版权声明: https://blog.csdn.net/JerehEdu/article/details/50735240
Servic与Activity相比它没有界面,主要是在后台执行一些任务,Service有两种启动方法startService()和bindService(),startService方式Service不可交互,可一直在后台即便应用结束,bindService方式可通过ServiceConnection获得运行的Service实例的方式实现Activity和Service之间的交互,通常Activity退出则绑定的服务也就取消了。我们可以通过同时执行启动服务和绑定服务的方式实现Service交互同时又使服务可一直在后台运行直到任务完成,下面我们就使用Service来实现Apk下载任务
实现如图所示效果:
一、编写应用起始界面(CheckUpdateActivity) |
单击“检查版本”执行代码如下:
public void checkUpdate(View view){
//先进行网络版本检查,代码这里不做讲解
showDownload();//转到下载界面
}
public void showDownload(){
Intent intent=new Intent(CheckUpdateActivity.this,DownloadActivity.class);
startActivity(intent);
}
二、 Activity与Service通信实现App下载(DownloadActivity+DownloadService) |
1、DownloadActivity
1.1先看一下界面
xml文件如下:
<RelativeLayout ...>
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textAppearance="?android:attr/textAppearanceLarge"
android:text="正在下载"
android:id="@+id/textView"
android:layout_alignParentTop="true" />
<ProgressBar
style="?android:attr/progressBarStyleHorizontal"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="@+id/pbDownload"
android:layout_below="@+id/textView"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"
android:max="100"
android:progress="0"
android:indeterminate="false" />
<Button
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="停止"
android:id="@+id/btStop"
android:layout_below="@+id/pbDownload"
android:layout_alignLeft="@+id/pbDownload"
android:layout_alignStart="@+id/pbDownload" android:onClick="onCancel" />
</RelativeLayout>
1.2、DownloadActivity代码:
1.2.1构建界面:
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_download);
pbDownload=(ProgressBar)super.findViewById(R.id.pbDownload);
app=(MyApp)super.getApplication();
}
1.2.2 在onResume()中启动下载服务:
@Override
protected void onResume() {
super.onResume();
startDownload();
}
private void startDownload(){
if(!app.isDownloadIng()){
Intent intent=new Intent(DownloadActivity.this,DownloadService.class);
super.startService(intent);//启动服务下载服务,可以确保应用结束下载服务仍然执行
super.bindService(intent, conn, Service.BIND_AUTO_CREATE);//同时绑定服务,可通过ServiceConnection获得Binder实现与Service的通信
app.setIsDownloadIng(true);
}
}
1.2.3创建ServiceConnnection
private DownloadService.DownloadBind bind;
private ServiceConnection conn=new ServiceConnection() {
@Override
public void onServiceConnected(ComponentName name, IBinder service) {
bind=(DownloadService.DownloadBind)service;//获得binder
bind.start();//调用DownloadService实例中的start(),执行后台下载任务
bind.setOnBackResult(result);//调用DownloadService实例中的setOnBackResult()
}
@Override
public void onServiceDisconnected(ComponentName name) {
bind=null;
}
};
1.2.4定义回调接口(ICallbackResult),实现根据下载的百分比设置进度条
public interface ICallbackResult {
public void OnBackResult(Object Result);
}
private ICallbackResult result=new ICallbackResult() {
@Override
public void OnBackResult(Object result) {
if("finish".equals(result)){//如果传入“finish”表示下载完成
finish();
isFinished=true;
return ;
}
int progress=(Integer)result;
pbDownload.setProgress(progress);//改变进度条
}
};
1.2.5取消下载,单击停止按钮
public void onCancel(View view){
isCancel=true;
app.setIsDownloadIng(false);
bind.cancelNotification();
finish();
}
1.2.5 Activity结束,停止服务
protected void onDestroy() {
super.onDestroy();
if(isFinished||isCancel){//如果下载完成或用户取消下载停止后台服务,否则服务仍在后台运行
stopService(new Intent(this, DownloadService.class));//停止后台服务
}
if(bind!=null){
unbindService(conn);//取消服务绑定
}
}
2、使用DownloadService承载下载任务
2.1初始化
private MyApp app;
private NotificationManager notificationManager;
@Override
public void onCreate() {
super.onCreate();
app=(MyApp)super.getApplication();
notificationManager=(NotificationManager)super.getSystemService(Context.NOTIFICATION_SERVICE);
}
2.2启动服务
@Override
public int onStartCommand(Intent intent, int flags, int startId) {
isStart=true;
return Service.START_STICKY;
}
2.3绑定服务
@Override
public IBinder onBind(Intent intent) {
isStart=true;
return new DownloadBind();
}
2.4 DownloadBind—— Service实例中Binder组件,实现与DownloadActivity之间通信
public class DownloadBind extends Binder{
