//覆写shouldInterceptRequest，通过url去匹配本地资源，用本地文件替换线上资源，达到拦截替换目的
private class MyWebViewClient(private val context: Context) : WebViewClient() {

        override fun shouldInterceptRequest(
            view: WebView?,
            request: WebResourceRequest?
        ): WebResourceResponse? {
            val webResourceResponse = shouldInterceptRequest(context, request?.url)
            if (webResourceResponse  != null) {
                return webResourceResponse  
            }
            return super.shouldInterceptRequest(view, request)
        }
    }

//shouldInterceptRequest方法伪代码

 if (url.isEmpty() || !url.startsWith("http")) {
        return null
}

   //根据请求url获取本地文件用来替换线上资源
   val targetFile = getFileByUrl(url)

   //匹配资源类型
    val mimeType = when {
        relativePath.contains(".css") -> "text/css"

        relativePath.contains(".js") -> "application/x-javascript"

        relativePath.contains(".js") -> "application/x-javascript"

        //图片类型
        relativePath.contains(".jpg") || relativePath.contains(".gif") ||
                relativePath.contains(".png") || relativePath.contains(".jpeg") -> "image/*"

        //pdf
        relativePath.endsWith(".pdf") -> "application/pdf"

        //word文档
        relativePath.endsWith(".doc") || relativePath.endsWith(".docx") -> "application/msword"

        relativePath.endsWith(".ppt") -> "application/pdf"

        //表格文档
        relativePath.endsWith(".xlsx") || relativePath.endsWith(".xla") || relativePath.endsWith(".xlc") || relativePath.endsWith(
            ".xlm"
        ) || relativePath.endsWith(".xls") || relativePath.endsWith(".xlt") || relativePath.endsWith(
            ".xlw"
        ) -> "application/vnd.ms-excel"

        else -> "text/html"
    }

    val ins = FileInputStream(targetFile)
    return WebResourceResponse(mimeType, "utf-8", ins)