web-dev-qa-db-ja.com

Android-ウェブサーバーからファイルをダウンロードする方法

私のアプリでは、webserverからkmlファイルをダウンロードしています。外部ストレージとインターネットの許可をAndroidマニフェストファイルに設定しました。Androidの初心者です。

MainActivity.Java

package com.example.demo;

import Java.io.DataInputStream;
import Java.io.File;
import Java.io.FileOutputStream;
import Java.io.IOException;
import Java.io.InputStream;
import Java.net.MalformedURLException;
import Java.net.URL;

import Android.app.Activity;
import Android.os.Bundle;
import Android.os.Environment;
import Android.util.Log;
import Android.view.Menu;

public class MainActivity extends Activity {

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

        DownloadFiles();
    }
    public void DownloadFiles(){

            try {
                URL u = new URL("http://www.qwikisoft.com/demo/ashade/20001.kml");
                InputStream is = u.openStream();

                DataInputStream dis = new DataInputStream(is);

                byte[] buffer = new byte[1024];
                int length;

                FileOutputStream fos = new FileOutputStream(new File(Environment.getExternalStorageDirectory() + "/" + "data/test.kml"));
                while ((length = dis.read(buffer))>0) {
                  fos.write(buffer, 0, length);
                }

              } catch (MalformedURLException mue) {
                Log.e("SYNC getUpdate", "malformed url error", mue);
              } catch (IOException ioe) {
                Log.e("SYNC getUpdate", "io error", ioe);
              } catch (SecurityException se) {
                Log.e("SYNC getUpdate", "security error", se);
              }
    }
}

Androidマニフェストファイル

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:Android="http://schemas.Android.com/apk/res/Android"
    package="com.example.demo"
    Android:versionCode="1"
    Android:versionName="1.0" >

    <uses-sdk
        Android:minSdkVersion="8"
        Android:targetSdkVersion="16" />
    <uses-permission Android:name="Android.permission.INTERNET"/>
    <uses-permission Android:name="Android.permission.WRITE_EXTERNAL_STORAGE"/>

    <application
        Android:allowBackup="true"
        Android:icon="@drawable/ic_launcher"
        Android:label="@string/app_name"
        Android:theme="@style/AppTheme" >

        <activity
            Android:name="com.example.demo.MainActivity"
            Android:label="@string/app_name" >
            <intent-filter>
                <action Android:name="Android.intent.action.MAIN" />

                <category Android:name="Android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

Logcatエラー：

FATAL EXCEPTION: main
Java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.demo/com.example.demo.MainActivity}: Android.os.NetworkOnMainThreadException
at Android.app.ActivityThread.performLaunchActivity(ActivityThread.Java:1956)
at Android.app.ActivityThread.handleLaunchActivity(ActivityThread.Java:1981)
at Android.app.ActivityThread.access$600(ActivityThread.Java:123)
at Android.app.ActivityThread$H.handleMessage(ActivityThread.Java:1147)
at Android.os.Handler.dispatchMessage(Handler.Java:99)
at Android.os.Looper.loop(Looper.Java:137)
at Android.app.ActivityThread.main(ActivityThread.Java:4424)
at Java.lang.reflect.Method.invokeNative(Native Method)
at Java.lang.reflect.Method.invoke(Method.Java:511)
at com.Android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.Java:784)
at com.Android.internal.os.ZygoteInit.main(ZygoteInit.Java:551)
at dalvik.system.NativeStart.main(Native Method)
Caused by: Android.os.NetworkOnMainThreadException
at Android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.Java:1099)
at Java.net.InetAddress.lookupHostByName(InetAddress.Java:391)
at Java.net.InetAddress.getAllByNameImpl(InetAddress.Java:242)
at Java.net.InetAddress.getAllByName(InetAddress.Java:220)
at libcore.net.http.HttpConnection.<init>(HttpConnection.Java:71)
at libcore.net.http.HttpConnection.<init>(HttpConnection.Java:50)
at libcore.net.http.HttpConnection$Address.connect(HttpConnection.Java:351)
at libcore.net.http.HttpConnectionPool.get(HttpConnectionPool.Java:86)
at libcore.net.http.HttpConnection.connect(HttpConnection.Java:128)
at libcore.net.http.HttpEngine.openSocketConnection(HttpEngine.Java:308)
at libcore.net.http.HttpEngine.connect(HttpEngine.Java:303)
at libcore.net.http.HttpEngine.sendSocketRequest(HttpEngine.Java:282)
at libcore.net.http.HttpEngine.sendRequest(HttpEngine.Java:232)
at libcore.net.http.HttpURLConnectionImpl.getResponse(HttpURLConnectionImpl.Java:273)
at libcore.net.http.HttpURLConnectionImpl.getInputStream(HttpURLConnectionImpl.Java:168)
at Java.net.URL.openStream(URL.Java:462)
at com.example.demo.MainActivity.DownloadFiles(MainActivity.Java:30)
at com.example.demo.MainActivity.onCreate(MainActivity.Java:24)
at Android.app.Activity.performCreate(Activity.Java:4465)
at Android.app.Instrumentation.callActivityOnCreate(Instrumentation.Java:1049)
at Android.app.ActivityThread.performLaunchActivity(ActivityThread.Java:1920)

