[移动开发]Android WebView判定网页加载的错误，面试篇

     view: WebView?,
    request: WebResourceRequest?,
    error: WebResourceError?
) {
    super.onReceivedError(view, request, error)
    Log.d(TAG, "onReceivedError: request= " + request.json())
    Log.d(TAG, "onReceivedError: error= " + error.json())
}

}
webview.loadUrl(“https://www.baidu.com/”)

**request输出：**

> {"a":{"a":"[www.baidu.com/","b":true,…]( ) (Linux; Android 11; sdk\_gphone\_x86\_arm Build/RSR1.200819.001.A1; wv) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/83.0.4103.106 Mobile Safari/537.36","Accept":"text/html,application/xhtml+xml,application/xml;q\\u003d0.9,image/webp,image/apng,_/_;q\\u003d0.8,application/signed-exchange;v\\u003db3;q\\u003d0.9","Upgrade-Insecure-Requests":"1"}}}

**error输出：**

> {"a":{"a":-1,"b":"net::ERR\_CACHE\_MISS"}}

/**

• 需要注意的是：与老版本不同，新版本已经针对所有的资源加载错误都会回调*(iframe, image, etc.), 不仅仅是加载的主页面
  */
  public void onReceivedError(WebView view, WebResourceRequest request, WebResourceError error) {
  if (request.isForMainFrame()) {
  onReceivedError(view,
  error.getErrorCode(), error.getDescription().toString(),
  request.getUrl().toString());
  }
  }

所以，通过以上监听，即可知道对应的错误内容，进而做相应的业务处理。

三 常见的错误案例分析
-----------

### 1.错误：ERR\_UNKNOWN\_URL\_SCHEME

**复现条件**:打开百度新闻资讯网页，并点击评论

![在这里插入图片描述](https://p3-juejin.byteimg.com/tos-cn-i-k3u1fbpfcp/9dd21da05207430a80adb2873dbc70f4~tplv-k3u1fbpfcp-zoom-1.image)

| 载体 | 现象 |
| --- | --- |
| App内置WebView | 报错：ERR\_UNKNOWN\_URL\_SCHEME |
| UC、华为浏览器 | 停留在当前页面状态 |
| Chrome浏览器 | 跳转到百度APP内部打开 |

来看一下页面加载shouldOverrideUrlLoading 中回调request输出：

> {"a":{"a":"baiduboxapp://v1/easybrowse/hybrid?upgrade\\u003d1\\u0026type\\u003dhybrid\\u0026tpl\_id\\u003dlanding\_app.html\\u0026newbrowser\\u003d1\\u0026style\\u003d%7B%22toolbaricons%22%3A%7B%22tids%22%3A%5B%224%22%2C%221%22%2C%222%22%2C%223%22%5D%2C%22menumode%22%3A%222%22%2C%22actionBarConfig%22%3A%7B%22extCase%22%3A%220%22%7D%7D%7D\\u0026slog\\u003d%7B%22from%22%3A%22feed%22%7D\\u0026context\\u003d%7B%22nid%22%3A%22news\_9777178803801641010%22%7D\\u0026ch\_url\\u003dhttps%3A%2F%2Fmbd.baidu.com%2Fnewspage%2Fdata%2Flandingreact%3FpageType%3D2%26nid%3Dnews\_9777178803801641010%26uk%3D%26sourceFrom%3DlandingShare\\u0026commentInfo\\u003d%7B%22topic\_id%22%3A1066000039731532%2C%22opentype%22%3A2%7D\\u0026logargs\\u003d%7B%22source%22%3A%221020283l%22%2C%22channel%22%3A%221020283m%22%7D\\u0026needlog\\u003d1","b":false,"c":true,"d":false,"e":"GET","f":{"Accept":"text/html,application/xhtml+xml,application/xml;q\\u003d0.9,image/avif,image/webp,image/apng,_/_;q\\u003d0.8,application/signed-exchange;v\\u003db3;q\\u003d0.9","Referer":"[mbd.baidu.com/newspage/da…]( )

> 可以发现协议不是http类开头，而是百度自己定义的"baiduboxapp"。因此，不做处理，当然是识别不了的。

### 2.实现UC、华为浏览器处理的效果——>无视

webview.webViewClient = object : WebViewClient() {
override fun shouldOverrideUrlLoading(
view: WebView?,
request: WebResourceRequest?
): Boolean {
Log.d(TAG, “shouldOverrideUrlLoading: KaTeX parse error: Expected '}', got 'EOF' at end of input: …lLoading: url->{request?.url}”)
if (view != null && request?.url?.toString() != null) {
if (request.url.toString().startsWith(“http”)) {
view.loadUrl(request.url.toString())
}
return true
}

### 3.如何实现Chrome浏览器处理的效果——>能跳转

假定这是百度适配Chrome的效果，而不是Chrome主动去适配百度的代码页面，那么说明客户端的WebView也是能做到这样效果的。

基于此，我们来urldecode一下协议内容来看看request有什么特殊：

> baiduboxapp://v1/easybrowse/hybrid?upgrade=1&type=hybrid&tpl\_id=landing\_app.html&newbrowser=1&style={"toolbaricons":{"tids":\["4","1","2","3"\],"menumode":"2","actionBarConfig":{"extCase":"0"}}}&slog={"from":"feed"}&context={"nid":"news\_9777178803801641010"}&ch\_url=[mbd.baidu.com/newspage/da…]( )

整体来看，仍旧是符合URI规则的。这样的话就可以考虑使用Intent处理的方式了。

webview.webViewClient = object : WebViewClient() {
override fun shouldOverrideUrlLoading(
view: WebView?,
request: WebResourceRequest?
): Boolean {
Log.d(TAG, “shouldOverrideUrlLoading: KaTeX parse error: Expected '}', got 'EOF' at end of input: …lLoading: url->{request?.url}”)
if (view != null && request?.url?.toString() != null) {
if (request.url.toString().startsWith(“http”)) {
view.loadUrl(request.url.toString())
} else {
try {
Log.d(TAG, “shouldOverrideUrlLoading: 开始跳转”)
startActivity(Intent(Intent.ACTION_VIEW, request.url))
} catch (e: Exception) {