java - 从 FTP 服务器读取文件，但 InputStream 始终为空

Question

我想读取目录中的文件。我要添加: List<String> nomi = new ArrayList<String>();文件 Nomi.txt 的线串。

通过调试，我可以正确查看链接(001.jpg 002.jpg 003.jpg)和 ft(Nomi.txt)中的文件，但在流中我始终为空；

InputStream stream = f.retrieveFileStream(/*url_ftp + "/photo/"+ft*/ft);

我的完整代码是这样的:

private static abstract class GetLinksTask extends AsyncTask<String, Void, List<String>> {

    protected List<String> doInBackground(String... urls) {
        List<String> links = new ArrayList<String>();
        String ft=null;
        BufferedReader reader = null;
        List<String> nomi = new ArrayList<String>();
        FTPClient f = new FTPClient();

        try {
            int reply;
            f.connect(url_ftp);
            f.login(username,password );
            reply = f.getReplyCode();
            if (!FTPReply.isPositiveCompletion(reply)) {
                f.disconnect();
                System.err.println("FTP server refused connection.");
            }
            FTPListParseEngine engine = f.initiateListParsing("photo");

            while (engine.hasNext()) {
                FTPFile[] files = engine.getNext(25);  // "page size" you want
                //FTPFile[] files = engine.getFiles(filter);
                for (FTPFile file : files) {   
                    if(file.getName().substring(file.getName().length()-3,file.getName().length()).equals("jpg")){
                        System.out.println(file.getName());
                        links.add(file.getName());
                    }else{
                        ft=file.getName();
                        InputStream stream = f.retrieveFileStream(/*url_ftp + "/photo/"+ft*/ft);
                        reader = new BufferedReader(new InputStreamReader(stream, "UTF-8"));
                        //nomi.add(reader.readLine());                                 
                    }
                    System.out.println(file.getName());
                }
                //names=nomi;
            }
        }catch (IOException e) {
            e.printStackTrace();
        }finally {
            if (reader != null)
                try {
                    reader.close();
                }catch (IOException logOrIgnore) {
            }
        }

        return links;
    }

    protected abstract void postExecute(List<String> links);

    protected void onPostExecute(List<String> lists) {
        postExecute(lists);
    }

}

一些提示？谢谢

Answer 1

仅仅创建一个Reader是不够的

reader = new BufferedReader(new InputStreamReader(stream, "UTF-8"));

并关闭它:

reader.close();

介于两者之间的某个地方，您实际上必须读取数据:

String line;
while( (line = reader.readLine()) != null ){
    nomi.add( line );
}