編集

package com.example.demo;

import Java.io.BufferedInputStream;
import Java.io.FileOutputStream;
import Java.io.InputStream;
import Java.io.OutputStream;
import Java.net.URL;
import Java.net.URLConnection;

import Android.app.Activity;
import Android.app.Dialog;
import Android.app.ProgressDialog;
import Android.os.AsyncTask;
import Android.os.Bundle;
import Android.os.Environment;
import Android.util.Log;

public class MainActivity extends Activity {

    private ProgressDialog pDialog;
    public static final int progress_bar_type = 0;

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

        new DownloadFileFromURL().execute("http://www.qwikisoft.com/demo/ashade/20001.kml");

    }

    @Override
    protected Dialog onCreateDialog(int id) {
        switch (id) {
        case progress_bar_type: // we set this to 0
            pDialog = new ProgressDialog(this);
            pDialog.setMessage("Downloading file. Please wait...");
            pDialog.setIndeterminate(false);
            pDialog.setMax(100);
            pDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
            pDialog.setCancelable(true);
            pDialog.show();
            return pDialog;
        default:
            return null;
        }
    }


    class DownloadFileFromURL extends AsyncTask<String, String, String> {

        /**
         * Before starting background thread Show Progress Bar Dialog
         * */
        @Override
        protected void onPreExecute() {
            super.onPreExecute();
            showDialog(progress_bar_type);
        }

        /**
         * Downloading file in background thread
         * */
        @Override
        protected String doInBackground(String... f_url) {
            int count;
            try {
                URL url = new URL(f_url[0]);
                URLConnection conection = url.openConnection();
                conection.connect();

                // this will be useful so that you can show a tipical 0-100%
                // progress bar
                int lenghtOfFile = conection.getContentLength();

                // download the file
                InputStream input = new BufferedInputStream(url.openStream(),
                        8192);

                // Output stream
                OutputStream output = new FileOutputStream(Environment
                        .getExternalStorageDirectory().toString()
                        + "/data/downloadedfile.kml");

                byte data[] = new byte[1024];

                long total = 0;

                while ((count = input.read(data)) != -1) {
                    total += count;
                    // publishing the progress....
                    // After this onProgressUpdate will be called
                    publishProgress("" + (int) ((total * 100) / lenghtOfFile));

                    // writing data to file
                    output.write(data, 0, count);
                }

                // flushing output
                output.flush();

                // closing streams
                output.close();
                input.close();

            } catch (Exception e) {
                Log.e("Error: ", e.getMessage());
            }

            return null;
        }

        /**
         * Updating progress bar
         * */
        protected void onProgressUpdate(String... progress) {
            // setting progress percentage
            pDialog.setProgress(Integer.parseInt(progress[0]));
        }

