三种多线程编程方法
1 class Mythread extends Thread{
@Override
public void run(){}
}
new Mythread().start()
2 class Mythread implements Runnable{
@Override
public void run(){}
}
Mythread myThread=new Mythread();
new Thread(myThread).start();
3 new Thread{new Runnable{
@Override
public void run(){}
}.start();
异步消息处理机制（使用message更新ui）
public class MainActivity extends Activity implements OnClickListener{
Button button;
TextView text;
public static final int change=1;
private Handler handler=new Handler(){
public void handleMessage(Message ms){
switch(ms.what){
case change:
text.setText("nice to meet you");
break;
default:
break;
}
}
};
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
button=(Button) findViewById(R.id.change_Button);
text=(TextView)findViewById(R.id.text);
button.setOnClickListener(this);
}
public void onClick(View v){
switch (v.getId()) {
case R.id.change_Button:
new Thread(new Runnable(){
public void run(){
Message ms=new Message();
ms.what=change;
handler.sendMessage(ms);
}
}).start();
break;
default:
break;
}
}
}
使用AsynvTask更新ui
class DownloadTask extends AsyncTask<Void,Integer,Boolean>{
@Override
protected void onPreExecute(){
progressDialog.show();
}
@0verride
protected Boolean doInBackground(Void...params){
try{
while(true){
int downloadPercent=doDownload();
publishProgress(downloadPercent);
if(downloadPercent>=100){
break;
}
}
}catch(Exception e){
return false;
}
return true;
}
protected void onProgressUpdate(Integer...values){
progressDialog.setMessage("Download"+values[0]+"%");
}
@Override
protected void onPostExecute(Boolean result){
progressDialog.dismiss();
if(result){
Toast.makeText(context,"Download succeeded",Toast.LENGTH_SHORT).show();
}else{
Toast.makeText(context,"Download failed",Toast.LENGTH_SHORT).show();
}
}
}
定义一个服务
服务定义完成后要使用的话必须同android其他三大组件一样在manifest中注册才行 <service android:name=".MyService"></service>
在活动中启动或停止服务的话使用intent
Intent intent=new Intent(this,Myservice.class);
startService(intent);
Intent intent1=new Intent(this,Myservice.class);
stopService(intent1);或者是在服务的定义中调用stopSelf()来停止服务
public class MyService extends Service{
public IBinder onBind(Intent intent){
return null;
}
public void onCreate(){
super.onCreate();
}
public int onStartCommand(Intent inten,int flags,int startId){
return super.onStartCommand(intent,flags,startId);
}
public void onDestroy(){
super.onDestroy();
}
}
活动和服务进行通信：使用onBind（）
public class MyService extends Service{
private DownloadBinder mBinder=new DownloadBinder();
class DownloadBinder extends Binder{
public void startDownload(){
Log.d("MyService","startdownload");
}
public int getProgress(){
Log.d("MyService","getProgress")
return 0
}
}
public IBinder onBind(Intent intent){
return mBinder;
}
}
主活动中调用 先建立一个ServieceConnection匿名类
private ServiceConnection connection=new ServiceConnection(){
public void onServiceDisconnected(ComponentName name){}
public void onServiceConnected(ComponentName name,IBinder service){
MyService.DownloadBinder downloadBinder=(MyService.DownloadBinder)service;获得一个DownloadBinder实例
downloadBinder.startDownload();
downloadBinder.getProgress();
}
}
Intent bindintent=new Intent(this,MyService.class);
bindService(bindintent,connection,BIND_ANTO_CREATE);绑定服务并且绑定后自动创建
。。
unbinderService(connection);解绑，connection为前面定义的ServiceConnection实例
注意服务在任何活动中都是通用的 可以和任何activity 进行绑定
使用intentService（可以自己开启线程并且可以自动停止）
定义：
public class MyIntentService extends IntentService {
public MyIntentService( ) {
super("MyIntentService");
// TODO Auto-generated constructor stub
}
protected void onHandleIntent(Intent intent){
Log.d("MyIntentService","thread id id"+Thread.currentThread().getId());
}
public void onDestroy(){
super.onDestroy();
Log.d("MyIntentService","ondestroy exe");
}
}
在活动中启动或者的方法是一样的
Intent intentService=new Intent(this,MyIntentService.class);
startSercice(intentService);
同样要进行注册注册方法和普通服务一样的
服务的最佳实践 定时循环开启一项服务：
public class LongRunningService extends Service {
public IBinder onBind(Intent intent){
return null;
}
public int onStartCommand(Intent intent,int flags,int startId){
new Thread(new Runnable(){
public void run(){
Log.d(".","");
}
}).start();
AlarmManager manager=(AlarmManager)getSystemService(ALARM_SERVICE);
int anHour=60*60*1000;
long triggerAtTime=SystemClock.elapsedRealtime()+anHour;
Intent i=new Intent(this,AlarmReceiver.class);
PendingIntent pi=PendingIntent.getBroadcast(this,0,i,0);
manager.set(AlarmManager.ELAPSED_REALTIME_WAKEUP,triggerAtTime,pi);
return super.onStartCommand(intent, flags, startId);
}
}
定义一个广播接收器
public class AlarmReceiver extends BroadcastReceiver{
public void onReceive(Context context,Intent intent){
Intent i=new Intent(context,LongRunningService.class);
context.startService(i);
}
}
在活动中进行启动这个服务 一旦启动就会不断重复
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Intent intent=new Intent(this,LongRunningService.class);
startService(intent);
}
注意 ：现在的手机当中为了省电，当存在多个Alarm定时任务的时候，他会
把时间相近的几个任务集合在一起去唤醒cpu，所以会有一些时间上的误差，为了准确无误，可以
把服务中manager.set()改为manager.setExact()