android开发(23)使用DownloadManager下载文件

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。

让我们看看如何使用

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";
}
}

　　

-----------------------------

最后附上完整代码，好像博客园无法上传代码了。

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();
}
}
};//
}

　　

谷歌文档：http://developer.android.com/intl/zh-CN/reference/android/app/DownloadManager.html

参考：http://blog.csdn.net/gf771115/article/details/7019033

http://stackoverflow.com/questions/3028306/download-a-file-with-android-and-showing-the-progress-in-a-progressdialog