AsyncTask探究2

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作者：孙有军

在前一篇文章中我们探究了AsyncTask的执行流程，那这一篇里面就写一个小的demo，来尝试一下AsyncTask的调用。
1：布局文件：

  
<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"
    tools:context="com.example.toolbox.suspend.SuspendActivity" >

    <TextView
        android:id="@+id/async_task"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:layout_marginTop="20dip"
        android:background="@drawable/g_green_btn_selector"
        android:gravity="center"
        android:padding="10dip"
        android:text="@string/async_task"
        android:textColor="@color/white_color"
        android:textSize="16sp" />

    <TextView
        android:id="@+id/async_task_thread"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:layout_marginTop="20dip"
        android:background="@drawable/g_green_btn_selector"
        android:gravity="center"
        android:padding="10dip"
        android:text="@string/async_task_thread"
        android:textColor="@color/white_color"
        android:textSize="16sp" />

    <TextView
        android:id="@+id/async_task_result"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:layout_marginTop="20dip"
        android:background="@drawable/g_green_btn_selector"
        android:gravity="center"
        android:padding="10dip"
        android:text="@string/async_task_result"
        android:textColor="@color/white_color"
        android:textSize="16sp" />

</LinearLayout>

public class AsyncTaskActivity extends ActionBarActivity implements OnClickListener {

	TextView result;

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.async_task_activity);
		findViews();
		setViewListener();
	}

	private void findViews() {
		result = (TextView) findViewById(R.id.async_task_result);
	}

	private void setViewListener() {
		findViewById(R.id.async_task).setOnClickListener(this);
		findViewById(R.id.async_task_thread).setOnClickListener(this);
	}

	@Override
	public void onClick(View v) {
		switch (v.getId()) {
		case R.id.async_task:
			startAsyncTask(3);
			break;
		case R.id.async_task_thread:
			startAsyncTask2();
		default:
			break;
		}

	}

	private void startAsyncTask2() {
		Thread thread = new Thread(new Runnable() {

			@Override
			public void run() {
				startAsyncTask(5);
			}
		});
		thread.start();
	}

	@TargetApi(Build.VERSION_CODES.HONEYCOMB) private void startAsyncTask(int value) {
		AsyncTask<Integer, Void, Integer> task = new AsyncTask<Integer, Void, Integer>() {

			@Override
			protected Integer doInBackground(Integer... params) {
				return params[0] * params[0];
			}
			@Override
			protected void onPostExecute(Integer result) {
				Toast.makeText(AsyncTaskActivity.this, "Current Value = " + result, Toast.LENGTH_LONG).show();
				setTextValue("Current Value =" + result);
			}
		};
		if (Build.VERSION.SDK_INT >= 11) {
			task.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR,value);
		} else {
			task.execute(value);
		}
	}

	private void setTextValue(String text) {
		result.setText(text);
	}

	@Override
	protected void onDestroy() {
		super.onDestroy();
	}
}

public static void init() {
        sHandler.getLooper();
    }

public static void main(String[] args) {
5107        SamplingProfilerIntegration.start();
5108
5109        // CloseGuard defaults to true and can be quite spammy.  We
5110        // disable it here, but selectively enable it later (via
5111        // StrictMode) on debug builds, but using DropBox, not logs.
5112        CloseGuard.setEnabled(false);
5113
5114        Environment.initForCurrentUser();
5115
5116        // Set the reporter for event logging in libcore
5117        EventLogger.setReporter(new EventLoggingReporter());
5118
5119        Security.addProvider(new AndroidKeyStoreProvider());
5120
5121        Process.setArgV0("<pre-initialized>");
5122
5123        Looper.prepareMainLooper();
5124
5125        ActivityThread thread = new ActivityThread();
5126        thread.attach(false);
5127
5128        if (sMainThreadHandler == null) {
5129            sMainThreadHandler = thread.getHandler();
5130        }
5131
5132        AsyncTask.init();
5133
5134        if (false) {
5135            Looper.myLooper().setMessageLogging(new
5136                    LogPrinter(Log.DEBUG, "ActivityThread"));
5137        }
5138
5139        Looper.loop();
5140
5141        throw new RuntimeException("Main thread loop unexpectedly exited");
5142    }
5143}