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android进行异步更新UI的四种方式

大家都知道由于性能要求，android要求只能在UI线程中更新UI，要想在其他线程中更新UI，我大致总结了4种方式，欢迎补充纠正：

使用Handler消息传递机制；
使用AsyncTask异步任务；
使用runOnUiThread(action)方法；
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

package com.example.runonuithreadtest; import android.app.Activity; import android.os.Bundle; import android.os.Handler; import android.widget.TextView; 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。

package com.example.runonuithreadtest; import android.app.Activity; import android.os.AsyncTask; import android.os.Bundle; import android.widget.TextView; 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

package com.example.runonuithreadtest; import android.app.Activity; import android.os.Bundle; import android.widget.TextView; 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

package com.example.runonuithreadtest; import android.app.Activity; import android.os.Bundle; import android.os.Handler; import android.widget.TextView; 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");    }   });  } }

正文到此结束