public void start(){
startupNotification();//在信息栏显示下载通知信息
startDownload();//执行下载任务
}
public void setOnBackResult(DownloadActivity.ICallbackResult iCallbackResult){
callbackResult=iCallbackResult;
}
public void cancelNotification(){
mNotification.tickerText="已经取消下载";
notificationManager.cancel(NOTIFY_ID);//取消通知栏信息
stopDownload=true;
}
}
2.5 实现向提示栏发送下载通知
执行效果:
startupNotifiaction()代码:
private final int NOTIFY_ID=0;
private Notification mNotification;
private void startupNotification(){
mNotification=new NotificationCompat.Builder(this).build();
mNotification.icon=R.mipmap.ic_launcher;
mNotification.tickerText="正在下载";
mNotification.defaults=Notification.DEFAULT_SOUND;
RemoteViews view=new RemoteViews(super.getPackageName(),R.layout.notification_download);
mNotification.contentView=view;
Intent intent=new Intent(this,DownloadActivity.class);
intent.setFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP);
PendingIntent contentIntent=PendingIntent
.getActivity(this, 0, intent, PendingIntent.FLAG_UPDATE_CURRENT);
intent.setAction(Intent.ACTION_MAIN);
intent.addCategory(Intent.CATEGORY_LAUNCHER);
mNotification.contentIntent=contentIntent;
notificationManager.notify(NOTIFY_ID, mNotification);
}
2.6 startDownload()启动线程执行下载任务:
private Thread downloadThread;
private void startDownload(){
downloadThread=new Thread(new Runnable() {
@Override
public void run() {
downApk();//这里模拟实现网络下载功能
}
});
downloadThread.start();
}
downApk()实现连接网络并下载并保存文件,这里模拟实现网络下载功能
private int progress=0;
private int lastLength=10*1024*1024;//剩余文件的大小,初始值为文件总尺寸
private int count=0;//已经下载的数据大小
private boolean stopDownload=false;
private void downApk(){
while(lastLength>0&&!stopDownload){
try {
Thread.sleep(2000);
count+=1*1024*1024;
lastLength=lastLength-1*1024*1024;
progress=(int)((float)count/(10*1024*1024)*100);
if(progress>1){
Message msg=mhandler.obtainMessage();
msg.what=1;
msg.arg1=progress;
mhandler.sendMessage(msg);
callbackResult.OnBackResult(progress);//通过ICallBackResult回调OnBackResult(),实现更改DownloadActivity中进度条的值
}
} catch (InterruptedException e) {
e.printStackTrace();
}
}
mhandler.sendEmptyMessage(0);//表示下载完成
app.setIsDownloadIng(false);
callbackResult.OnBackResult("finish");
}
2.7 文件下载的异步通信
private Handler mhandler=new Handler(){
@Override
public void handleMessage(Message msg) {
switch (msg.what){
case 0://表示下载完成
stopSelf();//停止当前服务
notificationManager.cancel(NOTIFY_ID);//关闭下载提示栏
isStart=false;
break;
case 1://表示产生>1的百分比的变化
int progress=(Integer)msg.arg1;
RemoteViews contentView=mNotification.contentView;
contentView.setTextViewText(R.id.tvProgress,progress+"%");//显示百分比数据
contentView.setProgressBar(R.id.pbUpdate, 100, progress, false);//改变进度条
mNotification.defaults=0;//取消声音提示
notificationManager.notify(NOTIFY_ID, mNotification);//通知下载提示栏的更新
break;
}
}
};
三、其他 |
3.1 MyApp记录应用共享的信息数据
public class MyApp extends Application {
private boolean isDownloadIng=false;//记录是否正在下载应用
@Override
public void onCreate() {
super.onCreate();
}
public boolean isDownloadIng() {
return isDownloadIng;
}
public void setIsDownloadIng(boolean isDownloadIng) {
this.isDownloadIng = isDownloadIng;
}
}
3.2 AndroidMainifest.xml
<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme"
android:name="com.jerehedu.service.MyApp">
<activity
android:name="com.jerehedu.service.CheckUpdateActivity"
android:label="@string/title_activity_check_update" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity
android:name="com.jerehedu.service.DownloadActivity"
android:label="@string/title_activity_download" >
</activity>
<service
android:name="com.jerehedu.service.DownloadService"
android:enabled="true"
android:exported="true" >
</service>
</application>
作者:
杰瑞教育
出处: http://www.cnblogs.com/jerehedu/
版权声明:本文版权归烟台杰瑞教育科技有限公司和CSDN共有,欢迎转载,但未经作者同意必须保留此段声明,且在文章页面明显位置给出原文连接,否则保留追究法律责任的权利。
技术咨询:
出处: http://www.cnblogs.com/jerehedu/
版权声明:本文版权归烟台杰瑞教育科技有限公司和CSDN共有,欢迎转载,但未经作者同意必须保留此段声明,且在文章页面明显位置给出原文连接,否则保留追究法律责任的权利。
技术咨询:
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