当跨域无法请求的时候我们可以修改工程下config文件夹下的index.js中的dev:{}部分。dev: {
    env: require('./dev.env'),
    port: 8080,
    autoOpenBrowser: false,
    assetsSubDirectory: 'static',
    assetsPublicPath: '/',
    proxyTable: {
        '/api': {
            target: 'http://api.douban.com/v2',
            changeOrigin: true,
            pathRewrite: {
                '^/api': ''
            }
        }
    },
    // CSS Sourcemaps off by default because relative paths are "buggy"
    // with this option, according to the CSS-Loader README
    // (https://github.com/webpack/css-loader#sourcemaps)
    // In our experience, they generally work as expected,
    // just be aware of this issue when enabling this option.
    cssSourceMap: false
}