Android开发(22)使用DownloadManager下载文件

张云飞Vir

发布于 2020-03-16 15:14:34

2.5K0

发布于 2020-03-16 15:14:34

文章被收录于专栏：写代码和思考

概述

使用DownloadManager 是个很好用的下载方式。它会出现在任务栏，指示当前的下载位置。它使用广播来接收完成消息，点击任务事件的交互。

实现步骤

1.添加权限

    <uses-permission android:name="android.permission.INTERNET" />
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
    
    <permission android:name="android.permission.ACCESS_DOWNLOAD_MANAGER" />

2.在页面里初始化

  DownloadManager downloadManager;
  
  // 过SystemService 以获取 DownloadManager
         downloadManager = (DownloadManager) getSystemService(DOWNLOAD_SERVICE);

3.启动下载

    Request request = new Request(
    Uri.parse("http://192.168.3.123:8080/androidautoupdate/apks/2.zip"));
    
    request.setAllowedNetworkTypes(
    DownloadManager.Request.NETWORK_MOBILE
    | DownloadManager.Request.NETWORK_WIFI)
    .setAllowedOverRoaming(false) // 缺省是true
    .setTitle("更新") // 用于信息查看
    .setDescription("下载apk") // 用于信息查看
    .setDestinationInExternalPublicDir(
    Environment.DIRECTORY_DOWNLOADS, "2.zip");
    mDownloadId = downloadManager.enqueue(request); // 加入下载队列
    
    startQuery(mDownloadId);

4.移除（停止）下载

private int removeDownload(long downloadId) {
    return downloadManager.remove(downloadId);
}

5.监听下载的完成

@Override
protected void onPause() {
    stopQuery();
    this.unregisterReceiver(receiver);

    super.onPause();
}

@Override
protected void onResume() {
    IntentFilter filter = new IntentFilter(
            DownloadManager.ACTION_DOWNLOAD_COMPLETE);
    this.registerReceiver(receiver, filter);

    IntentFilter filter22 = new IntentFilter(
            DownloadManager.ACTION_NOTIFICATION_CLICKED);
    this.registerReceiver(receiver2, filter22);

    startQuery(mDownloadId);
    super.onResume();
}

// 监听下载结束，启用BroadcastReceiver
BroadcastReceiver receiver = new BroadcastReceiver() {
    @Override
    public void onReceive(Context context, Intent intent) {

        DownloadManager dm = (DownloadManager) getSystemService(DOWNLOAD_SERVICE);
        String action = intent.getAction();
        if (DownloadManager.ACTION_DOWNLOAD_COMPLETE.equals(action)) {

            long downloadId = intent.getLongExtra(
                    DownloadManager.EXTRA_DOWNLOAD_ID, 0);
            // 查询
            Query query = new Query();
            query.setFilterById(downloadId);
            Cursor c = dm.query(query);
            if (c.moveToFirst()) {
                int columnIndex = c
                        .getColumnIndex(DownloadManager.COLUMN_STATUS);
                if (DownloadManager.STATUS_SUCCESSFUL == c
                        .getInt(columnIndex)) {

                    String uriString = c
                            .getString(c
                                    .getColumnIndex(DownloadManager.COLUMN_LOCAL_URI));

                    //removeDownload(downloadId);
                    Toast.makeText(MainActivity.this,
                            "get file complete: " + uriString, 0).show();
                    // Uri.parse(uriString);
                }
            }// endif

        }// endif

    }// onReceive
};// end class receiver

6.在下载过程中，查看状态

class QueryRunnable implements Runnable {
    public long DownID;

    @Override
    public void run() {
        queryState(DownID);
        handler.postDelayed(runnable, step);
    }
};

private void startQuery(long downloadId) {
    if (downloadId != 0) {
        runnable.DownID = downloadId;
        handler.postDelayed(runnable, step);
    }

};

private void stopQuery() {
    handler.removeCallbacks(runnable);
}

private void queryState(long downID) {
    // 关键：通过ID向下载管理查询下载情况，返回一个cursor
    Cursor c = downloadManager.query(new DownloadManager.Query()
            .setFilterById(downID));
    if (c == null) {
        Toast.makeText(this, "Download not found!", Toast.LENGTH_LONG)
                .show();
    } else { // 以下是从游标中进行信息提取
        if(!c.moveToFirst()){
            c.close();
            return;
        }
        Log.d(TAG,
                "Column_id : "
                        + c.getLong(c
                                .getColumnIndex(DownloadManager.COLUMN_ID)));
        Log.d(TAG,
                "Column_bytes_downloaded so far : "
                        + c.getLong(c
                                .getColumnIndex(DownloadManager.COLUMN_BYTES_DOWNLOADED_SO_FAR)));
        Log.d(TAG,
                "Column last modified timestamp : "
                        + c.getLong(c
                                .getColumnIndex(DownloadManager.COLUMN_LAST_MODIFIED_TIMESTAMP)));
        Log.d(TAG,
                "Column local uri : "
                        + c.getString(c
                                .getColumnIndex(DownloadManager.COLUMN_LOCAL_URI)));
        Log.d(TAG,
                "Column statue : "
                        + c.getInt(c
                                .getColumnIndex(DownloadManager.COLUMN_STATUS)));
        Log.d(TAG,
                "Column reason : "
                        + c.getInt(c
                                .getColumnIndex(DownloadManager.COLUMN_REASON)));

