应用更新是每个app都会有的功能模块,而文件下载在App中也经常有需要它的地方,比如我自己,公司的项目需要查看合同,所以需要先下载到本地。所以,基于这些需求,觉得需要有封装的必要性。 实际上Android中已经提供了一个DownloadManager类来实现的下载的功能,起初我也打算基于它进行封装,但是网上说某些机型的系统中已经被厂家删掉了。所谓万丈高楼平地起,从头开始:
1. DownloadManager类:基于OkHttp实现下载功能
a) 添加OkHttp的依赖:
compile 'com.squareup.okhttp3:okhttp:3.9.0'
b) 新建一个回调接口DownloadCallBack:
public interface DownloadCallBack {
/**
* 下载成功的回调
*
* @param filename
*/
void onComplete(String filename);
/**
* 下载失败的回调
*
* @param t
*/
void onError(Throwable t);
/**
* 进度更新的回调
*
* @param filename
* @param percent
*/
void onProgress(String filename, int percent);
}
c) 然后就是DownloadManager类的实现:
public class DownloadManager {
private DownloadCallBack mDownloadCallBack;
private int lastProgress;
public DownloadManager(DownloadCallBack callBack) {
this.mDownloadCallBack = callBack;
}
/**
* @param destDir 文件存放的目录
* @param url 下载url
* @param readLen 进行流操作时的字节单位数
*/
public void download(final String destDir, final String url, final int readLen) {
/*
构造文件存放目录的File对象.
*/
File file = new File(destDir);
file.mkdirs();
/*
构造请求
*/
OkHttpClient client = new OkHttpClient();
Request request = new Request.Builder()
.url(url)
.build();
/*
异步请求
*/
client.newCall(request).enqueue(new Callback() {
@Override
public void onFailure(Call call, IOException e) {
}
@Override
public void onResponse(Call call, Response response) throws IOException {
InputStream is = null;
FileOutputStream fos = null;
try {
is = response.body().byteStream();
//熟悉的流读取和写入操作
byte[] buff = new byte[readLen];
int len;
long current = 0;
long total = response.body().contentLength();
fos = new FileOutputStream(destDir + getFileName(url));
lastProgress = 0;
while ((len = is.read(buff)) != -1) {
current += len;
fos.write(buff, 0, len);
if (mDownloadCallBack != null) {
//计算下载进度并回调
int progress = (int) (current * 100 / total);
if (progress > lastProgress) {
mDownloadCallBack.onProgress(destDir + getFileName(url), progress);
lastProgress = progress;
}
}
}
fos.flush();
response.body().close();
if (mDownloadCallBack != null) {
mDownloadCallBack.onComplete(destDir + getFileName(url));
}
} catch (IOException e) {
if (mDownloadCallBack != null) {
mDownloadCallBack.onError(e);
}
} finally {
StreamUtils.close(fos);
StreamUtils.close(is);
}
}
});
}
public String getFileName(String url) {
return url.substring(url.lastIndexOf("/"));
}
}
三个方法:
- 构造器:接收一个DownloadCallBack的参数
- getFileName():根据url来截取文件名并返回
-
download():下载功能的具体实现。说明三点:
- file.mkdirs():没有进行file是否存在的判断操作,因为发现mkdirs()方法中已经做了判断。
-
- onResponse():运行在子线程中
-
StreamUtils类的实现:
public class StreamUtils { public static void close(Closeable stream) { try { if (stream != null) { stream.close(); } } catch (IOException e) { e.printStackTrace(); } } }
2.DownloadService类:下载服务类,负责下载动作的发起以及Notification的更新显示。代码如下:
public class DownloadService extends Service {
private NotificationCompat.Builder mBuilder;
private NotificationManagerCompat mNotificationManager;
private DownloadManager mDownloadManager;
class DownloadBinder extends Binder {
public void startDownload(String destDir, final String url, final int readLen) {
mDownloadManager.download(destDir, url, readLen);
}
}
@Nullable
@Override
public IBinder onBind(Intent intent) {
initNotification();
mDownloadManager = new DownloadManager(new DownloadCallBack() {
@Override
public void onComplete(String filename) {
Log.i("TAG", "DownloadService onComplete()");
// updateNotification(101);
installApk(filename);
stopSelf();
}
@Override
public void onError(Throwable t) {
}
@Override
public void onProgress(String filename, int percent) {
// if (percent > 95) {
Log.e("TAG", "percent = " + percent);
// }
updateNotification(percent);
}
});
return new DownloadBinder();
}
private void initNotification() {
mBuilder = new NotificationCompat.Builder(this, "main")
.setSmallIcon(R.mipmap.ic_launcher)
.setContentTitle("正在下载")
.setContentText("0%");
mNotificationManager = NotificationManagerCompat.from(this);
mNotificationManager.notify(100, mBuilder.build());
}
private void updateNotification(int progress) {
mBuilder.setProgress(100, progress, false);
mBuilder.setContentText(progress + "%");
mNotificationManager.notify(100, mBuilder.build());
}
//跳转到应用安装界面进行安装
private void installApk(String filename) {
File apkFile = new File(filename);
Intent intent = new Intent(Intent.ACTION_VIEW);
intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
Uri uri = FileProvider.getUriForFile(this, "com.xlh.downloadmanager.fileProvider", apkFile);