        /**
         * After completing background task Dismiss the progress dialog
         * **/
        @Override
        protected void onPostExecute(String file_url) {
            // dismiss the dialog after the file was downloaded
            dismissDialog(progress_bar_type);

        }
    }
}

エミュレータでこのコードを実行すると、コードはまだ機能しません。ファイルはダウンロードされません。

androidwebserverkml
45
Iam4fun

非同期タスク を使用します。 （4.0で動作しない場合は追加します

StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
StrictMode.setThreadPolicy(policy);

）

ファイルをダウンロードするときに呼び出します：new DownloadFileFromURL().execute(file_url);

public class MainActivity extends Activity {

    // Progress Dialog
    private ProgressDialog pDialog;
    public static final int progress_bar_type = 0;

    // File url to download
    private static String file_url = "http://www.qwikisoft.com/demo/ashade/20001.kml";

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

        new DownloadFileFromURL().execute(file_url);

    }

    /**
     * Showing Dialog
     * */

    @Override
    protected Dialog onCreateDialog(int id) {
        switch (id) {
        case progress_bar_type: // we set this to 0
            pDialog = new ProgressDialog(this);
            pDialog.setMessage("Downloading file. Please wait...");
            pDialog.setIndeterminate(false);
            pDialog.setMax(100);
            pDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
            pDialog.setCancelable(true);
            pDialog.show();
            return pDialog;
        default:
            return null;
        }
    }

    /**
     * Background Async Task to download file
     * */
    class DownloadFileFromURL extends AsyncTask<String, String, String> {

        /**
         * Before starting background thread Show Progress Bar Dialog
         * */
        @Override
        protected void onPreExecute() {
            super.onPreExecute();
            showDialog(progress_bar_type);
        }

        /**
         * Downloading file in background thread
         * */
        @Override
        protected String doInBackground(String... f_url) {
            int count;
            try {
                URL url = new URL(f_url[0]);
                URLConnection conection = url.openConnection();
                conection.connect();

                // this will be useful so that you can show a tipical 0-100%
                // progress bar
                int lenghtOfFile = conection.getContentLength();

                // download the file
                InputStream input = new BufferedInputStream(url.openStream(),
                        8192);

                // Output stream
                OutputStream output = new FileOutputStream(Environment
                        .getExternalStorageDirectory().toString()
                        + "/2011.kml");

                byte data[] = new byte[1024];

                long total = 0;

                while ((count = input.read(data)) != -1) {
                    total += count;
                    // publishing the progress....
                    // After this onProgressUpdate will be called
                    publishProgress("" + (int) ((total * 100) / lenghtOfFile));

                    // writing data to file
                    output.write(data, 0, count);
                }

                // flushing output
                output.flush();

                // closing streams
                output.close();
                input.close();

            } catch (Exception e) {
                Log.e("Error: ", e.getMessage());
            }

            return null;
        }

        /**
         * Updating progress bar
         * */
        protected void onProgressUpdate(String... progress) {
            // setting progress percentage
            pDialog.setProgress(Integer.parseInt(progress[0]));
        }

        /**
         * After completing background task Dismiss the progress dialog
         * **/
        @Override
        protected void onPostExecute(String file_url) {
            // dismiss the dialog after the file was downloaded
            dismissDialog(progress_bar_type);

        }

    }
}
70
Nirav Ranpara

Android DownloadManager を使用することをお勧めします

DownloadManager downloadmanager = (DownloadManager) getSystemService(Context.DOWNLOAD_SERVICE);
Uri uri = Uri.parse("http://www.example.com/myfile.mp3");

