无法连接到 URL 时如何处理 HttpURLConnection

Question

当我的数据库是运行时，一切正常。但是什么时候不运行我的移动应用程序总是崩溃。

错误信息：

Caused by: java.net.ConnectException: Failed to connect to /httpURL.

如何解决问题？

这是我的代码：

AsyncTaskHandleJson().execute(url)    

inner class AsyncTaskHandleJson : AsyncTask<String, String, String>() {
        override fun doInBackground(vararg url: String?): String {
            var text: String
            var connection = URL(url[0]).openConnection() as HttpURLConnection
            try {
                connection.connect()
                text = connection.inputStream.use { it.reader().use { reader -> reader.readText() } }
            } finally {
                connection.disconnect()
            }
            return text
        }

        override fun onPostExecute(result: String?) {
            super.onPostExecute(result)
            handleJson(result)
        }
    }

Answer 1

由于您的代码中没有 catch 块，您目前没有捕获任何异常。

如果您想处理 ConnectException，那么您只需抓住它：

override fun doInBackground(vararg url: String?): String {
    var text = ""
    var connection: HttpURLConnection? = null

    try {
        connection = URL(url[0]).openConnection() as HttpURLConnection
        connection.connect()
        text = connection.inputStream.use {
            it.reader().use { reader ->
                reader.readText()
            }
        }
    } catch (ce: ConnectException) {
        // ConnectionException occurred, do whatever you'd like
        ce.printStackTrace()
    } catch (e: Exception) {
        // some other Exception occurred
        e.printStackTrace()
    } finally {
        connection?.disconnect()
    }

    return text
}

查看 Exceptions reference。

无法连接到 URL 时如何处理 HttpURLConnection

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