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别名路径：①npm install path --save-dev②配置

// vite.config,js
import { defineConfig } from 'vite'
import vue from '@vitejs/plugin-vue'import { viteStaticCopy } from 'vite-plugin-static-copy'
import path from 'path'
export default defineConfig({resolve: {alias: {'@': path.resolve(__dirname, './src') // 使用 Vite 的 resolve 方法}},plugins: [vue(),],server: {fs: {// 允许从一个级别到项目根目录提供文件allow: ['..']},middlewareMode: false,proxy: {'/api': {// 指定目标服务器的地址target: 'http://baidu.com',// changeOrigin: 设置为 true 时，会修改请求头中的 host 字段为目标服务器的主机名，这有助于解决某些服务器对 host 头的严格检查changeOrigin: true,// 用于重写请求路径。这里将所有以 /api 开头的路径重写为空字符串，即去掉 /api 前缀。pathRewrite: { '^/api': '' },// 添加日志记录 设置为 debug 可以在控制台中输出详细的代理日志，帮助调试。logLevel: 'debug', // 添加错误处理回调函数，捕获代理请求中的错误，并返回适当的错误响应onError: (err, req, res) => {console.error('Proxy error:', err);res.status(500).send('Proxy error: ' + err.message);}}},}
})

一、 使用 switch 语句和 Vue 的动态类绑定

<template><div :class="['a-bg', titleClass]"></div>
</template><script setup>
import { ref, computed } from "vue";
// 随机赋值
// 定义一个数组，包含可能的值
const possibleValues = ['one', 'two', 'three'];// 生成一个随机索引
const randomIndex = Math.floor(Math.random() * possibleValues.length);// 根据随机索引设置 systemTitle 的值
const systemTitle = ref(possibleValues[randomIndex]);const titleClass = computed(() => {switch (systemTitle.value) {case 'one':return 'one';case 'two':return 'two';default:return 'three';}
});</script><style lang="scss" scoped>
#app {width: 100%;height: 100vh;
}.a-bg {width: 200px;height: 200px;background: linear-gradient(45deg, #fff, red);position: relative;/* 确保伪元素相对于父元素定位 */&::before {content: '';display: block;/* 设置伪元素的显示方式 */position: absolute;/* 确保伪元素绝对定位 */top: 0;left: 0;// src\assets\image\cat1.jpgbackground: url("/src/assets/image/cat1.jpg") no-repeat center;background-size: 100% 100%;width: 200px;height: 200px;}
}.one::before {background: url("/src/assets/image/cat1.jpg") no-repeat center;background-size: 100% 100%;
}.two::before {// 绝对路径 从项目的根目录开始计算background: url("/src/assets/image/cat2.jpg") no-repeat center;background-size: 100% 100%;
}.three::before {// 别名路径 用了 @ 别名，指向 src 目录下的路径background: url("@/assets/image/cat3.jpg") no-repeat center;background-size: 100% 100%;
}
</style>

二、使用classList.add()和ref实例

<template><div ref="titleImage" class='a-bg'></div>
</template><script setup>
import { ref, watch, onMounted } from "vue";// 随机赋值
const possibleValues = ['one', 'two', 'three'];
const randomIndex = Math.floor(Math.random() * possibleValues.length);
const systemTitle = ref(possibleValues[randomIndex]);const titleImage = ref(null);const updateTitleImageClass = () => {if (titleImage.value) {console.log('Before:', titleImage.value.className); // 打印当前类名titleImage.value.className = 'a-bg ' + systemTitle.value; // 直接设置类名// titleImage.value.classList.add(`${systemTitle.value}`);console.log('After:', titleImage.value.className); // 打印替换后的类名}
};onMounted(() => {console.log(systemTitle.value, 'systemTitle');updateTitleImageClass();
});// 监听 systemTitle 的变化
watch(systemTitle, updateTitleImageClass);
</script><style lang="scss" scoped>
#app {width: 100%;height: 100vh;
}.a-bg {width: 200px;height: 200px;background: linear-gradient(45deg, #fff, red);position: relative;&::before {content: '';display: block;position: absolute;top: 0;left: 0;background: url("/src/assets/image/cat1.jpg") no-repeat center;background-size: 100% 100%;width: 200px;height: 200px;}
}.one::before {background: url("/src/assets/image/cat1.jpg") no-repeat center;background-size: 100% 100% !important;
}.two::before {background: url("/src/assets/image/cat2.jpg") no-repeat center;background-size: 100% 100% !important;
}.three::before {background: url("@/assets/image/cat3.jpg") no-repeat center;background-size: 100% 100% !important;
}
</style>

