Android异步更新UI的四种方式

2019-12-12 06:23:44

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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，大致有4种方式，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（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");  } }); }}

以上就是四种Android异步更新UI的方式，希望对大家的学习有所帮助。

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