这个问题在这里已有答案:
你好,
对于一个项目,我必须在FTP服务器上连接一个Android设备(端口:21)。
经过研究,我找到了一个允许Android设备和FTP服务器之间连接的软件包。
所以我在Internet上关注了一个示例find,并且我在我的设备的同一网络中的Raspberry Pi中创建了我的FTP服务器。
但我的应用程序无法连接到它。如该应用程序的屏幕截图所示:
ftp://
的IP地址之前,但没有成功。package com.example.erwan.ftplearn;
import android.util.Log;
import org.apache.commons.net.ftp.FTP;
import org.apache.commons.net.ftp.FTPClient;
import org.apache.commons.net.ftp.FTPReply;
import org.apache.commons.net.ftp.FTPSClient;
import java.io.IOException;
import java.net.InetAddress;
public class FTPModel {
public FTPClient mFTPClient = null;
public boolean connect(String host, String username, String password, int port)
{
try {
mFTPClient = new FTPClient();
// connecting to the host
mFTPClient.connect(host, port);
// now check the reply code, if positive mean connection success
boolean status = mFTPClient.login(username, password);
mFTPClient.setFileType(FTP.BINARY_FILE_TYPE);
mFTPClient.enterLocalPassiveMode();
return status;
} catch (Exception e) {
Log.i("testConnection", "Error: could not connect to host " + host);
}
return false;
}
}
package com.example.erwan.ftplearn;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.widget.TextView;
import com.adeel.library.easyFTP;
public class MainActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
FTPModel mymodel = new FTPModel();
boolean co = mymodel.connect("192.168.1.25", "xxxxx", "xxxxx", 21);
TextView statut = findViewById(R.id.connexionstatut);
if(co)
{
statut.setText("Connecter !");
}
else
{
statut.setText("Erreur de connexion !");
}
}
}
2019-04-06 19:26:31.876 16869-16869/? I/testConnection: Error: could not connect to host 192.168.1.25
Caused by: android.os.NetworkOnMainThreadException
at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1460)
at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:356)
at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:201)
at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:183)
at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:356)
at java.net.Socket.connect(Socket.java:616)
at org.apache.commons.net.SocketClient.connect(SocketClient.java:182)
at org.apache.commons.net.SocketClient.connect(SocketClient.java:203)
at com.example.erwan.ftplearn.FTPModel.connect(FTPModel.java:21)
at com.example.erwan.ftplearn.MainActivity.onCreate(MainActivity.java:22)
at android.app.Activity.performCreate(Activity.java:7383)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1218)
我认为,这个错误在这里,因为FTP服务器的连接必须与另一个线程,但我不知道如何使它。
我发现了问题! FTP服务器上的连接必须在异步任务中进行!
FTPClient不喜欢在主线程中工作,所以我们必须在另一个线程中工作。
package com.example.erwan.ftplearn;
import android.os.AsyncTask;
import android.util.Log;
import org.apache.commons.net.ftp.FTP;
import org.apache.commons.net.ftp.FTPClient;
import org.apache.commons.net.ftp.FTPReply;
import org.apache.commons.net.ftp.FTPSClient;
import java.io.IOException;
import java.net.InetAddress;
public class FTPModel {
public FTPClient mFTPClient = null;
public boolean connect(String host, String username, String password, int port)
{
try
{
return new asyncConnexion(host, username, password, port).execute().get();
}
catch (Exception e)
{
return false;
}
}
public class asyncConnexion extends AsyncTask<Void, Void, Boolean>
{
private String host;
private String username;
private String password;
private int port;
asyncConnexion(String host, String username, String password, int port)
{
this.host = host;
this.password = password;
this.port = port;
this.username = username;
}
@Override
protected Boolean doInBackground(Void... voids) {
try {
mFTPClient = new FTPClient();
// connecting to the host
mFTPClient.connect(host, port);
// now check the reply code, if positive mean connection success
boolean status = mFTPClient.login(username, password);
mFTPClient.setFileType(FTP.BINARY_FILE_TYPE);
mFTPClient.enterLocalPassiveMode();
return status;
} catch (Exception e) {
Log.i("testConnection", "Error: could not connect to host " + host);
e.printStackTrace();
}
return false;
}
}
}