三、对象映射（类名和图片）

<template><div ref="titleImage" :class="['a-bg', systemTitle.value]"></div>
</template><script setup>
import { ref, watch, onMounted } from "vue";// 随机赋值
const possibleValues = ['one', 'two', 'three'];
const randomIndex = Math.floor(Math.random() * possibleValues.length);
const systemTitle = ref(possibleValues[randomIndex]);const titleImage = ref(null);// 对象映射
const classMapping = {one: 'cat1',two: 'cat2',three: 'cat3'
};const updateTitleImageClass = () => {if (titleImage.value) {console.log('Before:', titleImage.value.className); // 打印当前类名// 清除所有可能的类名for (const key in classMapping) {titleImage.value.classList.remove(key);}// 添加新的类名titleImage.value.classList.add(systemTitle.value);console.log('After:', titleImage.value.className); // 打印替换后的类名}
};onMounted(() => {console.log(systemTitle.value, 'systemTitle');updateTitleImageClass();
});// 监听 systemTitle 的变化
watch(systemTitle, updateTitleImageClass);
</script><style lang="scss" scoped>
#app {width: 100%;height: 100vh;
}.a-bg {width: 200px;height: 200px;background: linear-gradient(45deg, #fff, red);position: relative;&::before {content: '';display: block;position: absolute;top: 0;left: 0;background: url("/src/assets/image/cat1.jpg") no-repeat center;background-size: 100% 100%;width: 200px;height: 200px;}
}.one::before {background: url("/src/assets/image/cat1.jpg") no-repeat center;background-size: 100% 100% !important;
}.two::before {background: url("/src/assets/image/cat2.jpg") no-repeat center;background-size: 100% 100% !important;
}.three::before {background: url("@/assets/image/cat3.jpg") no-repeat center;background-size: 100% 100% !important;
}
</style>

四、import.meta.glob

<template><div ref="titleImage" :class="['a-bg', systemTitle.value]"></div>
</template><script setup>
import { ref, watch, onMounted } from "vue";// 随机赋值
const possibleValues = ['one', 'two', 'three'];
const randomIndex = Math.floor(Math.random() * possibleValues.length);
const systemTitle = ref(possibleValues[randomIndex]);const titleImage = ref(null);// 动态导入图片
const images = import.meta.glob('@/assets/image/*.jpg');// 对象映射
const classMapping = {one: 'cat1',two: 'cat2',three: 'cat3'
};const updateTitleImageClass = async () => {if (titleImage.value) {console.log('Before:', titleImage.value.className); // 打印当前类名// 清除所有可能的类名for (const key in classMapping) {titleImage.value.classList.remove(key);}// 添加新的类名titleImage.value.classList.add(systemTitle.value);console.log('After:', titleImage.value.className); // 打印替换后的类名// 动态加载图片const imagePath = `/src/assets/image/${classMapping[systemTitle.value]}.jpg`; // 根据系统标题获取图片路径const imageModule = await images[imagePath]();  // 使用动态导入const imageUrl = imageModule.default; // 获取图片路径titleImage.value.style.backgroundImage = `url(${imageUrl})`; // 设置背景图片}
};onMounted(() => {console.log(systemTitle.value, 'systemTitle');updateTitleImageClass();
});// 监听 systemTitle 的变化
watch(systemTitle, updateTitleImageClass);
</script><style lang="scss" scoped>
#app {width: 100%;height: 100vh;
}.a-bg {width: 200px;height: 200px;background: linear-gradient(45deg, #fff, red);position: relative;background-size: 100% 100%;
}.one::before,
.two::before,
.three::before {content: '';display: block;position: absolute;top: 0;left: 0;width: 100%;height: 100%;
}
</style>