DownloadManager.Request request = new DownloadManager.Request(uri);
request.setTitle("My File");
request.setDescription("Downloading");
request.setNotificationVisibility(DownloadManager.Request.VISIBILITY_VISIBLE_NOTIFY_COMPLETED);
request.setVisibleInDownloadsUi(false);
request.setDestinationUri(Uri.parse("file://" + folderName + "/myfile.mp3"));

downloadmanager.enqueue(request);
19
Awsom3D

シンプルなコトリンバージョン

fun download(link: String, path: String) {
    URL(link).openStream().use { input ->
        FileOutputStream(File(path)).use { output ->
            input.copyTo(output)
        }
    }
}

編集

または拡張子として

fun String.saveTo(path: String) {
    URL(link).openStream().use { input ->
        FileOutputStream(File(path)).use { output ->
            input.copyTo(output)
        }
    }
}

// ...

"http://example.site/document".saveTo("some/path/file")
18
Vlad

メインスレッドでネットワーク操作を実行するのは悪い習慣です。そのため、NetworkOnMainThreadExceptionが表示されます。ポリシーによって防止されています。テストのために本当にそれを行う必要がある場合は、OnCreateに以下を追加します。

 StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
 StrictMode.setThreadPolicy(policy);

これは非常に悪い習慣であり、ネットワークコードをAsyncTaskまたはThreadに移動するのが理想的です。

10
tristan2468

Mr.Iam4funあなたのコードの答えはこちら..あなたはスレッドを使用します...

   findViewById(R.id.download).setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

            new Thread(new Runnable() {
                public void run() {
                    DownloadFiles();
                }
            }).start();

その後..

 public void DownloadFiles(){

        try {
            URL u = new URL("http://www.qwikisoft.com/demo/ashade/20001.kml");
            InputStream is = u.openStream();

            DataInputStream dis = new DataInputStream(is);

            byte[] buffer = new byte[1024];
            int length;

            FileOutputStream fos = new FileOutputStream(new File(Environment.getExternalStorageDirectory() + "/" + "data/test.kml"));
            while ((length = dis.read(buffer))>0) {
              fos.write(buffer, 0, length);
            }

          } catch (MalformedURLException mue) {
            Log.e("SYNC getUpdate", "malformed url error", mue);
          } catch (IOException ioe) {
            Log.e("SYNC getUpdate", "io error", ioe);
          } catch (SecurityException se) {
            Log.e("SYNC getUpdate", "security error", se);
          }
}
}

もちろん動作します。

1
Mathan Chinna

AsyncTaskを使用し、

ダウンロードファイルのコードをdoinbackgroundに入れます。

Androidは、ANR（アプリケーションが応答しない）エラーを回避するために、メインスレッドで重いタスクを実行することを許可しなくなりました

0
DeltaCap019

AsyncTaskの使用とは別に、操作をrunnable-

Runnable r=new Runnable()
{

public void run()
{
///-------network operation code
}
};

//--------call r in this way--
Thread t=new Thread(r);`enter code here`
t.start();

Also put the UI work in a haldler..such as updating a textview etc..
0
user6823720

APIレベル11またはHoneycombからメインスレッドでネットワーク操作を行うことは禁止されています。 threadまたはasynctaskを使用します。詳細については、 https://developer.Android.com/reference/Android/os/NetworkOnMainThreadException.html をご覧ください。

0
Bek

これらのコードをスレッドまたはAsyncTaskで実行します。同じ_url（getContentLength（）の1回、openStream（）の1回）の重複呼び出しを避けるために、ApacheのIOUtils.toByteArrayを使用します。

void downloadFile(String _url, String _name) {
    try {
        URL u = new URL(_url);
        DataInputStream stream = new DataInputStream(u.openStream());
        byte[] buffer = IOUtils.toByteArray(stream);
        FileOutputStream fos = mContext.openFileOutput(_name, Context.MODE_PRIVATE);
        fos.write(buffer);
        fos.flush();
        fos.close();
    } catch (FileNotFoundException e) {
        e.printStackTrace();
        return;
    } catch (IOException e) {
        e.printStackTrace();
        return;
    }
}
0
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