Getting error with sun.net.ftp.FtpClient by using JDK 1.7

Question

I have developed a project that uses sun.net.ftp.FtpClient class to download a file from an ftp server whil i was using JDK 1.5. Now i have switched to JDK 1.7 and i get the following error.

java: sun.net.ftp.FtpClient is abstract; cannot be instantiated

It seams to me JDK 1.7 does not support FtpClient .

Any suggestions to solve this issue are welcome?

Solution 1

You shouldn't use classes in sun.* - there are no guarantee that they will remain compatible between java-versions.

I would suggest a rewrite to use something like Apache Commons FTP instead. It should be pretty simple to use, so it should be an easy job.

Solution 2

Even though there is truth in that classes in sun.* should be avoided, the answer does not address the error appropriately, besides suggesting an alternative.

I don't have a scope on the context in which you are trying to instantiate sun.net.ftp.FtpClient - but it is still possible to do so.

The class is abstract, so you can't instantiate it. (See §8.1.1.1)

All is not lost though. To get an instance of FtpClient, you can use the static methods from sun.net.ftp.FtpClientProvider that is found in the SDK to do so, like in the example below:

...
final FtpClient ftpClient = FtpClientProvider.provider().createFtpClient();
final InetAddress inetAddress = InetAddress.getByName(ftpUrl.getHost());
final int port = ftpUrl.getPort();
final InetSocketAddress socketAddress = new InetSocketAddress(inetAddress, port);
ftpClient.connect(socketAddress);
ftpClient.login(username, password.toCharArray());
...

There is a bit more work involved, but it allows you to avoid adding a new library with heaps of classes that you don't need - it depends on what you want to do.

Solution 3

There are some changes since 1.7. Such as:

 * before 1.7
 * FtpClient fc=new FtpClient(url,port);
 * fc.login(user, pwd);
 *  fc.binary();
 *  fc.put(remotefilename);
 *  fc.closeServer();
 *  
 * since 1.7
 * FtpClient fc = FtpClient.create(url)
 * fc.login(user, null, pwd);
 * fc.setBinaryType();
 * fc.put(remotefilename,true);
 * fc.close();