intent.addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);
intent.setDataAndType(uri, "application/vnd.android.package-archive");
} else {
intent.setDataAndType(Uri.fromFile(apkFile), "application/vnd.android.package-archive");
}
startActivity(intent);
}
}
唯一需要注意的地方就是:别忘了在AndroidManifest.xml进行Service注册以及适配7.0系统的FileProvider的使用:
a. 在res目录下新建xml目录,并在xml目录下新建file_paths.xml文件(文件名任意)
<paths xmlns:android="http://schemas.android.com/apk/res/android">
<external-path
name="external_files"
path="."/>
<external-path
name="files_root"
path="Android/data/com/pgyersdk"/>
<external-path
name="external_storage_root"
path="."/>
</paths>
b. 在AndroidManifest.xml添加如下:
<provider
android:name="android.support.v4.content.FileProvider"
android:authorities="com.xlh.downloadmanager.fileProvider"
android:exported="false"
android:grantUriPermissions="true">
<meta-data
android:name="android.support.FILE_PROVIDER_PATHS"
android:resource="@xml/file_paths" />
</provider>
3.UpdateManager类:应用更新的统一对外类。
public class UpdateManager {
private static final int READ_LENGTH = 512;
private String url;
private ServiceConnection conn = new ServiceConnection() {
@Override
public void onServiceConnected(ComponentName name, IBinder service) {
DownloadService.DownloadBinder mBinder = (DownloadService.DownloadBinder) service;
mBinder.startDownload(Environment.getExternalStorageDirectory() + "/download", url, READ_LENGTH);
}
@Override
public void onServiceDisconnected(ComponentName name) {
}
};
public void startDownload(Context context, final String url) {
this.url = url;
startAndBindService(context);
}
public void unregister(Context context) {
if (conn != null) {
context.unbindService(conn);
}
}
/*------------------------------------------------------------------------*/
private void startAndBindService(Context context) {
Intent intent = new Intent(context, DownloadService.class);
context.startService(intent);
context.bindService(intent, conn, Context.BIND_AUTO_CREATE);
}
只需要注意一点:对于DownloadService,使用了两种方式启动了它:start方式和bind方式。这样做的好处就是:既方便了和服务进行通信,同时在退出应用时下载任务不会中断。与此同时,这样会影响Service的生命周期,既需要调用了Service的stopSelf或者Context的stopService,又需要调用Context的unbindService才能使服务停止。详情可见官方文档的相关描述,这里就不贴了。
4.编写MainActivity,进行功能测试:
a) 布局文件的编写:
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
tools:context="com.dc3658.download.MainActivity">
<Button
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:onClick="download"
android:text="开始下载" />
</LinearLayout>
b. MainActivity的实现:
class MainActivity : AppCompatActivity() {
private val manager = UpdateManager()
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
}
override fun onRequestPermissionsResult(requestCode: Int, permissions: Array<String>, grantResults: IntArray) {
MPermissionUtils.onRequestPermissionsResult(requestCode, permissions, grantResults)
super.onRequestPermissionsResult(requestCode, permissions, grantResults)
}
override fun onDestroy() {
super.onDestroy()
manager.unregister(this)
}
fun download(view: View) {
MPermissionUtils.requestPermissionsResult(this, 100, arrayOf(Manifest.permission.WRITE_EXTERNAL_STORAGE), object : MPermissionUtils.OnPermissionListener {
override fun onPermissionGranted() {
manager.startDownload(this@MainActivity, "xxxxxxxxxxxxxxxx")
}
override fun onPermissionDenied() {
}
})
}
}
-
这里使用了鸿洋大神的MPermissionUtils来适配6.0动态权限:
public class MPermissionUtils { private static int mRequestCode = -1; public static void requestPermissionsResult(Activity activity, int requestCode , String[] permission, OnPermissionListener callback) { requestPermissions(activity, requestCode, permission, callback); } public static void requestPermissionsResult(android.app.Fragment fragment, int requestCode , String[] permission, OnPermissionListener callback) { requestPermissions(fragment, requestCode, permission, callback); } public static void requestPermissionsResult(android.support.v4.app.Fragment fragment, int requestCode , String[] permission, OnPermissionListener callback) { requestPermissions(fragment, requestCode, permission, callback); } /** * 请求权限处理 * * @param object activity or fragment * @param requestCode 请求码 * @param permissions 需要请求的权限 * @param callback 结果回调 */ @TargetApi(Build.VERSION_CODES.M) private static void requestPermissions(Object object, int requestCode , String[] permissions, OnPermissionListener callback) { checkCallingObjectSuitability(object); mOnPermissionListener = callback; if (checkPermissions(getContext(object), permissions)) { if (mOnPermissionListener != null) mOnPermissionListener.onPermissionGranted(); } else { List<String> deniedPermissions = getDeniedPermissions(getContext(object), permissions); if (deniedPermissions.size() > 0) { mRequestCode = requestCode; if (object instanceof Activity) { ((Activity) object).requestPermissions(deniedPermissions .toArray(new String[deniedPermissions.size()]), requestCode); } else if (object instanceof android.app.Fragment) { ((android.app.Fragment) object).requestPermissions(deniedPermissions .toArray(new String[deniedPermissions.size()]), requestCode); } else if (object instanceof android.support.v4.app.Fragment) { ((android.support.v4.app.Fragment) object).requestPermissions(deniedPermissions .toArray(new String[deniedPermissions.size()]), requestCode); } else { mRequestCode = -1; } } } } /** * 获取上下文 */ private static Context getContext(Object object) { Context context; if (object instanceof android.app.Fragment) { context = ((android.app.Fragment) object).getActivity(); } else if (object instanceof android.support.v4.app.Fragment) { context = ((android.support.v4.app.Fragment) object).getActivity(); } else { context = (Activity) object; } return context; } /** * 请求权限结果,对应onRequestPermissionsResult()方法。 */ public static void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults) { if (mRequestCode != -1 && requestCode == mRequestCode) { if (verifyPermissions(grantResults)) { if (mOnPermissionListener != null) mOnPermissionListener.onPermissionGranted(); } else { if (mOnPermissionListener != null) mOnPermissionListener.onPermissionDenied(); } } } /** * 显示提示对话框 */ public static void showTipsDialog(final Context context) { new AlertDialog.Builder(context) .setTitle("提示信息") .setMessage("当前应用缺少必要权限,该功能暂时无法使用。如若需要,请单击【确定】按钮前往设置中心进行权限授权。") .setNegativeButton("取消", null) .setPositiveButton("确定", new DialogInterface.OnClickListener() { @Override public void onClick(DialogInterface dialog, int which) { startAppSettings(context); } }).show(); } /** * 启动当前应用设置页面 */ private static void startAppSettings(Context context) { Intent intent = new Intent(Settings.ACTION_APPLICATION_DETAILS_SETTINGS); intent.setData(Uri.parse("package:" + context.getPackageName())); context.startActivity(intent); } /** * 验证权限是否都已经授权 */ private static boolean verifyPermissions(int[] grantResults) { for (int grantResult : grantResults) { if (grantResult != PackageManager.PERMISSION_GRANTED) { return false; } } return true; } /** * 获取权限列表中所有需要授权的权限 * * @param context 上下文 * @param permissions 权限列表 * @return */ private static List<String> getDeniedPermissions(Context context, String... permissions) { List<String> deniedPermissions = new ArrayList<>(); for (String permission : permissions) { if (ContextCompat.checkSelfPermission(context, permission) == PackageManager.PERMISSION_DENIED) { deniedPermissions.add(permission); } } return deniedPermissions; } /** * 检查所传递对象的正确性 * * @param object 必须为 activity or fragment */ private static void checkCallingObjectSuitability(Object object) { if (object == null) { throw new NullPointerException("Activity or Fragment should not be null"); } boolean isActivity = object instanceof Activity; boolean isSupportFragment = object instanceof android.support.v4.app.Fragment; boolean isAppFragment = object instanceof android.app.Fragment; if (!(isActivity || isSupportFragment || isAppFragment)) { throw new IllegalArgumentException( "Caller must be an Activity or a Fragment"); } } /** * 检查所有的权限是否已经被授权 * * @param permissions 权限列表 * @return */ private static boolean checkPermissions(Context context, String... permissions) { if (isOverMarshmallow()) { for (String permission : permissions) { if (ContextCompat.checkSelfPermission(context, permission) == PackageManager.PERMISSION_DENIED) { return false; } } } return true; } /** * 判断当前手机API版本是否 >= 6.0 */ private static boolean isOverMarshmallow() { return Build.VERSION.SDK_INT >= Build.VERSION_CODES.M; } public interface OnPermissionListener { void onPermissionGranted(); void onPermissionDenied(); } private static OnPermissionListener mOnPermissionListener; }
- 在onDestroy回调中进行解除Service绑定
- kotlin语言,应该都好懂,只有this@MainActivity表示外部类的对象,同MainActivity.this以及匿名内部类的实现形式:通过object关键字
系列一就到这里了,在后面的系列文章中我们继续完善。谢谢大家的阅读~
代码已上传到GitHub:DownloadManager。后期代码会更新,如果需要这版的源码,可以通过如下操作:
1. 执行git log 命令:
找到日志信息为step one的,记录下step one上面的commit id,这里就是67d98e......
2. 执行git reset --hard 67d98e,如果显示HEAD is now at ...就表示版本回退成功,就能拿到此版本的代码啦~