Android开发之初级开发_handler消息发送机制

MainActivity.java

import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.Toast;

public class MainActivity extends Activity
{
    private Button btn_start, btn_end;
    Runnable runnable;

    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        btn_start = (Button) findViewById(R.id.start);
        btn_end = (Button) findViewById(R.id.end);
        final Handler handler = new Handler();
        runnable = new Runnable()
        {

            public void run()
            {
                Toast.makeText(MainActivity.this, "这是一个handler实例", Toast.LENGTH_SHORT).show();
                handler.postDelayed(runnable, 5000);
            }
        };
        btn_start.setOnClickListener(new OnClickListener()
        {

            public void onClick(View v)
            {
                handler.post(runnable);
            }
        });
        btn_end.setOnClickListener(new OnClickListener()
        {

            public void onClick(View v)
            {
                handler.removeCallbacks(runnable);
            }
        });
    }

}

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:gravity="center"
    android:orientation="vertical" >

    <Button
        android:id="@+id/start"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="发送handler" />

    <Button
        android:id="@+id/end"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="停止handler" />

</LinearLayout>