js怎么监听安卓返回键

Question

集成phonegap，对返回键做事件重写。    <script type="text/javascript" charset="utf-8" src="cordova.js"></script>
    <script type="text/javascript" charset="utf-8" src="Toast.js"></script>
// 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.toast.showShortBottom('再点击一下返回，将退出私募通。');
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.toast.showShortTop('click Menu Button');
}
//搜索键
function eventSearchButton(){
window.plugins.toast.showShortTop('click Search Button!');
}