Android多线程使用
2018-04-13 本文已影响28人
关玮琳linSir
Android多线程使用
使用目的
-
解决耗时任务
文件IO、联网请求、数据库操作、RPC -
提高并发能力
同一时间处理更多事情 -
防止ANR
InputDispatching Timeout：输入事件分发超时5s（触摸或按键）
Service Timeout：服务20s内未执行完
BroadcastQueue Timeout：前台广播10s内未执行完
ContentProvider Timeout：内容提供者执行超时 -
避免掉帧
要达到每秒60帧，每帧必须16ms处理完
使用方式
1.Thread
1.new Thread,重载run方法
2.实现Runable接口，作为参数传给Thread
public static void main(String[] args){
//Android中 UI线程的Id恒定为1
System.out.println("UI Thread Id : "+Thread.currentThread().getId());
new Thread(){
@Override
public void run() {
System.out.println("run in thread "+Thread.currentThread().getId());
}
}.start();
Runnable runnable = new Runnable() {
@Override
public void run() {
// TODO: 2016/12/2
System.out.println("run in thread "+Thread.currentThread().getId());
}
};
new Thread(runnable).start();
}
2.AsyncTask
android特有的轻量级异步任务类，它可以在线程池中执行后台任务，然后把执行进度和结果传递给主线程中更新UI。但不适合特别耗时的后台任务。
public class MyTask extends AsyncTask<String,Integer,String> {
String TAG = "haha";
@Override
protected void onPreExecute() {
Log.d(TAG,"onPreExecute run in thread "+Thread.currentThread().getId());
}
//只有这个方法在后台执行，其他方法都在UI线程
@Override
protected String doInBackground(String... params) {
Log.d(TAG,"doInBackground run in thread "+Thread.currentThread().getId());
//传入的参数和execute中传入参数相同
Log.d(TAG,"input param "+params[0]);
//此方法将回调onProgressUpdate 用于进度更新
publishProgress(5);
//此return的信息将传递到onPostExecute
return "task done!";
}
@Override
protected void onProgressUpdate(Integer... values) {
Log.d(TAG,"onProgressUpdate run in thread "+Thread.currentThread().getId());
Log.d(TAG,"update progress "+values[0]);
}
@Override
protected void onPostExecute(String s) {
Log.d(TAG,"onPostExecute run in thread "+Thread.currentThread().getId());
Log.d(TAG,"onPostExecute input "+s);
}
}
3.HandlerThread
HandlerThread实际上是一个带有Looper的Thread，从而可向子线程传递消息。
@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//HandlerThread 其实就是一个带有Looper的Thread
HandlerThread handlerThread = new HandlerThread("handler-thread");
handlerThread.start();
Log.d(TAG,"handlerthread id :"+handlerThread.getId());
//用handlerThread的looper生成handler 用于向子线程中发送消息、runnable 等
Handler handler = new Handler(handlerThread.getLooper()){
@Override
public void handleMessage(Message msg) {
Log.d(TAG,"handleMessage received in thread "+Thread.currentThread().getId());
Log.d(TAG,"received message is "+msg.obj);
}
};//必须先start thread
Runnable runnable = new Runnable() {
@Override
public void run() {
Log.d(TAG,"this runnable run in thread "+Thread.currentThread().getId());
}
};
//使runnable在子线程（即handlerThread线程执行）
handler.post(runnable);
//此消息发送至handlerThread线程
Message message = new Message();
message.obj = "test message";
handler.sendMessage(message);
}
