手动Handler与Thread处理UI数据同步问题

(1)在Android 2.3以前，为防止ANR（Application Not Responding），Google是不赞成将网络连接等一系列耗时操作直接放到应用主线程进行的，推荐将这类操作放在子线程内；而Android 4.0版本开始，Google强制要求这类操作必须在子线程内进行，否则将抛出 NetworkOnMainThreadException 异常。

(2)操作UI必须只能在主线程内进行，否则报“Can’t create handler inside thread that has not called Looper.prepare()”错误。注意Toast 也属于UI操作

Thread与Handler的简单使用：

public class TestActivity extends Activity {
//自定义数据处理handler
private Handler myHandler = new Handler() {
@Override
public void handleMessage(Message msg) {
//更新UI数据
if (msg.what == 1) {
String message = (String) msg.obj;
Toast.makeText(TestActivity.this, message, Toast.LENGTH_SHORT).show();
}
}
};

@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
this.setContentView(R.layout.test);

Button btnLoad = (Button) this.findViewById(R.id.btnLoad);
btnLoad.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Thread thread = new Thread() {
@Override
public void run() {
try {
Thread.sleep(1000*10);

Message message = new Message();
message.what = 1;
message.obj = "测试调用完成";

//向主线程发送数据
myHandler.sendMessage(message);
} catch (Exception e) {
e.printStackTrace();
Log.e(TestActivity.class.toString(), e.getMessage());
}
}
};
thread.start();
}
});
}
}