java反射


java反射机制完全详解

#1.反射源头 —Class类

1.1 取得Class类对象 ⭐️

public class Demo {
	public static void main(String[] args) {
		Date date = new Date();
		Class<? extends Date> class1 = date.getClass();//取得class类对象
		System.out.println(class1);//class java.util.Date
	}
}

//利用类.class获得反射的是实例划对象
public class Demo1 {
	public static void main(String[] args) {
		Date date = new Date();
		Class<? extends Date> class1 = java.util.Date.class ;//取得class类对象
		System.out.println(class1);//class java.util.Date
	}
}

//利用Class类提供的方法实例化对向
public class Demo2 {
	public static void main(String[] args) throws ClassNotFoundException {
		Class<?> forName = Class.forName("java.util.Date");
		System.out.println(forName);//class java.util.Date
	}

}

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#2.利用反射实例化对象

2.1public T newInstacne ⭐️⭐️

public class Demo3 {
	public Demo3() {
		System.out.println("^^^^");
	}
	public String toString() {
		return "######";
	}
}
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  public class Demo4 {
	public static void main(String[] args) throws ClassNotFoundException, InstantiationException, IllegalAccessException {
		Class<?> class1 = Class.forName("反射.Demo3");
		Object object = class1.newInstance();// 实例化对象
		// Demo3 demo3=new Demo3();//调用无参构造
		System.out.println(class1);
		System.out.println(object);
	}
}

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2.2。工厂设计模式

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3.取得类继承结构

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public class Demo3 extends Object implements Serializable {
	public Demo3() {
		System.out.println("^^^^");
	}

	public String toString() {
		return "######";
	}
}
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public class Demo4 {
	public static void main(String[] args)
			throws ClassNotFoundException, InstantiationException, IllegalAccessException {
		Class<?> class1 = Class.forName("反射.Demo3");
		class1.getName();// 包名.类名
		class1.getPackage();// package 包名
		class1.getPackage().getName();// 包名
		class1.getSimpleName();// 类名

		class1.getSuperclass().getName();// 父类的包名
		Class<?>[] icls = class1.getInterfaces();// [Ljava.lang.Class;@6bf256fa
		for (int i = 0; i < icls.length; i++) {
			System.out.println(icls[i].getSimpleName());//Serializable
		}

4.反射取得构造方法（invoke）

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5.反射取得方法 ⭐️⭐️⭐️

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public class Demo5 {

	public static void main(String[] args) throws ClassNotFoundException {
		 getMethodDemo();
	}
	// 获取指定Class中的公共函数
	public  static void getMethodDemo() throws ClassNotFoundException {
		Class<?> clazz = Class.forName("反射.Persion");
		Method[] methods = clazz.getMethods();
		for (int i = 0; i < methods.length; i++) {
			System.out.println(methods[i]);
		}

	}

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6.Invoke

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