pdf没有使用下载管理器在前棒棒糖设备中下载

时间:2016-10-12 11:06:43

标签: android pdf android-download-manager

我正在尝试使用DownloadManager下载pdf。

我在链接中传递参数,并从生成并下载到设备的服务器pdf文件中传递参数。所以我的下载链接会是这样的

  

http://example.com/gen.php?data={......}

我的代码:

final Request request = new Request(Uri.parse(fromUrl));
request.setMimeType("application/pdf");
request.setNotificationVisibility(Request.VISIBILITY_VISIBLE_NOTIFY_COMPLETED);
request.setDestinationInExternalPublicDir(path, "ELALA_MANIFEST_" + System.currentTimeMillis() + ".pdf");

final DownloadManager dm = (DownloadManager) context
        .getSystemService(Context.DOWNLOAD_SERVICE);
try {
    try {
        dm.enqueue(request);
    } catch (SecurityException e) {
        request.setNotificationVisibility(Request.VISIBILITY_VISIBLE);
        Log.e("Error", e.toString());
        dm.enqueue(request);
    }

}
// if the download manager app has been disabled on the device
catch (IllegalArgumentException e) {
    openAppSettings(context,
            AdvancedWebView.PACKAGE_NAME_DOWNLOAD_MANAGER);
}

在api等级21(棒棒糖)及以上的设备中正常工作。但在较低版本pdf没有下载。和通知弹出类似,

<untitled> download unsuccessful

我知道这与setMimeType有关,但不知道是什么。

任何帮助将不胜感激。

1 个答案:

答案 0 :(得分:1)

当你得到colnames(dataFrame) <- c("firstCol", "secondCol") 时,通常意味着你的网址不正确或空或空。首先请确保网址没问题。

使用DownloadManager运行4.4(pre-lolipop)中的小例子。

<untitled> download unsuccessful

它使用权限:

import android.app.DownloadManager;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.net.Uri;
import android.os.Bundle;
import android.os.Environment;
import android.support.v7.app.AppCompatActivity;
import android.text.TextUtils;
import android.util.Log;
import android.view.View;

import java.io.File;

public class MainActivity extends AppCompatActivity {

    private DownloadManager dm;
    private String url;

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

        dm = (DownloadManager) getSystemService(DOWNLOAD_SERVICE);
        url = "https://collegereadiness.collegeboard.org/pdf/psat-nmsqt-practice-test-1.pdf";

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

                if (TextUtils.isEmpty(url)) {
                    throw new IllegalArgumentException("url cannot be empty or null");
                }

                DownloadManager.Request request = new DownloadManager.Request(Uri.parse(url));
                request.setNotificationVisibility(DownloadManager.Request.VISIBILITY_VISIBLE_NOTIFY_COMPLETED);

                if (isExternalStorageWritable()) {
                    String uriString = v.getContext().getExternalFilesDir(null) + "";
                    File file = new File(uriString, Uri.parse(url).getLastPathSegment());
                    Uri destinationUri = Uri.fromFile(file);
                    request.setDestinationUri(destinationUri);
                    dm.enqueue(request);
                }
            }
        });

        registerReceiver(receiver, new IntentFilter(DownloadManager.ACTION_DOWNLOAD_COMPLETE));
    }

    private BroadcastReceiver receiver = new BroadcastReceiver() {
        @Override
        public void onReceive(Context context, Intent intent) {
            String action = intent.getAction();
            if (DownloadManager.ACTION_DOWNLOAD_COMPLETE.equals(action)) {
                Log.d(TAG, "onReceive() returned: " + action);
                // TODO: 2016-10-12  
            } else if (DownloadManager.ACTION_NOTIFICATION_CLICKED.equals(action)) {
                Log.d(TAG, "onReceive() returned: " + action);
                // TODO: 2016-10-12  
            }
        }
    };

    private static final String TAG = "MainActivity";

    //...

    public boolean isExternalStorageWritable() {
        String state = Environment.getExternalStorageState();
        return Environment.MEDIA_MOUNTED.equals(state);
    }

    public boolean isExternalStorageReadable() {
        String state = Environment.getExternalStorageState();
        return Environment.MEDIA_MOUNTED.equals(state) ||
                Environment.MEDIA_MOUNTED_READ_ONLY.equals(state);
    }
}

处理所有条件非常重要。也可以尝试使用app目录,而不是乱搞你的SD卡。此示例将下载的文件保存在 <uses-permission android:name="android.permission.INTERNET"/> <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/> <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/> 。以前我检查是否已经安装了SD卡,以及我是否可以在目录上写入。

样品:

enter image description here

好的,如果标题有&#34; Content-Disposition`字段,这是我的解析文件名的示例。你说它是在你的服务器上,所以你将能够做到这一点:)

/sdcard/Android/data/{your app package name}/files/