Android原生專案實現雙擊返回鍵退出應用，是十分簡單的，新增如下程式碼即可實現：

//記錄按鍵時間
    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){
            // 點選間隔大於兩秒，做出提示
            Toast.makeText(getApplicationContext(), "再按一次退出應用", Toast.LENGTH_SHORT).show();
            exitTime = System.currentTimeMillis();
        }else{
            finish();
            System.exit(0);
        }
    }
 

解決辦法：在app.js的config中新增如下程式碼：

// 等待載入PhoneGap
document.addEventListener("deviceready", onDeviceReady, false); 
// PhoneGap載入完畢
function onDeviceReady() {
//按鈕事件
document.addEventListener("backbutton", eventBackButton, false); //返回鍵
document.addEventListener("menubutton", eventMenuButton, false); //選單鍵
document.addEventListener("searchbutton", eventSearchButton, false); //搜尋鍵
}
 
//返回鍵
function eventBackButton(){
//confirm("再點選一次退出!");
window.plugins.ToastPlugin.show_short('再點選一次退出!');
document.removeEventListener("backbutton", eventBackButton, false); //登出返回鍵
    //3秒後重新註冊
    var intervalID = window.setInterval(
        function() {
           window.clearInterval(intervalID);
           document.addEventListener("backbutton", eventBackButton, false); //返回鍵
        },
        3000
   );
}
//選單鍵
function eventMenuButton(){
    window.plugins.ToastPlugin.show_short('點選了 選單 按鈕!');
}
//搜尋鍵
function eventSearchButton(){
    window.plugins.ToastPlugin.show_short('點選了 搜尋 按鈕!');
}
 

cordova plugin add https://github.com/EddyVerbruggen/Toast-PhoneGap-Plugin.git