java反射（java.lang.reflect) ---普通单例模式唯一性问题

Posted 2020-10-14 喜欢和习惯

1. 普通的饱汉式、饿汉式

package org.bighead.test2;

public class TestPrivate {
	private String str = "strPrivate";
	private static final TestPrivate TESTPRIVATE = new TestPrivate();
	// 饱汉式、饿汉式
	private TestPrivate() {
		super();
		System.out.println(str);
	}
	
	public TestPrivate getInstance(){
		return TESTPRIVATE;
	}
	
	public void toPrint(){
		System.out.println("私有构造-公开方法--单实例");
	}
}

反射创建实例、调用方法（实例可访问的）

package org.bighead.test2;

import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;

public class TestDefaultSub  {
	
	public static void main(String[] args) {
		Class<TestPrivate> clazz = TestPrivate.class;
		try {
			Constructor<?> constructor = clazz.getDeclaredConstructor();
			constructor.setAccessible(true);
			TestPrivate tp = (TestPrivate) constructor.newInstance();
			tp.toPrint();
		} catch (NoSuchMethodException e) {
			e.printStackTrace();
		} catch (InstantiationException e1) {
			e1.printStackTrace();
		} catch (IllegalAccessException e1) {
			e1.printStackTrace();
		} catch (InvocationTargetException e1) {
			e1.printStackTrace();
		}
	}
}

2. 并发也会影响