Android 在服务中使用活套与使用单独的线程相同吗?
在文档()中的这个示例中,我们使用线程的“looper”,并在服务类中使用它,然后服务将像在单独的线程中一样工作Android 在服务中使用活套与使用单独的线程相同吗?,android,multithreading,service,looper,Android,Multithreading,Service,Looper,在文档()中的这个示例中,我们使用线程的“looper”,并在服务类中使用它,然后服务将像在单独的线程中一样工作 public class HelloService extends Service { private Looper mServiceLooper; private ServiceHandler mServiceHandler; // Handler that receives messages from the thread private final class
public class HelloService extends Service {
private Looper mServiceLooper;
private ServiceHandler mServiceHandler;
// Handler that receives messages from the thread
private final class ServiceHandler extends Handler {
public ServiceHandler(Looper looper) {
super(looper);
}
@Override
public void handleMessage(Message msg) {
// Normally we would do some work here, like download a file.
// For our sample, we just sleep for 5 seconds.
long endTime = System.currentTimeMillis() + 5*1000;
while (System.currentTimeMillis() < endTime) {
synchronized (this) {
try {
wait(endTime - System.currentTimeMillis());
} catch (Exception e) {
}
}
}
// Stop the service using the startId, so that we don't stop
// the service in the middle of handling another job
stopSelf(msg.arg1);
}
}
@Override
public void onCreate() {
// Start up the thread running the service. Note that we create a
// separate thread because the service normally runs in the process's
// main thread, which we don't want to block. We also make it
// background priority so CPU-intensive work will not disrupt our UI.
HandlerThread thread = new HandlerThread("ServiceStartArguments",
Process.THREAD_PRIORITY_BACKGROUND);
thread.start();
// Get the HandlerThread's Looper and use it for our Handler
mServiceLooper = thread.getLooper();
mServiceHandler = new ServiceHandler(mServiceLooper);
}
@Override
public int onStartCommand(Intent intent, int flags, int startId) {
Toast.makeText(this, "service starting", Toast.LENGTH_SHORT).show();
// For each start request, send a message to start a job and deliver the
// start ID so we know which request we're stopping when we finish the job
Message msg = mServiceHandler.obtainMessage();
msg.arg1 = startId;
mServiceHandler.sendMessage(msg);
// If we get killed, after returning from here, restart
return START_STICKY;
}
@Override
public IBinder onBind(Intent intent) {
// We don't provide binding, so return null
return null;
}
@Override
public void onDestroy() {
Toast.makeText(this, "service done", Toast.LENGTH_SHORT).show();
}
}
公共类HelloService扩展服务{
专用活套;
私有服务处理程序mServiceHandler;
//从线程接收消息的处理程序
私有最终类ServiceHandler扩展处理程序{
公共服务处理程序(活套-活套){
超级(活套);
}
@凌驾
公共无效handleMessage(消息消息消息){
//通常我们会在这里做一些工作,比如下载一个文件。
//对于我们的示例,我们只需睡眠5秒钟。
long-endTime=System.currentTimeMillis()+5*1000;
while(System.currentTimeMillis()
谢谢调用thread.start()时,线程(一个HandlerThread
)在onCreate
中启动
,然后您将获得对该线程的活套
的引用(每个HandlerThread
仅创建一个活套
),以创建处理程序
,并且处理程序
用于向线程发布消息。循环器是在while(true)
循环中等待消息的对象
每次向服务
发送命令时,服务
都会通过处理程序
向句柄线程
发送消息
仔细看一下源代码将帮助您更好地理解它是如何工作的。有一篇关于Handler
s和Looper
s的精彩文章
您还可以使用实例来避免实例化自己的线程