从重定向到 HTTPS 连接的 HTTP 连接下载文件

Question

我在项目中使用 Dropbox 从 dropbox 获取小网址，类似于 http://www.db.tt/xyzabc 。

当我尝试在 HTC My touch 中下载文件时，我的代码工作正常，但如果我在 Motorola Atrix 中尝试，则会抛出异常未知主机 db.tt.

实际上，首先我有像 http://www.db.tt/xyzabc 这样的 url，这是 HTTP url，我打开它，然后得到 例外，在例外情况下，我得到实际的 url包含 file 且为 HTTPS url 的文件例外。我开始下载文件，这是我的代码，对我有用：

public static void fileUrl(String fAddress, String localFileName,
        String destinationDir) {
    OutputStream outStream = null;
    URLConnection uCon = null;

    InputStream is = null;
    try {
        URL url;
        byte[] buf;
        int ByteRead, ByteWritten = 0;
        url = new URL(fAddress);
        outStream = new BufferedOutputStream(new FileOutputStream(
                destinationDir + localFileName));

        try {
            // Here i have "http://www.db.tt/xyzabc"
                       // after i hit url i get exception and in exception that
                       // FileNotFoundException at https://www.dropbox.com/abcxyz
                     // i get actual actual url i parse that exception and 
                     //retrive https://www.dropbox.com/xyzabc(actual url)
                      // but in motorolla atrix instead of that url i get
                     // unknownhost exception "db.tt"




            uCon = url.openConnection();   
        //  uCon.connect();

            is = uCon.getInputStream();
        } catch (Exception e) {
            url = new URL(e.getMessage().substring(
                    e.getMessage().indexOf("https"),
                    e.getMessage().length()));
            outStream = new BufferedOutputStream(new FileOutputStream(
                    destinationDir + localFileName));

            uCon = url.openConnection();
            is = uCon.getInputStream();
        }

        buf = new byte[size];
        while ((ByteRead = is.read(buf)) != -1) {
            outStream.write(buf, 0, ByteRead);
            ByteWritten += ByteRead;
        }
        System.out.println("Downloaded Successfully.");
        System.out.println("File name:\"" + localFileName
                + "\"\nNo ofbytes :" + ByteWritten);
    } catch (Exception e) {
        e.printStackTrace();
    } finally {
        try {
            is.close();
            outStream.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

Answer 1

好的，经过几次尝试，我让它解决了我自己的问题，如果有人遇到同样的问题，这个解决方案将会很有帮助，它需要一些错误处理和根据需要进行修改

在看到 Connection 的类层次结构之后，我发现 HttpsURLConnection 是 HttpURLConnection 的子级，而 HttpURLConnection 是UrlConnection 的子级，因此我使用 HTTPConnection 而不是 UrlConnection，并且由于 HttpsUrlConnection 对于 HttpsUrlConnection 来说是具体的，它解决了我的问题
我继续迭代，直到重定向后获得 Https url

public static void fileUrl(String fAddress, String localFileName,
        String destinationDir) {
    OutputStream outStream = null;
    URLConnection uCon = null;
    HttpURLConnection mHttpCon;

    InputStream is = null;
    try {

        URL url;
        byte[] buf;
        int ByteRead, ByteWritten = 0;
        url = new URL(fAddress);
        outStream = new BufferedOutputStream(new FileOutputStream(
                destinationDir + localFileName));

        try {

            mHttpCon = (HttpURLConnection) url.openConnection();

            while (!url.toString().startsWith("https")) {
                mHttpCon.getResponseCode();
                url = mHttpCon.getURL();
                mHttpCon = (HttpURLConnection) url.openConnection();

            }

            is = mHttpCon.getInputStream();
        } catch (Exception e) {
            e.printStackTrace();
            // url = new URL(e.getMessage().substring(
            // e.getMessage().indexOf("https"),
            // e.getMessage().length()));
            // outStream = new BufferedOutputStream(new FileOutputStream(
            // destinationDir + localFileName));
            //
            // uCon = url.openConnection();
            // is = uCon.getInputStream();
        }

        buf = new byte[size];
        while ((ByteRead = is.read(buf)) != -1) {
            outStream.write(buf, 0, ByteRead);
            ByteWritten += ByteRead;
        }
        System.out.println("Downloaded Successfully.");
        System.out.println("File name:\"" + localFileName
                + "\"\nNo ofbytes :" + ByteWritten);
    } catch (Exception e) {
        e.printStackTrace();
    } finally {
        try {
            is.close();
            outStream.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

public static void fileDownload(String fAddress, String destinationDir) {

    int slashIndex = fAddress.lastIndexOf('/');
    int periodIndex = fAddress.lastIndexOf('.');

    String fileName = fAddress.substring(slashIndex + 1);

    if (periodIndex >= 1 && slashIndex >= 0
            && slashIndex < fAddress.length() - 1) {
        fileUrl(fAddress, fileName, destinationDir);
    } else {
        System.err.println("path or file name.");
    }
}

Answer 2

这个答案在一定程度上是有效的。我有一个类似的解决方案这里

Atrix 上的 Dropbox 短超链接仍然存在问题。它们从 http 重定向到 https，但没有重定向到所需的文件，而是从 Dropbox 内部获取大量 html。