android开发过程中，经常需要更新UI的状态和文案等。这是就需要对UI进行 更新。在android中更新UI一般有三种方法，handler机制、RunOnUiThread方法以及AsyncTask异步类方法等
本文下面就这三种方法进行了演示和代码实现.
a.Handler机制通过使用消息机制来实现
b.RunOnUiThread方法是通过运行UI线程来达到更新UI的目的
c.AsyncTask是异步类，通过异步更新来更新UI
效果图如下：
（1）Java功能实现代码如下：
package com.czm.updateui; import android.os.AsyncTask;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.R.integer;
import android.app.Activity;
import android.graphics.Color;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.ProgressBar;
import android.widget.TextView; public class UpdateUIActivity extends Activity { private Button btnHandler;
private Button btnRunOnUiThread;
private Button btnAsyncTask;
private TextView tvHandler;
private TextView tvOnUiThread;
private TextView tvProgress;
private Handler uiHandler;
private ProgressBar progressBar; @Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.update_ui);
initViews();
setListeners();
}
private void initViews(){
btnHandler = (Button) findViewById(R.id.btnHandler);
btnRunOnUiThread = (Button) findViewById(R.id.btnRunOnUiThread);
btnAsyncTask = (Button)findViewById(R.id.btnAsyncTask);
tvHandler = (TextView) findViewById(R.id.tvText1);
tvOnUiThread = (TextView)findViewById(R.id.tvText2);
tvProgress = (TextView)findViewById(R.id.tvText3);
progressBar = (ProgressBar)findViewById(R.id.progressBar);
}
private void setListeners(){
uiHandler = new Handler(){ @Override
public void handleMessage(Message msg) {
// TODO Auto-generated method stub
super.handleMessage(msg);
Bundle bundle = msg.getData();
String text = bundle.getString("handler_text");
String color = bundle.getString("handler_color"); tvHandler.setText(text);
tvHandler.setBackgroundColor(Color.BLUE); } };
//通过Handler机制来更新UI
btnHandler.setOnClickListener(new OnClickListener() { @Override
public void onClick(View v) {
// TODO Auto-generated method stub
new Thread(){ @Override
public void run() {
// TODO Auto-generated method stub
Message msg =new Message();
Bundle bundle = new Bundle();
bundle.putString("handler_text", "我是由Handler更新UI后的文案");
bundle.putString("handler_color", "#0000FF");
msg.setData(bundle);
//uiHandler.sendMessageDelayed(msg, 2000);
uiHandler.sendMessage(msg);
} }.start();
}
}); //通过RunOnUiThread来更新UI
btnRunOnUiThread.setOnClickListener(new OnClickListener() { @Override
public void onClick(View v) {
// TODO Auto-generated method stub runOnUiThread(new Runnable() { @Override
public void run() {
// TODO Auto-generated method stub
tvOnUiThread.setText("我是由runOnUiThread更新UI后的文案");
tvOnUiThread.setBackgroundColor(Color.RED); }
});
}
});
//通过AsyncTask 异步任务来更新UI
btnAsyncTask.setOnClickListener(new OnClickListener() { @Override
public void onClick(View v) {
// TODO Auto-generated method stub
new MyAsyncTask().execute(0);
}
});
} private class MyAsyncTask extends AsyncTask<Integer, Integer, Integer>{ @Override
protected void onPostExecute(Integer result) {
// TODO Auto-generated method stub
super.onPostExecute(result);
tvProgress.setText("加载完成...100%");
} @Override
protected void onProgressUpdate(Integer... values) {
// TODO Auto-generated method stub
super.onProgressUpdate(values);
progressBar.setProgress((int)(values[0]));
tvProgress.setText("加载中..."+values[0]+"%");
} @Override
protected Integer doInBackground(Integer... params) {
// TODO Auto-generated method stub
Integer timer = 0;
while(timer <=100){
try {
publishProgress(timer);
timer ++;
Thread.sleep(40);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
return null;
} } }
（2）对应的UI布局xml文件代码：
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:gravity="center_horizontal"
tools:context=".UpdateUIActivity" >
<LinearLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="horizontal" >"
<Button
android:id="@+id/btnHandler"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Handler" />
<Button
android:id="@+id/btnRunOnUiThread"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="runOnUiThread" />
<Button
android:id="@+id/btnAsyncTask"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="AsyncTask" />
</LinearLayout> <TextView
android:id="@+id/tvText1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="10dp"
android:text="Handler来更新UI"
android:padding="3dp"
android:textColor="#FFF"
android:background="#666666"
android:textSize="20dp" />
<TextView
android:id="@+id/tvText2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="10dp"
android:text="RunOnUiThread来更新UI"
android:padding="3dp"
android:textColor="#FFF"
android:background="#666666"
android:textSize="20dp" /> <ProgressBar android:id="@+id/progressBar"
style="?android:attr/progressBarStyleHorizontal"
android:layout_width="fill_parent"
android:layout_height="25dp"
android:progressDrawable="@drawable/progressbar"
android:max="100"
android:progress="0"
android:layout_marginLeft="5dp"
android:layout_marginRight="5dp"
android:layout_marginTop="10dp"
/>
<TextView
android:id="@+id/tvText3"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="准备加载...0%"
android:textSize="20dp" /> </LinearLayout>