Android开发中经常会有倒计时的功能，下面将总结出常见的集中实现方式。
1.直接使用Handler的消息机制来实现
xml布局中文件如下：
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="horizontal" >
<Button
android:id="@+id/button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:onClick="clickButton"
android:text="开始计时" />
</LinearLayout>
java代码如下：
import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.view.View;
import android.widget.Button;
public class FirstActivity extends Activity{
private Button button;
private int count = 60;
private int COUNT_TIME = 0;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.first_activity);
button = (Button) findViewById(R.id.button);
}
private Handler handler = new Handler(){
@Override
public void handleMessage(Message msg) {
if(count <= 0){
count = 60;
button.setText("重新计时");
button.setClickable(true);
return;
}
count--;
button.setText(""+count);
sendEmptyMessageDelayed(COUNT_TIME,1000);
}
};
public void clickButton(View view){
handler.sendEmptyMessage(COUNT_TIME);
button.setClickable(false);
}
}
2.使用Timer和TimerTask，结合handler一起实现倒计时
import java.util.Timer;
import java.util.TimerTask;
import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.view.View;
import android.widget.Button;
public class FirstActivity extends Activity{
private Button button;
private int count = 30;
private int COUNT_TIME = 0;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.first_activity);
button = (Button) findViewById(R.id.button);
}
private Handler handler = new Handler(){
@Override
public void handleMessage(Message msg) {
button.setText(""+count);
if(count <= 0){
count = 30;
button.setClickable(true);
button.setText("重新计时");
timerTask.cancel(); //取消该任务
}
}
};
private Timer timer = new Timer();
private TimerTask timerTask;
public void clickButton(View view){
button.setClickable(false);
timerTask = new TimerTask() {
@Override
public void run() {
count--;
handler.sendEmptyMessage(COUNT_TIME);
}
};
timer.schedule(timerTask,0,1000); //0秒后，每过一秒钟执行一次该任务
}
@Override
protected void onDestroy() {
super.onDestroy();
//释放资源
if(timerTask != null){
timerTask.cancel();
timerTask = null;
}
if(timer != null){
timer.cancel();
timer = null;
}
}
}
3.使用android自带的原生倒计时类 CountDownTimer
import android.app.Activity;
import android.os.Bundle;
import android.os.CountDownTimer;
import android.view.View;
import android.widget.Button;
public class FirstActivity extends Activity{
private Button button;
private CountDownTimer timer;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.first_activity);
button = (Button) findViewById(R.id.button);
}
public void clickButton(View view){
button.setClickable(false);
//第一个参数：倒计时的毫秒数；第二个参数：接收onTick回调的时间间隔
timer = new CountDownTimer(30000, 10) {
public void onTick(long millisUntilFinished) {
button.setText(millisUntilFinished / 1000 + "秒");
}
public void onFinish() {
button.setText("重新计时");
button.setClickable(true);
}
};
timer.start();
}
@Override
protected void onDestroy() {
super.onDestroy();
if(timer != null){
timer.cancel();
}
}
}
以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持脚本之家。
