBitsToDouble(/param:long);
public volatile retype:int compareTo(/param:java.lang.Object);
public retype:int compareTo(/param:java.lang.Double);
public retype:byte byteValue(/);
public retype:short shortValue(/);
public retype:int intValue(/);
public retype:long longValue(/);
public retype:float floatValue(/);
public retype:double doubleValue(/);
public static retype:java.lang.Double valueOf(/param:java.lang.String);
public static retype:java.lang.Double valueOf(/param:double);
public static retype:java.lang.String toHexString(/param:double);
public static retype:int compare(/param:double , param:double);
public static retype:boolean isNaN(/param:double);
public retype:boolean isNaN(/);
public static retype:boolean isFinite(/param:double);
public static retype:boolean isInfinite(/param:double);
public retype:boolean isInfinite(/);
public static retype:double sum(/param:double , param:double);
public static retype:double parseDouble(/param:java.lang.String);
調用域
modifiers :public static final name: double POSITIVE_INFINITY;
modifiers :public static final name: double NEGATIVE_INFINITY;
modifiers :public static final name: double NaN;
modifiers :public static final name: double MAX_VALUE;
modifiers :public static final name: double MIN_NORMAL;
modifiers :public static final name: double MIN_VALUE;
modifiers :public static final name: int MAX_EXPONENT;
modifiers :public static final name: int MIN_EXPONENT;
modifiers :public static final name: int SIZE;
modifiers :public static final name: int BYTES;
modifiers :public static final name: java.lang.Class TYPE;
modifiers :private final name: double value;
modifiers :private static final name: long serialVersionUID;
}

源代碼

package com.hostman.corejava;

import java.awt.print.Paper;
import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.util.Scanner;



import experiment1.class1;


/**
 * print all feature of a class
 * @author douer
 *
 */
public class ReflectionTest {

	public static void main(String[] args) 
	{
		// TODO Auto-generated method stub
		//read class name from command line args or user input
		String name;
		if(args.length>0)name=args[0];
		else
		{
			Scanner in=new Scanner(System.in);
			System.out.println("enter class name(e.g.java.util.Date):");
			name=in.next();//name獲取輸入的包名
		}
		
		try 
		{
			//print class name and superclass name
			/*
			 * 可以使用Modifier類中的isPublic、isPrivate或isFinal判斷方法或構造器
			 * 是否是public、private或final。我們需要做的全部工作就是調用Modifier類的相應方法，並對返回的整型數值進行分析，
			 * 另外，還可以利用Modifier.toString方法將修飾法打印出來。
			 */
			//name的包名
			Class cl=Class.forName(name); 
			Class superc1=cl.getSuperclass();//父類
			String modifiers=Modifier.toString(cl.getModifiers());
			//輸出控制範圍如public，private
			if(modifiers.length()>0)System.out.print(modifiers+" ");
			//輸出類的名字
			System.out.print("class "+name);
			//c1有超類---------------------------
			if(superc1!=null&&superc1!=Object.class)
				System.out.print(" extends"+superc1.getName());
			
			System.out.print("\n{\n");
			//調用接口打印
			System.out.println("接口打印");
			printConstructor(cl);
			System.out.println();
			//調用方法打印
			System.out.println("方法打印");
			printMethods(cl);
			System.out.println();
			//調用域
			System.out.println("調用域");
			printFields(cl);
			System.out.println("}");
		}
		catch(ClassNotFoundException e)
		{
			e.printStackTrace();
		}
		System.exit(0);
		
	}	
	
	/**
	 * print all fields of a class
	 * 如：私有變量
	 * @param cl
	 */
	
	private static void printFields(Class cl) {
		// TODO Auto-generated method stub
		Field[] fields=cl.getDeclaredFields();
		
		for(Field f:fields)
		{
			Class type=f.getType();
			String name=f.getName();
			System.out.print("   ");
			//打印域的控制範圍
			String modifiers=Modifier.toString(f.getModifiers());
			if(modifiers.length()>0)System.out.print("modifiers :"+modifiers+" ");
			System.out.println("name: "+type.getName()+" "+name+";");
		}
	}

	private static void printMethods(Class cl)
	{
		// TODO Auto-generated method stub
		Method[] methods=cl.getDeclaredMethods();
		
		for(Method m:methods)
		{
		    //獲取方法返回的類型 如int
			Class retType=m.getReturnType();
			String name=m.getName();//方法的名字
			
			System.out.print("     ");
			//print modifier,return type method name
			//
			String modifiers=Modifier.toString(m.getModifiers()); 
			if(modifiers.length()>0)System.out.print(modifiers+" ");//public static
			
			System.out.print(" retype:"+retType.getName()+" "+name+"(/");//返回類型
			
			//print 參數parameter
			Class[] paramTypes=m.getParameterTypes();
			//依次打印參數
			for(int j=0;j<paramTypes.length;j++)
			{
				if(j>0)System.out.print(" , ");
				System.out.print("param:"+paramTypes[j].getName());
				//param:double , param:double
			}
			System.out.println(");");//打印完了要換行
		}
			
	}
		



//test::java.lang.Double




	/**
	 * print cl all constructor
	 * 
	 */
	public static void printConstructor(Class cl) {
		//所有接口計入數組
		Constructor[] constructors=cl.getDeclaredConstructors();
		/*getModifiers的方法，它將返回一個整型數值，
		*用不同的位開關描述public和static這樣的修飾符使用狀況。
		*/
		for(Constructor c:constructors) 
		{
			String name=c.getName();
			System.out.print("     ");
			//modifiers表示控制域如： public
			String  modifiers=Modifier.toString(c.getModifiers());
			if(modifiers.length()>0)System.out.print(modifiers+" ");
			//打印包名
			System.out.print(name+"(");
			
			//print parameter types
			Class[] paramTypes=c.getParameterTypes();//獲取參數類型
			for(int j=0;j<paramTypes.length;j++)
			{
				if(j>0)System.out.print(" , ");
				System.out.print(paramTypes[j].getName());
			}
			System.out.println(");");
		}
	}

}