Cordova for android如何在App中处理退出按钮事件

       项目需要在HTML5 Android App中加入对返回键的处理，发现直接在Activity中加返回键处理代码不起作用，分析cordova源码发现返回键已经被WebView处理掉了，所以只能在js中处理返回键了！

 @Override
	public boolean onKeyDown(int keyCode, KeyEvent event) {
		if (keyCode == KeyEvent.KEYCODE_BACK) {
			if (exit > 1) {
				finish();
			} else {
				Toast.makeText(this, R.string.toast_exit, Toast.LENGTH_SHORT)
						.show();
				exit++;
			}
			return true;
		} else {
			return super.onKeyDown(keyCode, event);
		}
	}

  /*
     * Android 2.x needs to be able to check where the cursor is.  Android 4.x does not
     * 
     * (non-Javadoc)
     * @see android.app.Activity#onKeyDown(int, android.view.KeyEvent)
     */
    
    @Override
    public boolean onKeyDown(int keyCode, KeyEvent event)
    {
        //Determine if the focus is on the current view or not
        if (appView != null && appView.getFocusedChild() != null && (keyCode == KeyEvent.KEYCODE_BACK || keyCode == KeyEvent.KEYCODE_MENU)) {
                    return appView.onKeyDown(keyCode, event);
        }
        else
            return super.onKeyDown(keyCode, event);
    }
    
    

下面的代码可以响应后退按钮，并提示用户再次点击才退出。
如果3秒后没有点击则重新注册事件。

注意：window.plugins.ToastPlugin.show_short()是显示toast消息的插件!

代码：

// 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!');
}