android - 我想访问位于 FTP 服务器上的文件并将其显示在我的应用程序中

Question

我想通过提供 ftp 的主机名来访问位于 FTP 服务器上的文件夹中的文件，并将其显示在我使用 android studio 开发的应用程序中。它应该是动态的，也就是说它应该反射(reflect)在我给出了特定 URL 的文件夹内所做的所有更改，也就是说，如果删除或插入某些内容，它应该反射(reflect)在应用程序中。我无法连接到 FTP 服务器，我的应用程序崩溃了。下面是我的应用程序的代码。请查看代码并帮助我。 谢谢。

这是我的 MainActivity.java:-

package com.example.nishant.ftp1;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.Toast;
import android.os.StrictMode;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;

import org.apache.commons.net.PrintCommandListener;
import org.apache.commons.net.ftp.FTP;
import org.apache.commons.net.ftp.FTPClient;
import org.apache.commons.net.ftp.FTPConnectionClosedException;
import org.apache.commons.net.ftp.FTPReply;
import org.apache.commons.net.ftp.FTPSClient;

import java.io.IOException;
import java.io.PrintWriter;


import org.apache.commons.net.ftp.FTPClient;

import java.io.InputStream;
import java.net.SocketException;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        FTPClient ftpClient = new FTPClient();
        try {

            ftpClient.connect("ftp.drivehq.com");
            ftpClient.enterLocalPassiveMode();

            Log.v("ttt", "connected");
            ftpClient.setFileType(FTPClient.ASCII_FILE_TYPE);


            runOnUiThread(new Runnable() {
                @Override
                public void run() {
                    Toast.makeText(MainActivity.this, "done", Toast.LENGTH_SHORT).show();

                }
            });
            ftpClient.disconnect();
            /*Workbook wb = Workbook.getWorkbook(inStream);
            Sheet s = wb.getSheet(0);
            int row = s.getRows();
            int col = s.getColumns();

            for (int i = 0; i < row; i++) {
                for(int c = 0, c< col; c++){
                    Cell z = s.getCell(c, i);
                    String content = z.getContents();
                }
            }*/

        } catch (SocketException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

}

logcat 错误:

01-24 12:45:09.643 7023-7023/com.example.nishant.ftp1 E/Zygote: MountEmulatedStorage()
01-24 12:45:09.643 7023-7023/com.example.nishant.ftp1 E/Zygote: v2
01-24 12:45:09.643 7023-7023/com.example.nishant.ftp1 I/SELinux: Function: selinux_compare_spd_ram , priority [2] , priority version is VE=SEPF_SAMSUNG-SGH-I337_5.0.1-1_0039
01-24 12:45:09.643 7023-7023/com.example.nishant.ftp1 E/SELinux: [DEBUG] get_category: variable seinfo: default sensitivity: NULL, cateogry: NULL
01-24 12:45:09.643 7023-7023/com.example.nishant.ftp1 I/art: Late-enabling -Xcheck:jni
01-24 12:45:09.643 7023-7023/com.example.nishant.ftp1 I/libpersona: KNOX_SDCARD checking this for 10240
01-24 12:45:09.643 7023-7023/com.example.nishant.ftp1 I/libpersona: KNOX_SDCARD not a persona
01-24 12:45:09.773 7023-7023/com.example.nishant.ftp1 D/ResourcesManager: creating new AssetManager and set to /data/app/com.example.nishant.ftp1-1/base.apk
01-24 12:45:10.013 7023-7023/com.example.nishant.ftp1 I/InstantRun: starting instant run server: is main process
01-24 12:45:10.253 7023-7023/com.example.nishant.ftp1 W/art: Before Android 4.1, method android.graphics.PorterDuffColorFilter android.support.graphics.drawable.VectorDrawableCompat.updateTintFilter(android.graphics.PorterDuffColorFilter, android.content.res.ColorStateList, android.graphics.PorterDuff$Mode) would have incorrectly overridden the package-private method in android.graphics.drawable.Drawable
01-24 12:45:10.664 7023-7023/com.example.nishant.ftp1 D/AndroidRuntime: Shutting down VM
01-24 12:45:10.674 7023-7023/com.example.nishant.ftp1 E/AndroidRuntime: FATAL EXCEPTION: main
                                                                        Process: com.example.nishant.ftp1, PID: 7023
                                                                        java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.nishant.ftp1/com.example.nishant.ftp1.MainActivity}: android.os.NetworkOnMainThreadException
                                                                            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2702)
                                                                            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2767)
                                                                            at android.app.ActivityThread.access$900(ActivityThread.java:177)
                                                                            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1449)
                                                                            at android.os.Handler.dispatchMessage(Handler.java:102)
                                                                            at android.os.Looper.loop(Looper.java:145)
                                                                            at android.app.ActivityThread.main(ActivityThread.java:5951)
                                                                            at java.lang.reflect.Method.invoke(Native Method)
                                                                            at java.lang.reflect.Method.invoke(Method.java:372)
                                                                            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1399)
                                                                            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1194)
                                                                         Caused by: android.os.NetworkOnMainThreadException
                                                                            at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1147)
                                                                            at java.net.InetAddress.lookupHostByName(InetAddress.java:418)
                                                                            at java.net.InetAddress.getAllByNameImpl(InetAddress.java:252)
                                                                            at java.net.InetAddress.getByName(InetAddress.java:305)
                                                                            at org.apache.commons.net.SocketClient.connect(SocketClient.java:202)
                                                                            at org.apache.commons.net.SocketClient.connect(SocketClient.java:306)
                                                                            at com.example.nishant.ftp1.MainActivity.onCreate(MainActivity.java:40)
                                                                            at android.app.Activity.performCreate(Activity.java:6289)
                                                                            at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1119)
                                                                            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2655)
                                                                            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2767) 
                                                                            at android.app.ActivityThread.access$900(ActivityThread.java:177) 
                                                                            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1449) 
                                                                            at android.os.Handler.dispatchMessage(Handler.java:102) 
                                                                            at android.os.Looper.loop(Looper.java:145) 
                                                                            at android.app.ActivityThread.main(ActivityThread.java:5951) 
                                                                            at java.lang.reflect.Method.invoke(Native Method) 
                                                                            at java.lang.reflect.Method.invoke(Method.java:372) 
                                                                            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1399) 
                                                                            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1194) 
 01-24 12:50:11.007 7023-7023/com.example.nishant.ftp1 I/Process: Sending signal. PID: 7023 SIG: 9

build.gradle:

apply plugin: 'com.android.application'

android {
    compileSdkVersion 26
    defaultConfig {
        applicationId "com.example.nishant.ftp1"
        minSdkVersion 15
        targetSdkVersion 26
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
}

dependencies {
    implementation fileTree(include: ['*.jar'], dir: 'libs')
    implementation 'com.android.support:appcompat-v7:26.1.0'
    implementation 'com.android.support.constraint:constraint-layout:1.0.2'
    testImplementation 'junit:junit:4.12'
    androidTestImplementation 'com.android.support.test:runner:1.0.1'
    androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.1'
    implementation files('libs/commons-net-3.6.jar')
}

activity_main.xml

Answer 1

您可以使用 Asynctask 类解决问题。你可以在这里找到代码:

FTP connection java