        int st = c.getInt(c.getColumnIndex(DownloadManager.COLUMN_STATUS));
        Toast.makeText(this, statusMessage(st), Toast.LENGTH_LONG).show();
        //Log.i(TAG, statusMessage(st));
        
        c.close();
    }
}

private String statusMessage(int st) {
    switch (st) {
    case DownloadManager.STATUS_FAILED:
        return "Download failed";
    case DownloadManager.STATUS_PAUSED:
        return "Download paused";
    case DownloadManager.STATUS_PENDING:
        return "Download pending";
    case DownloadManager.STATUS_RUNNING:
        return "Download in progress!";
    case DownloadManager.STATUS_SUCCESSFUL:
        return "Download finished";
    default:
        return "Unknown Information";
    }
}

完整代码

    package example.downloaddemo;
    
    import java.io.File;
    
    import android.net.Uri;
    import android.os.Bundle;
    import android.os.Environment;
    import android.os.Handler;
    import android.os.Message;
    import android.app.Activity;
    import android.app.DownloadManager;
    import android.app.DownloadManager.Query;
    import android.app.DownloadManager.Request;
    import android.content.BroadcastReceiver;
    import android.content.Context;
    import android.content.Intent;
    import android.content.IntentFilter;
    import android.database.Cursor;
    import android.util.Log;
    import android.view.Menu;
    import android.view.View;
    import android.widget.Toast;
    
    /**
     * 参考：http://blog.csdn.net/flowingflying/article/details/6925683
     * @author yunfei
     *
     */
    public class MainActivity extends Activity {
        private static final String TAG = "PDWY";
        // an ID for the download, unique across the system. This ID is used to make
        // future calls related to this download.
        long mDownloadId;
        DownloadManager downloadManager;
    
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
            // 过SystemService 以获取 DownloadManager
            downloadManager = (DownloadManager) getSystemService(DOWNLOAD_SERVICE);
    
        }
    
        @Override
        protected void onPause() {
            stopQuery();
            this.unregisterReceiver(receiver);
    
            super.onPause();
        }
    
        @Override
        protected void onResume() {
            IntentFilter filter = new IntentFilter(
                    DownloadManager.ACTION_DOWNLOAD_COMPLETE);
            this.registerReceiver(receiver, filter);
    
            IntentFilter filter22 = new IntentFilter(
                    DownloadManager.ACTION_NOTIFICATION_CLICKED);
            this.registerReceiver(receiver2, filter22);
    
            startQuery(mDownloadId);
            super.onResume();
        }
    
        @Override
        public boolean onCreateOptionsMenu(Menu menu) {
            // Inflate the menu; this adds items to the action bar if it is present.
            getMenuInflater().inflate(R.menu.activity_main, menu);
            return true;
        }
    
        public void lookDownload() {
            startActivity(new Intent(DownloadManager.ACTION_VIEW_DOWNLOADS));
        }
    
        public void onClick(View view) {
            int id = view.getId();
            if (id == R.id.start) {
                Request request = new Request(
                        Uri.parse("http://192.168.3.123:8080/androidautoupdate/apks/2.zip"));
    
                request.setAllowedNetworkTypes(
                        DownloadManager.Request.NETWORK_MOBILE
                                | DownloadManager.Request.NETWORK_WIFI)
                        .setAllowedOverRoaming(false) // 缺省是true
                        .setTitle("更新") // 用于信息查看
                        .setDescription("下载apk") // 用于信息查看
                        .setDestinationInExternalPublicDir(
                                Environment.DIRECTORY_DOWNLOADS, "2.zip");
                mDownloadId = downloadManager.enqueue(request); // 加入下载队列
    
                startQuery(mDownloadId);
            }
            if (id == R.id.stop) {
                stopQuery();
                removeDownload(mDownloadId);
            }
            if (id == R.id.look) {
                lookDownload();
            }
        }
    
        private int removeDownload(long downloadId) {
            return downloadManager.remove(downloadId);
        }
    
        Handler handler = new Handler() {
            @Override
            public void handleMessage(Message msg) {
                // TODO Auto-generated method stub
                super.handleMessage(msg);
            }
    
