java - android中的connection.getContentLength()返回-1

Question

这是我的 kotlin 代码 override fun doInBackground

val url = URL(f_url[0])
        val connection = url.openConnection()
        connection.connect()
        // getting file length
        val lengthOfFile = connection.getContentLength()

        println(lengthOfFile.toString()+" is the length")// this returns -1

这是我的java代码，用于相同的内部protected String doInBackground(String... arg0)

URL url = new URL(downLoadUrl);
            URLConnection conection = url.openConnection();
            conection.connect();
            // this will be useful so that you can show a tipical 0-100% progress bar
            int lenghtOfFile = conection.getContentLength();// also returns -1

我在一两个月前注意到这个错误。

由于这个问题，我无法实现水平进度条

我编写了与纯java独立类相同的代码并单独测试(没有android)并且工作正常

此错误仅出现在 Android Kotlin 和 Java 中

请帮忙

Answer 1

您没有读取输入流。这应该有效:

val url = URL("https://www.google.com")
val connection = url.openConnection() as? HttpURLConnection ?: return
connection.connect()

val inputStream = connection.inputStream
val content = inputStream.bufferedReader().use { it.readText() }

println("${content.length} is the length")