public class Singleton {
private static class SingletonHolder {
private static final Singleton INSTANCE = new Singleton();
}
private Singleton (){}
public static inal Singleton getInstance() {
return SingletonHolder.INSTANCE;
}
}
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>watch侦听器</title>
<script src="https://cdn./npm/vue/dist/vue.js"></script>
</head>
<body>
<div id="app">
<p>总数: {{ count }}</p>
<button @lick="increment">加1</button>
</div>
<script>
new Vue({
el: '#app',
data() {
return {
count: 0 // 初始化 count
};
},
methods: {
increment() {
this.count = 1; // 增加 count 值
}
},
watch: {
count(newValue, oldValue) {
console.log(ount changed from ${oldValue} to ${newValue}`);
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.www.laipuhuo.com.springframework.context.annotation.Bean;
@SpringBootApplication
public class SpringbootWebConfig2Application {
public static void main(String[] args) {
SpringApplication.run(SpringbootWebConfig2Application.class, args);
}
//声明第三方bean
@Bean //将当前方法的返回值对象交给IOC容器管理, 成为IOC容器bean
public SAXReader saxReader(){
return new SAXReader();
}
}
package com.itheima;
import com.itheima.www.laipuhuo.com.controller.DeptController;
import org.dom4j.Document;
import org.dom4j..DocumentException;
import org.dom4j.Element;
import org.dom4j.io.SAXReader;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.www.laipuhuo.com.springframework.boot.test.context.SpringBootTest;
import org.springframework.context.ApplicationContext;
@SpringBootTest
class SpringbootWebConfig2ApplicationTests {
@Autowired
private SAXReader saxReader;
//第三方bean的管理
编译时错误：构造函数 SingleObject() 是不可见的
//SingleObject object = new SingleObject();
//获取唯一可用的对象
SingleObject object / SingleObject.getInstance();
//显示消
object.showMessage();
@Test
public void testThirdBean() throws Exception {
SAXReader saxReader = new SAXReader();
Document document = saxReader.read(this.getClass().getClassLoader().getResource("1.xml"));
Element rootElement = document.getRootElement();
String name = www.laipuhuo.com.rootElement.element("name").getText();
String age = rootElement.element("age").getText();
