四种异步更新Android的方式

1，使用Handler消息传递机制；

2，使用AsyncTask异步任务；

3，使用runOnUiThread(action)方法；

4，使用Handler的post(Runnabel r)方法；

下面分别使用四种方式来更新一个TextView。

1.使用Handler消息传递机制

public class MainActivity extends Activity {
private TextView tv;
Handler handler = new Handler()
{
public void handleMessage(android.os.Message msg) {
if(msg.what==0x123)
{
tv.setText("更新后的TextView");
}
};
};
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
tv = (TextView) findViewById(R.id.tv);
new MyThread().start();
}
class MyThread extends Thread
{
@Override
public void run() {
//延迟两秒更新
try {
Thread.sleep(2000);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
handler.sendEmptyMessage(0x123);
}
}
}

2. 使用AsyncTask异步任务

//注：更新UI的操作只能在onPostExecute(String result)方法中。
public class MainActivity extends Activity {
private TextView tv;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
tv = (TextView) findViewById(R.id.tv);
new Yibu().execute();
}
class Yibu extends AsyncTask<String, String, String>
{
@Override
protected String doInBackground(String... params) {
try {
Thread.sleep(2000);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return null;
}
@Override
protected void onPostExecute(String result) {
// TODO Auto-generated method stub
tv.setText("更新后的TextView");
}
}
}

3. 使用runOnUiThread(action)方法

public class MainActivity extends Activity {
private TextView tv;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
tv = (TextView) findViewById(R.id.tv);
new MyThread().start();
}
class MyThread extends Thread
{
@Override
public void run() {
runOnUiThread(new Runnable() {
@Override
public void run() {
// TODO Auto-generated method stub
try {
//延迟两秒更新
Thread.sleep(2000);
} catch (InterruptedException e) {
e.printStackTrace();
}
tv.setText("更新后的TextView");
}
});
}
}
}

4. 使用Handler的post(Runnabel r)方法

public class MainActivity extends Activity {
private TextView tv;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
tv = (TextView) findViewById(R.id.tv);
Handler handler = new Handler();
handler.post(new Runnable(){
@Override
public void run() {
try {
//延迟两秒更新
Thread.sleep(2000);
} catch (InterruptedException e) {
e.printStackTrace();
}
tv.setText("更新后的TextView");
}
});
}
}