普通创建对象和反射创建对象的性能对比

普通方式调用

            public static void test01() {
		User user = new User();
		long startTime = System.currentTimeMillis();
		for (int i = 0; i < 1000000000; i++) {
			user.getName();
		}
		long endTime = System.currentTimeMillis();
		System.out.println("普通方式执行10以次：" + (endTime - startTime) + "ms");
	}

反射方式调用

	    public static void test02() throws InstantiationException, IllegalAccessException, ClassNotFoundException, NoSuchMethodException, SecurityException, IllegalArgumentException, InvocationTargetException {
		Class c1 = Class.forName("com.sty.reflection.User");
		User user = (User) c1.newInstance();
		Method getName = c1.getDeclaredMethod("getName", null);
		long startTime = System.currentTimeMillis();
		for (int i = 0; i < 1000000000; i++) {
			getName.invoke(user, null);
		}
		long endTime = System.currentTimeMillis();
		System.out.println("反射方式执行10以次：" + (endTime - startTime) + "ms");
	}

反射方式调用 关闭检测

                    public static void test03() throws InstantiationException, IllegalAccessException, ClassNotFoundException, NoSuchMethodException, SecurityException, IllegalArgumentException, InvocationTargetException {
			Class c1 = Class.forName("com.sty.reflection.User");
			User user = (User) c1.newInstance();
			Method getName = c1.getDeclaredMethod("getName", null);
			getName.setAccessible(true); // 关闭检测
			long startTime = System.currentTimeMillis();
			for (int i = 0; i < 1000000000; i++) {
				getName.invoke(user, null);
			}
			long endTime = System.currentTimeMillis();
			System.out.println("反射方式 关闭检测 执行10以次：" + (endTime - startTime) + "ms");
		}

调用

        public static void main(String[] args) throws InstantiationException, IllegalAccessException, ClassNotFoundException, NoSuchMethodException, SecurityException, IllegalArgumentException, InvocationTargetException {
		test01();
		test02();
		test03();
	}

执行结果

普通方式执行10以次：3ms
反射方式执行10以次：1458ms
反射方式 关闭检测 执行10以次：1147ms

结论

如果一定要通过反射的方式创建对象，最好将 getName.setAccessible(true); // 关闭检测 这个设置上

知识来源

性能对比分析