实现一个简单的计时器

        项目开发过程中经常会遇到这样的需求：让用户输入手机号，点击获取验证码，然后开始倒计时。所以就写了一个简单的计时器。

1.先看效果：

        


        2.实现思路：定义一个类CountDownTimerImpl继承自CountDownTimer类， 重写父类的onTick()与onFinish()方法，分别表示开始计时与计时结束。开始计时 改变控件状
   态，计时结束恢复控件初始状态。代码如下：

public class CountDownTimerImpl extends CountDownTimer {
private TextView mTextView;
/**
* @param millisInFuture The number of millis in the future from the call
* to {@link #start()} until the countdown is done and {@link #onFinish()}
* is called.
* @param countDownInterval The interval along the way to receive
* {@link #onTick(long)} callbacks.
*/
public CountDownTimerImpl(long millisInFuture, long countDownInterval) {
super(millisInFuture, countDownInterval);
}

@Override
public void onTick(long millisUntilFinished) {
mTextView.setClickable(false);//开始计时设置按钮不可点击
mTextView.setText(millisUntilFinished/1000+"秒后可重新发送");
mTextView.setBackgroundResource(R.drawable.tv_code_press);

//设置时间为红色，
String text = mTextView.getText().toString();
SpannableString spannableString=new SpannableString(text);
ForegroundColorSpan span=new ForegroundColorSpan(Color.RED);
String substring = text.substring(0, 2);
if (isNumeric(substring)){
spannableString.setSpan(span,0,2, Spanned.SPAN_INCLUSIVE_EXCLUSIVE);
}else {
spannableString.setSpan(span,0,1, Spanned.SPAN_INCLUSIVE_EXCLUSIVE);
}
mTextView.setText(spannableString);
}

@Override
public void onFinish() {
mTextView.setText("获取验证码");
mTextView.setClickable(true);
mTextView.setBackgroundResource(R.drawable.tv_code_nomol);
}

public CountDownTimerImpl(long millisInFuture, long countDownInterval, TextView textView) {
super(millisInFuture, countDownInterval);
mTextView = textView;
}

/**
* 判断字符串是否为数字
* @param str
* @return
*/
private boolean isNumeric(String str){
for (int i = 0; i < str.length(); i++){
System.out.println(str.charAt(i));
if (!Character.isDigit(str.charAt(i))){
return false;
}
}
return true;
}
}       3.使用：
mTextView= (TextView) findViewById(R.id.tv_getSecurityCode);
mTextView.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
mCountDownTimer=new CountDownTimerImpl(60000,1000,mTextView);
mCountDownTimer.start();
}
});
4.查看demo