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Android实现倒计时方法汇总

2019-12-12 04:09:40
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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();    }  }}

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