        };
    
        int step = 1000;
        QueryRunnable runnable = new QueryRunnable();
    
        class QueryRunnable implements Runnable {
            public long DownID;
    
            @Override
            public void run() {
                queryState(DownID);
                handler.postDelayed(runnable, step);
            }
        };
    
        private void startQuery(long downloadId) {
            if (downloadId != 0) {
                runnable.DownID = downloadId;
                handler.postDelayed(runnable, step);
            }
    
        };
    
        private void stopQuery() {
            handler.removeCallbacks(runnable);
        }
    
        private void queryState(long downID) {
            // 关键：通过ID向下载管理查询下载情况，返回一个cursor
            Cursor c = downloadManager.query(new DownloadManager.Query()
                    .setFilterById(downID));
            if (c == null) {
                Toast.makeText(this, "Download not found!", Toast.LENGTH_LONG)
                        .show();
            } else { // 以下是从游标中进行信息提取
                if(!c.moveToFirst()){
                    c.close();
                    return;
                }
                Log.d(TAG,
                        "Column_id : "
                                + c.getLong(c
                                        .getColumnIndex(DownloadManager.COLUMN_ID)));
                Log.d(TAG,
                        "Column_bytes_downloaded so far : "
                                + c.getLong(c
                                        .getColumnIndex(DownloadManager.COLUMN_BYTES_DOWNLOADED_SO_FAR)));
                Log.d(TAG,
                        "Column last modified timestamp : "
                                + c.getLong(c
                                        .getColumnIndex(DownloadManager.COLUMN_LAST_MODIFIED_TIMESTAMP)));
                Log.d(TAG,
                        "Column local uri : "
                                + c.getString(c
                                        .getColumnIndex(DownloadManager.COLUMN_LOCAL_URI)));
                Log.d(TAG,
                        "Column statue : "
                                + c.getInt(c
                                        .getColumnIndex(DownloadManager.COLUMN_STATUS)));
                Log.d(TAG,
                        "Column reason : "
                                + c.getInt(c
                                        .getColumnIndex(DownloadManager.COLUMN_REASON)));
    
                int st = c.getInt(c.getColumnIndex(DownloadManager.COLUMN_STATUS));
                Toast.makeText(this, statusMessage(st), Toast.LENGTH_LONG).show();
                //Log.i(TAG, statusMessage(st));
                
                c.close();
            }
        }
    
        private String statusMessage(int st) {
            switch (st) {
            case DownloadManager.STATUS_FAILED:
                return "Download failed";
            case DownloadManager.STATUS_PAUSED:
                return "Download paused";
            case DownloadManager.STATUS_PENDING:
                return "Download pending";
            case DownloadManager.STATUS_RUNNING:
                return "Download in progress!";
            case DownloadManager.STATUS_SUCCESSFUL:
                return "Download finished";
            default:
                return "Unknown Information";
            }
        }
    
        // 监听下载结束，启用BroadcastReceiver
        BroadcastReceiver receiver = new BroadcastReceiver() {
            @Override
            public void onReceive(Context context, Intent intent) {
    
                DownloadManager dm = (DownloadManager) getSystemService(DOWNLOAD_SERVICE);
                String action = intent.getAction();
                if (DownloadManager.ACTION_DOWNLOAD_COMPLETE.equals(action)) {
    
                    long downloadId = intent.getLongExtra(
                            DownloadManager.EXTRA_DOWNLOAD_ID, 0);
                    // 查询
                    Query query = new Query();
                    query.setFilterById(downloadId);
                    Cursor c = dm.query(query);
                    if (c.moveToFirst()) {
                        int columnIndex = c
                                .getColumnIndex(DownloadManager.COLUMN_STATUS);
                        if (DownloadManager.STATUS_SUCCESSFUL == c
                                .getInt(columnIndex)) {
    
                            String uriString = c
                                    .getString(c
                                            .getColumnIndex(DownloadManager.COLUMN_LOCAL_URI));
    
                            //removeDownload(downloadId);
                            Toast.makeText(MainActivity.this,
                                    "get file complete: " + uriString, 0).show();
                            // Uri.parse(uriString);
                        }
                    }// endif
    
                }// endif
    
            }// onReceive
        };// end class receiver
    
        // 监听下载结束，启用BroadcastReceiver
        BroadcastReceiver receiver2 = new BroadcastReceiver() {
            @Override
            public void onReceive(Context context, Intent intent) {
                long downloadId = intent.getLongExtra(
                        DownloadManager.EXTRA_DOWNLOAD_ID, 0);
    
                String action = intent.getAction();
                if (DownloadManager.ACTION_NOTIFICATION_CLICKED.equals(action)) {
                    lookDownload();
                }
            }
        };//
    }