Android进行异步更新UI的四种方式

jopen 5年前

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:

  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

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");     }    });   }  }
原文 http://segmentfault.com/a/1190000003702775