从FTP服务器读取txt文件，并从AsyncTask的返回它 [英] Reading txt file from an ftp server and returning it from AsyncTask

问题描述

我有一个 txt文件在我的 FTP服务器。和所有我想要做的就是读取文件，检索的内容，并通过使用的AsyncTask 保存为一个字符串。当我从logcat的理解，我能够连接 FTP服务器，我可以改变目录。但我不能阅读文本文件的情况下，我不知道如何从我的的AsyncTask 类返回。

而这些是我的codeS：

MainActivity.java

 包com.example.ftpdenemeleri;进口android.os.Bundle;
进口android.support.v7.app.ActionBarActivity;公共类MainActivity扩展ActionBarActivity {@覆盖
保护无效的onCreate（捆绑savedInstanceState）{    super.onCreate（savedInstanceState）;
    的setContentView（R.layout.activity_main）;    FtpAsync任务1 =新FtpAsync（）;
    task1.execute（）;    }
}
 

FtpAsync.java

 包com.example.ftpdenemeleri;进口java.io.BufferedInputStream中;
进口java.io.IOException异常;
进口的java.io.InputStream;进口org.apache.commons.net.ftp.FTPClient;
进口org.apache.commons.net.ftp.FTPCmd;
进口android.os.AsyncTask;公共类FtpAsync扩展的AsyncTask＆LT;太虚，太虚，字符串＆GT; {@覆盖
在preExecute保护无效（）{
   super.on preExecute（）;
}@覆盖
保护字符串doInBackground（虚空...... PARAMS）{
    // TODO自动生成方法存根    FTPClient ftpClient =新FTPClient（）;
    尝试{
        ftpClient.connect（主机名，21）;        的System.out.println（ftpClient.getReplyString（））;
        ftpClient.sendCommand（FTPCmd.USER，用户）;
        的System.out.println（ftpClient.getReplyString（））;
        ftpClient.sendCommand（FTPCmd.PASS，通）;
        的System.out.println（ftpClient.getReplyString（））;
        ftpClient.sendCommand（FTPCmd.CWD，/家庭/网络/ bitirme）;
        InputStream为=新的BufferedInputStream（ftpClient.retrieveFileStream（beaglesays.txt））;
        的System.out.println（输入流已经打开。）;      }赶上（IOException异常前）{
        通信System.err.println（除息）;
    }
    返回null;
}保护无效onPostExecute（）{
        // TODO：检查this.exception
        // TODO：做一些配合饲料
    }
}
 

解决方案

有很多方法可以充分阅读的InputStream为一个字符串。一个最简单的是使用<一个href=\"http://commons.apache.org/proper/commons-io/apidocs/org/apache/commons/io/IOUtils.html#toString%28java.io.InputStream,%20java.nio.charset.Charset%29\"相对=nofollow> IOUtils.toString（） 从的 Apache的百科全书IO 。

因此​​，假设，这些变化将返回从表示字符串doInBackground（）和 onPostExecute接受它（）。

I have a txt file in my ftp server. And all I want to do is reading that file, retrieve the contents and save it as a string by using AsyncTask. As I understand from the logcat, I'm able to connect ftp server and I can change directory. But I cannot read the context of the text file, and I don't know how to return it from the my AsyncTask class.

And these are my codes:

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
    }
}

解决方案

There are many ways to fully read an InputStream into a String. The easiest one would be to use IOUtils.toString() from Apache Commons IO.

So, assuming that, the changes would be to return said string from doInBackground() and receive it in onPostExecute().

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