package com.per.countdowntimer;

import android.app.Activity;
import android.os.Bundle;
import android.os.CountDownTimer;
import android.view.View;
import android.widget.TextView;


public class MainActivity extends Activity {
 private TextView mTvShow;

 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main);
  mTvShow = (TextView) findViewById(R.id.show);
 }

 /**
  * 取消倒计时
  * @param v
  */
 public void oncancel(View v) {
  timer.cancel();
 }

 /**
  * 开始倒计时
  * @param v
  */
 public void restart(View v) {
  timer.start();
 }

 private CountDownTimer timer = new CountDownTimer(10000, 1000) {

  @Override
  public void onTick(long millisUntilFinished) {
   mTvShow.setText((millisUntilFinished / 1000) + "秒后可重发");
  }

  @Override
  public void onFinish() {
   mTvShow.setEnabled(true);
   mTvShow.setText("获取验证码");
  }
 };
}

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
 android:layout_width="match_parent"
 android:layout_height="match_parent"
 android:background="@android:color/white"
 android:orientation="vertical"
 android:padding="16dp">

 <TextView
  android:id="@+id/show"
  android:layout_width="wrap_content"
  android:layout_height="wrap_content"
  android:text="@string/hello_world" />

 <Button
  android:layout_width="wrap_content"
  android:layout_height="wrap_content"
  android:layout_marginTop="10dp"
  android:onClick="restart"
  android:text="取消" />

 <Button
  android:layout_width="wrap_content"
  android:layout_height="wrap_content"
  android:layout_marginTop="10dp"
  android:onClick="oncancel"
  android:text="结束" />

</LinearLayout>