Java通過反射調(diào)用方法

package com.wkcto.chapter08.demo02;

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

/**
 * 通過反射調(diào)用方法
 * 		method.invoke( 實例名,  方法的實參列表) 
 * 		如果是靜態(tài)方法, 實例名位置傳遞null
 * @author 蛙課網(wǎng)
 *
 */
public class Test03 {

	public static void main(String[] args) throws Exception {
		//1)創(chuàng)建Class對象
		Class<?> class1 = String.class;
		
		//2) 通過Class對象創(chuàng)建實例
		Object str1 = class1.newInstance();  		//new String();
		//通過構(gòu)造方法創(chuàng)建實例,  String( byte[] )  	根據(jù)字節(jié)數(shù)組創(chuàng)建字符串
		Constructor<?> constructor = class1.getConstructor( byte[].class );
		byte[] bytes = "wkcto".getBytes();  		//返回字符串對應(yīng)的字節(jié)數(shù)組
		Object str2 = constructor.newInstance(bytes);
		
		//3)反射length()方法
		Method lengthM = class1.getMethod("length");
		//方法調(diào)用, invoke( 實例名,  該方法的實參列表)
		Object len = lengthM.invoke(str1, null); 		//str1.length()
		System.out.println( len );
		len = lengthM.invoke(str2); 
		System.out.println( len );
		
		//4)反射equals(Object)
		Method equalsM = class1.getMethod("equals", Object.class);
		Object result = equalsM.invoke(str1, str2);   //str1.equals(str2)
		System.out.println( result );
		
		//5)反射substring( int, int )
		Method substringM = class1.getMethod("substring",  int.class, int.class);
		Object sub = substringM.invoke(str2, 0,2); 		//str2.substring(0,2)
		System.out.println( sub );
		
		//6)反射靜態(tài)方法 valueOf(int)
		Method valueOfM = class1.getMethod("valueOf", int.class);
		Object text = valueOfM.invoke(null, 258);
		System.out.println( text instanceof String );
	}

}