一手遮天 Android - 后台服务: DownloadManager
示例如下:
/service/DownloadManagerDemo1.java
/**
* DownloadManager 的示例（下载任务会在通知栏显示，即使 app 被杀也能继续下载）
* 本例以一个 apk 文件下载为例，演示如何新增任务，删除任务，获取任务状态和下载进度，以及下载完成后弹出安装界面
*
* 注：
* 1、我这里模拟器运行失败，真机运行正常
* 2、请先进入 /storage/StorageDemo3.java 动态申请权限（我懒得在这里写了）
*/
package com.webabcd.androiddemo.service;
import androidx.appcompat.app.AppCompatActivity;
import android.app.DownloadManager;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.database.Cursor;
import android.net.Uri;
import android.os.Build;
import android.os.Bundle;
import android.os.Environment;
import android.os.StrictMode;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import com.webabcd.androiddemo.R;
import java.io.File;
import java.util.Locale;
public class DownloadManagerDemo1 extends AppCompatActivity {
private final String LOG_TAG = "DownloadManagerDemo1";
private Thread mThread;
private DownloadManager mDownloadManager;
private long mDownloadId = -1; // 下载任务的唯一标识
private boolean mRegistered = false;
private DownloadReceiver mDownloadReceiver;
private Button mButton1;
private Button mButton2;
private Button mButton3;
private TextView mTextView1;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_service_downloadmanagerdemo1);
mButton1 = findViewById(R.id.button1);
mButton2 = findViewById(R.id.button2);
mButton3 = findViewById(R.id.button3);
mTextView1 = findViewById(R.id.textView1);
sample();
registerReceiver();
}
private void sample() {
// 新增下载任务
mButton1.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
// 用于在 7.0 或以上系统，让下载的 apk 文件可以被直接安装（否则会因为读取不到 apk 而无法安装）
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
StrictMode.VmPolicy.Builder localBuilder = new StrictMode.VmPolicy.Builder();
StrictMode.setVmPolicy(localBuilder.build());
}
// 通过下载地址实例化 DownloadManager.Request 对象
String downloadUrl = "https://mmgrapp-75037.gzc.vod.tencent-cloud.com/secure/GodDresser/1/2/3/102027/tencentmobilemanager_20210401113919_8.11.0_android_build6724_102027.apk";
DownloadManager.Request request = new DownloadManager.Request(Uri.parse(downloadUrl));
// 移动网络和 wifi 网络均可下载
request.setAllowedNetworkTypes(DownloadManager.Request.NETWORK_MOBILE | DownloadManager.Request.NETWORK_WIFI);
// 通知栏标题
request.setTitle("download_title");
// 通知栏内容
request.setDescription("download_description");
// 7.0 或以上系统适配
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
request.setRequiresDeviceIdle(false); // 是否只能在系统空闲时执行
request.setRequiresCharging(false); // 是否只能在充电状态下执行
}
// 下载过程和下载完成后通知栏有通知消息
request.setNotificationVisibility(DownloadManager.Request.VISIBILITY_VISIBLE | DownloadManager.Request.VISIBILITY_VISIBLE_NOTIFY_COMPLETED);
// 隐藏通知栏的下载任务的消息，需要在 AndroidManifest.xml 配置权限 <uses-permission android:name="android.permission.DOWNLOAD_WITHOUT_NOTIFICATION" />
// request.setNotificationVisibility(DownloadManager.Request.VISIBILITY_HIDDEN);
// 下载文件的类型为 apk
request.setMimeType("application/vnd.android.package-archive");
// 指定文件保存地址，需要动态申请权限，否则会报错 No permission to write to...（懒得写了，请先进入 /storage/StorageDemo3.java 动态申请权限）
File file = new File(Environment.getExternalStorageDirectory(), "myTest.apk");
Log.d(LOG_TAG, "localUrl: " + Uri.fromFile(file).toString());
request.setDestinationUri(Uri.fromFile(file));
// 实例化 DownloadManager
mDownloadManager = (DownloadManager)DownloadManagerDemo1.this.getSystemService(Context.DOWNLOAD_SERVICE);
// 将下载请求加入下载队列，返回数据为该下载任务的标识
mDownloadId = mDownloadManager.enqueue(request);
Log.d(LOG_TAG, "downloadId: " + mDownloadId);
}
});
// 删除当前的下载任务（如何手动 pause/resume 呢？我不知道）
mButton2.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
if (mDownloadId > -1) {
mDownloadManager = (DownloadManager) DownloadManagerDemo1.this.getSystemService(Context.DOWNLOAD_SERVICE);
mDownloadManager.remove(mDownloadId);
}
}
});
// 跳转到系统下载界面
mButton3.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
DownloadManagerDemo1.this.startActivity(new android.content.Intent(DownloadManager.ACTION_VIEW_DOWNLOADS));
}
});
// 获取任务状态
mThread = new Thread(new Runnable() {
@Override
public void run() {
try {
while (true) {
if (mDownloadId == -1) {
continue;
}
// 实例化 DownloadManager.Query 对象
DownloadManager.Query query = new DownloadManager.Query();
// 查询指定的 downloadId（可以不指定查询条件，那样就是查询全部下载任务）
query.setFilterById(mDownloadId);
