AsyncTask

来源：互联网发布：交易圣经知乎编辑：程序博客网时间：2024/05/22 03:34

import android.app.Activity;
import android.os.AsyncTask;
import android.os.Bundle;
import android.os.SystemClock;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.ProgressBar;
import android.widget.TextView;

public class MainActivity extends Activity {

   TextView tv;
   ProgressBar pb;
   @Override
   protected void onCreate(Bundle savedInstanceState) {
       super.onCreate(savedInstanceState);
       setContentView(R.layout.activity_main);


       tv = (TextView) findViewById(R.id.tv);
       pb = (ProgressBar) findViewById(R.id.pb);
       pb.setMax(3);

       new MyAsyncTask().execute("");

       // 异步任务
       // AsyncTask 抽象类
       // <Params, Progress, Result>
       new AsyncTask<String, Integer, String>() {

           //是一个线程方法处理耗时操作
           @Override
           protected String doInBackground(String... params) {
               Log.i("==============", params[0]);
               Log.i("==============", params[1]);
               Log.i("==============", params[2]);

               String result = "";
               for (int i = 0; i < params.length; i++) {
                   SystemClock.sleep(1000);
                   publishProgress(i+1);
                   result += params[i];
               }
               return result;
           }

           //当doInBackground return以后执行
           //主线程方法可以更新UI
           @Override
           protected void onPostExecute(String result) {
               tv.setText(result);
               super.onPostExecute(result);
           }

           //在doInBackground 执行之前调用的方法   做一些数据的初始化工作
           @Override
           protected void onPreExecute() {
               // TODO Auto-generated method stub

               super.onPreExecute();
           }

           //onProgressUpdate可是根据需求来调用当调用了publishProgress(values)方法的时候该方法就会被调用
           //主线程方法可以更新UI
           @Override
           protected void onProgressUpdate(Integer... values) {
               pb.setProgress(values[0]);
               super.onProgressUpdate(values);
           }



       }.execute("a","b","c");
   }

   class MyAsyncTask extends AsyncTask<String, Integer, String>{

       @Override
       protected String doInBackground(String... params) {
           // TODO Auto-generated method stub
           return null;
       }

   }

}

阅读全文

0 0