Question

我正在尝试在Android上为我的应用程序实现简单的下载管理器，我使用简单的Serivce从Internet下载文件，当我使用此方法创建连接时：

private HttpURLConnection createConnection(String urlStr) throws IOException {
    URL               url  = new URL(urlStr);
    HttpURLConnection conn = (HttpURLConnection) url.openConnection();
    conn.setDoInput(true);
    conn.setDoOutput(true);
    conn.setReadTimeout(timeout);
    conn.setConnectTimeout(timeout);
    return conn;
}

我没有得到任何例外，并且可以正常使用此链接：

https://www.google.com/images/branding/googlelogo/1x/googlelogo_color_272x92dp.png

现在我想从连接中获取getInputStream()并将变量指定为：

in = new BufferedInputStream（connection.getInputStream（），BUFFER_SIZE）;

但是我收到了这个错误：

'java.io.FileNotFoundException' exception.

我可以从连接中获得文件长度，但我无法下载

   new Thread(new Runnable() {
       @Override
       public void run() {
           try {
               prepareDownload(fileUrl, filePath, lastModified);
               connection = createConnection(fileUrl);
               fileDownloadStatus = downloadStatus.DOWNLOADING;
               if (!startNewDownload) {
                   connection.setRequestProperty("Range", "bytes=" + downloadedFile.length() + "-");
               }
               if (onDownloadProcess != null)
                   onDownloadProcess.fileLength(fileLength);
               in = new BufferedInputStream(connection.getInputStream(), BUFFER_SIZE);
               long progressLength = 0;
               if (!startNewDownload) {
                   progressLength += downloadedFile.length();
                   // append to exist downloadedFile
                   writer = new FileOutputStream(filePath, true);
               } else {
                   writer = new FileOutputStream(filePath);
                   // save remote last modified data to local
                   lastModified = connection.getHeaderField("Last-Modified");
               }
               try {
                   byte[] buffer = new byte[BUFFER_SIZE];
                   int    count;
                   while (getFileDownloadStatus() == downloadStatus.DOWNLOADING && (count = in.read(buffer)) != -1) {
                       progressLength += count;
                       writer.write(buffer, 0, count);
                       // progress....
                       if (onDownloadProcess != null)
                           onDownloadProcess.onProgress((int) (progressLength * 100 / fileLength));
                       if (progressLength == fileLength) {
                           progressLength = 0;
                           setFileDownloadStatus(downloadStatus.COMPLETE);
                       }
                   }
               ...
   }).start();

Answer 1

首先，我看到您使用HttpConnection作为https网址。如果请求失败（无法找到指定的文件），您将收到FileNotFound。很可能是因为这个原因。

以下是我在我的应用中使用的WebRequest类的片段，它适用于所有https下载

        URL url = new URL(request);

        con = (HttpsURLConnection)url.openConnection();
        con.setDoOutput(true);
        con.setInstanceFollowRedirects(false);
        con.setRequestProperty("charset", "utf-8");
        con.setUseCaches(false);

        DataOutputStream wr = new DataOutputStream(con.getOutputStream());
        wr.write(postData);
        wr.flush();
        wr.close();

        // those are from my class to return the server response
        result.setResultCode(con.getResponseCode());
        result.setResultMessage(con.getResponseMessage());

        InputStream stream = con.getInputStream();
        InputStreamReader reader = new InputStreamReader(stream);
        BufferedReader br = new BufferedReader(reader);

这是针对html请求（直到文本末尾阅读），但我认为您也可以使用我在con上设置的属性进行图像下载。

Android connection.getInputStream（）返回FileNotFoundException错误

1 个答案: