March
29th,
2017
original post at hetaodie.github.io
目录
AsyncTask的基本结构:
例子
定义一个延时操作,用于模拟下载
public class DelayOperator {
//延时操作,用来模拟下载
public void delay()
{
try {
Thread.sleep(1000);
}catch (InterruptedException e){
e.printStackTrace();;
}
}
}
自定义AsyncTask:
public class MyAsyncTask extends AsyncTask<Integer,Integer,String>
{
private TextView txt;
private ProgressBar pgbar;
public MyAsyncTask(TextView txt,ProgressBar pgbar)
{
super();
this.txt = txt;
this.pgbar = pgbar;
}
//该方法不运行在UI线程中,主要用于异步操作,通过调用publishProgress()方法
//触发onProgressUpdate对UI进行操作
@Override
protected String doInBackground(Integer... params) {
DelayOperator dop = new DelayOperator();
int i = 0;
for (i = 10;i <= 100;i+=10)
{
dop.delay();
publishProgress(i);
}
return i + params[0].intValue() + "";
}
//该方法运行在UI线程中,可对UI控件进行设置
@Override
protected void onPreExecute() {
txt.setText("开始执行异步线程~");
}
//在doBackground方法中,每次调用publishProgress方法都会触发该方法
//运行在UI线程中,可对UI控件进行操作
@Override
protected void onProgressUpdate(Integer... values) {
int value = values[0];
pgbar.setProgress(value);
}
}
MainActivity.java:
public class MyActivity extends ActionBarActivity {
private TextView txttitle;
private ProgressBar pgbar;
private Button btnupdate;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
txttitle = (TextView)findViewById(R.id.txttitle);
pgbar = (ProgressBar)findViewById(R.id.pgbar);
btnupdate = (Button)findViewById(R.id.btnupdate);
btnupdate.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
MyAsyncTask myTask = new MyAsyncTask(txttitle,pgbar);
myTask.execute(1000);
}
});
}
}
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