// 根据查询条件获取游标
Cursor cursor = mDownloadManager.query(query);
if (cursor.moveToFirst()) {
int downloadIdIndex = cursor.getColumnIndex(DownloadManager.COLUMN_ID);
int remoteUrlIndex = cursor.getColumnIndex(DownloadManager.COLUMN_URI);
int localUrlIndex = 0;
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N){
// 7.0 或以上系统使用 COLUMN_LOCAL_URI 字段
localUrlIndex = cursor.getColumnIndex(DownloadManager.COLUMN_LOCAL_URI);
} else {
localUrlIndex = cursor.getColumnIndex(DownloadManager.COLUMN_LOCAL_FILENAME);
}
int totalBytesIndex = cursor.getColumnIndex(DownloadManager.COLUMN_TOTAL_SIZE_BYTES);
int downloadedBytesIndex = cursor.getColumnIndex(DownloadManager.COLUMN_BYTES_DOWNLOADED_SO_FAR);
int taskStatusIndex = cursor.getColumnIndex(DownloadManager.COLUMN_STATUS);
// 以下几个字段看名字就知道意思，就不细说了
long downloadId = cursor.getLong(downloadIdIndex);
String remoteUrl = cursor.getString(remoteUrlIndex);
String localUrl = cursor.getString(localUrlIndex);
long totalBytes = cursor.getLong(totalBytesIndex);
long downloadedBytes = cursor.getLong(downloadedBytesIndex);
// 任务状态包括如下几个可能的值
// DownloadManager.STATUS_PENDING, DownloadManager.STATUS_RUNNING, DownloadManager.STATUS_PAUSED, DownloadManager.STATUS_SUCCESSFUL, DownloadManager.STATUS_FAILED
int taskStatus = cursor.getInt(taskStatusIndex);
writeMessage(String.format(Locale.US, "downloadId:%d
remoteUrl:%s
localUrl:%s
totalBytes:%d
downloadedBytes:%d
taskStatus:%d",
downloadId, remoteUrl, localUrl, totalBytes, downloadedBytes, taskStatus));
}
cursor.close();
if (Thread.interrupted()) {
break;
}
Thread.sleep(1000);
}
} catch (InterruptedException e) {
Log.d(LOG_TAG, "线程被 interrupted 了");
}
}
});
mThread.setName("thread_DownloadManagerDemo1");
mThread.setDaemon(true);
mThread.start();
}
private void writeMessage(final String message) {
runOnUiThread(new Runnable() {
@Override
public void run() {
mTextView1.setText(message);
}
});
}
@Override
public void onDestroy() {
if (mThread != null) {
mThread.interrupt();
mThread = null;
}
unregisterReceiver();
super.onDestroy();
}
// 通过监听广播，获取任务完成事件（也可以通过轮询任务的方式获取下载任务是否完成）和通知栏中的任务点击事件（这个只能通过广播来获取了）
public void registerReceiver() {
mDownloadReceiver = new DownloadReceiver();
IntentFilter filter = new IntentFilter();
filter.addAction(DownloadManager.ACTION_DOWNLOAD_COMPLETE); // 下载任务完成的广播
filter.addAction(DownloadManager.ACTION_NOTIFICATION_CLICKED); // 在通知栏点击下载任务之后的广播
this.registerReceiver(mDownloadReceiver, filter);
mRegistered = true;
}
public void unregisterReceiver() {
if (mRegistered) {
try {
this.unregisterReceiver(mDownloadReceiver);
mRegistered = false;
} catch (Exception e) {
e.printStackTrace();
}
}
}
public class DownloadReceiver extends BroadcastReceiver {
@Override
public void onReceive(Context context, Intent intent) {
// 下载任务完成
if (intent.getAction().equals(DownloadManager.ACTION_DOWNLOAD_COMPLETE)) {
// 获取当前完成的下载任务的 downloadId
long downloadId = intent.getLongExtra(DownloadManager.EXTRA_DOWNLOAD_ID, -1);
// 通过 downloadId 获取本地文件地址
DownloadManager downloadManager = (DownloadManager)context.getSystemService(Context.DOWNLOAD_SERVICE);
Uri localUri = downloadManager.getUriForDownloadedFile(downloadId);
if (localUri != null) {
// 弹出 apk 安装界面
Intent install = new Intent(Intent.ACTION_VIEW);
install.setDataAndType(localUri, "application/vnd.android.package-archive");
install.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
context.startActivity(install);
} else {
Log.e(LOG_TAG, "download error");
}
}
// 在通知栏点击下载任务之后，则跳转到系统下载界面
else if (intent.getAction().equals(DownloadManager.ACTION_NOTIFICATION_CLICKED)) {
Intent viewDownloadIntent = new Intent(DownloadManager.ACTION_VIEW_DOWNLOADS);
viewDownloadIntent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
context.startActivity(viewDownloadIntent);
}
}
}
}
/layout/activity_service_downloadmanagerdemo1.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<Button
android:id="@+id/button1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="新增下载任务" />
<Button
android:id="@+id/button2"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="删除当前的下载任务" />
<Button
android:id="@+id/button3"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="跳转到系统下载界面" />
<TextView
android:id="@+id/textView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
</LinearLayout>