点击两次物理键退出APP

在需要退出的页面中加入代码，两秒内点击两次物理退出键即可退出APP，首先定义记录时间。

private long mTochTime = 0;
private long mWaitTime = 2000;　

然后在onKeyDown方法中写入逻辑代码即可

   @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        if (event.getAction() == KeyEvent.ACTION_DOWN && KeyEvent.KEYCODE_BACK == keyCode) {
            long currTime = System.currentTimeMillis();
            if ((currTime - mTochTime) >= mWaitTime) {
                Toast.makeText(this, "再次点击退出系统", Toast.LENGTH_SHORT).show();
                mTochTime = currTime;
            } else {
                finish();
            }
            return true;
        }
        return super.onKeyDown(keyCode, event);
    }