Question

我的txt file中有一个ftp server。我想要做的就是读取该文件，检索内容并使用AsyncTask将其保存为字符串。据我所知，从logcat，我能够连接ftp server，我可以更改目录。但我无法阅读文本文件的上下文，我不知道如何从我的AsyncTask类返回它。

这些是我的代码：

MainActivity.java

package com.example.ftpdenemeleri;

import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;

public class MainActivity extends ActionBarActivity {

@Override
protected void onCreate(Bundle savedInstanceState) {

    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    FtpAsync task1 = new FtpAsync();
    task1.execute();

    }
}

FtpAsync.java

package com.example.ftpdenemeleri;

import java.io.BufferedInputStream;
import java.io.IOException;
import java.io.InputStream;

import org.apache.commons.net.ftp.FTPClient;
import org.apache.commons.net.ftp.FTPCmd;
import android.os.AsyncTask;

public class FtpAsync extends AsyncTask <Void, Void, String>{

@Override
protected void onPreExecute() {
   super.onPreExecute();      
}

@Override
protected String doInBackground(Void... params) {
    // TODO Auto-generated method stub

    FTPClient ftpClient = new FTPClient();
    try {
        ftpClient.connect("hostname", 21);

        System.out.println(ftpClient.getReplyString());
        ftpClient.sendCommand(FTPCmd.USER, "user");
        System.out.println(ftpClient.getReplyString());
        ftpClient.sendCommand(FTPCmd.PASS, "pass");
        System.out.println(ftpClient.getReplyString());
        ftpClient.sendCommand(FTPCmd.CWD, "/home/www/bitirme");
        InputStream is = new      BufferedInputStream(ftpClient.retrieveFileStream("beaglesays.txt")); 
        System.out.println("Input Stream has opened.");

      } catch (IOException ex) {
        System.err.println(ex);
    }
    return null; 
}

protected void onPostExecute() {
        // TODO: check this.exception 
        // TODO: do something with the feed
    }
}

Answer 1

尝试清楚地理解AsyncTask。一些事情：（1）类似的问题：Howto do a simple ftp get file on Android （2）一旦你在doInBackground（）中获得内容 - 将内容返回为String（目前你返回null）。（3）在onPostExecute（String result）中添加参数，这将是文件的内容。

Answer 2

有很多方法可以将InputStream完全读入String。最简单的方法是使用IOUtils.toString()中的Apache Commons IO。

因此，假设这样做，更改将是从doInBackground()返回所述字符串并在onPostExecute()中接收。

Answer 3

您的代码必须如下：

 package com.example.ftpdenemeleri;

import java.io.BufferedInputStream;
import java.io.IOException;
import java.io.InputStream;

import org.apache.commons.net.ftp.FTPClient;
import org.apache.commons.net.ftp.FTPCmd;
import android.os.AsyncTask;

public class FtpAsync extends AsyncTask <Void, Void, String>{

@Override
protected void onPreExecute() {
super.onPreExecute();      
}

@Override
protected String doInBackground(Void... params) {
// TODO Auto-generated method stub

FTPClient ftpClient = new FTPClient();
try {
    ftpClient.connect("hostname", 21);

    System.out.println(ftpClient.getReplyString());
    ftpClient.sendCommand(FTPCmd.USER, "user");
    System.out.println(ftpClient.getReplyString());
    ftpClient.sendCommand(FTPCmd.PASS, "pass");
    System.out.println(ftpClient.getReplyString());
    ftpClient.sendCommand(FTPCmd.CWD, "/home/www/bitirme");
    InputStream is = new           BufferedInputStream(ftpClient.retrieveFileStream("beaglesays.txt")); 
    System.out.println("Input Stream has opened.");

Scanner s = new Scanner(is).useDelimiter("\\A"); // Convert your stream into string
        return s.hasNext() ? s.next() : ""; //send the string to onPostExecute()


  } catch (IOException ex) {
    System.err.println(ex);
}
return null; 
}


protected void onPostExecute(String result) {
    // TODO: check this.exception 
    // TODO: do something with the feed
Log.i("Result : ",result);
    }
}

从ftp服务器读取文本文件并从AsyncTask返回

3 个答案: