//记录按键时间
  private long exitTime;
  @Override
  public boolean onKeyDown(int keyCode, KeyEvent event) {
    if(keyCode == KeyEvent.KEYCODE_BACK){
      exit();
    }
    return super.onKeyDown(keyCode, event);
  }
  public void exit(){
    if ((System.currentTimeMillis()-exitTime)>2000){
      // 点击间隔大于两秒，做出提示
      Toast.makeText(getApplicationContext(), "再按一次退出应用", Toast.LENGTH_SHORT).show();
      exitTime = System.currentTimeMillis();
    }else{
      finish();
      System.exit(0);
    }
  }

// 等待加载PhoneGap
document.addEventListener("deviceready", onDeviceReady, false); 
// PhoneGap加载完毕
function onDeviceReady() {
//按钮事件
document.addEventListener("backbutton", eventBackButton, false); //返回键
document.addEventListener("menubutton", eventMenuButton, false); //菜单键
document.addEventListener("searchbutton", eventSearchButton, false); //搜索键
}
 
//返回键
function eventBackButton(){
//confirm("再点击一次退出!");
window.plugins.ToastPlugin.show_short('再点击一次退出!');
document.removeEventListener("backbutton", eventBackButton, false); //注销返回键
  //3秒后重新注册
  var intervalID = window.setInterval(
    function() {
      window.clearInterval(intervalID);
      document.addEventListener("backbutton", eventBackButton, false); //返回键
    },
    3000
  );
}
//菜单键
function eventMenuButton(){
  window.plugins.ToastPlugin.show_short('点击了 菜单 按钮!');
}
//搜索键
function eventSearchButton(){
  window.plugins.ToastPlugin.show_short('点击了 搜索 按钮!');
}