使用Thread+Handler实现非UI线程更新UI界面

public class ThreadHandlerActivity extends Activity {
/** Called when the activity is first created. */

private static final int MSG_SUCCESS = 0;//获取图片成功的标识
private static final int MSG_FAILURE = 1;//获取图片失败的标识

private ImageView mImageView;
private Button mButton;

private Thread mThread;

private Handler mHandler = new Handler() {
public void handleMessage (Message msg) {//此方法在ui线程运行
switch(msg.what) {
case MSG_SUCCESS:
mImageView.setImageBitmap((Bitmap) msg.obj);//imageview显示从网络获取到的logo
Toast.makeText(getApplication(), getApplication().getString(R.string.get_pic_success), Toast.LENGTH_LONG).show();
break;

case MSG_FAILURE:
Toast.makeText(getApplication(), getApplication().getString(R.string.get_pic_failure), Toast.LENGTH_LONG).show();
break;
}
}
};

@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
mImageView= (ImageView) findViewById(R.id.imageView);//显示图片的ImageView
mButton = (Button) findViewById(R.id.button);
mButton.setOnClickListener(new OnClickListener() {

@Override
public void onClick(View v) {
if(mThread == null) {
mThread = new Thread(runnable);
mThread.start();//线程启动
}
else {
Toast.makeText(getApplication(), getApplication().getString(R.string.thread_started), Toast.LENGTH_LONG).show();
}
}
});
}

Runnable runnable = new Runnable() {

@Override
public void run() {//run()在新的线程中运行
HttpClient hc = new DefaultHttpClient();
HttpGet hg = new HttpGet("http://www.oschina.net/img/logo.gif");//获取oschina的logo
final Bitmap bm;
try {
HttpResponse hr = hc.execute(hg);
bm = BitmapFactory.decodeStream(hr.getEntity().getContent());
} catch (Exception e) {
mHandler.obtainMessage(MSG_FAILURE).sendToTarget();//获取图片失败
return;
}
mHandler.obtainMessage(MSG_SUCCESS,bm).sendToTarget();//获取图片成功，向ui线程发送MSG_SUCCESS标识和bitmap对象

//          mImageView.setImageBitmap(bm); //出错！不能在非ui线程操作ui元素

//          mImageView.post(new Runnable() {//另外一种更简洁的发送消息给ui线程的方法。
//
//              @Override
//              public void run() {//run()方法会在ui线程执行
//                  mImageView.setImageBitmap(bm);
//              }
//          });
}
};

}

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:layout_width="fill_parent"
android:layout_height="fill_parent">
<Button android:id="@+id/button" android:text="@string/button_name" android:layout_width="wrap_content" android:layout_height="wrap_content"></Button>
<ImageView android:id="@+id/imageView" android:layout_height="wrap_content"
android:layout_width="wrap_content" />
</LinearLayout>

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:layout_width="fill_parent"
android:layout_height="fill_parent">
<Button android:id="@+id/button" android:text="@string/button_name" android:layout_width="wrap_content" android:layout_height="wrap_content"></Button>
<ImageView android:id="@+id/imageView" android:layout_height="wrap_content"
android:layout_width="wrap_content" />
</LinearLayout>

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.zhuozhuo"
android:versionCode="1"
android:versionName="1.0">
<uses-sdk android:minSdkVersion="9" />
<uses-permission android:name="android.permission.INTERNET"></uses-permission><!--不要忘记设置网络访问权限-->

<application android:icon="@drawable/icon" android:label="@string/app_name">
<activity android:name=".ThreadHandlerActivity"
android:label="@string/app_name">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>

</application>
</manifest>

mImageView.setImageBitmap(bm)

Message obtainMessage(

int

what,Object object)

mImageView.setImageBitmap((Bitmap) msg.obj);

mImageView.post(new Runnable() {//另外一种更简洁的发送消息给ui线程的方法。@Overridepublic void run() {//run()方法会在ui线程执行mImageView.setImageBitmap(bm);}});