3 Screen的定制
Screen可以说是App Inventor2开发的最基础组件了，其对应的源码在/appinventor/components/src/com/google/appinventor/components/runtime/Form.java
使用App Inventor2开发的APP，都有两个功能菜单：Stopthis application和About thisapplication，这两个菜单使用的字符串都是英文，为方便使用，修改为中文，同时增加了一个更新版本的功能菜单。
在Form.java中的修改如下：
//创建功能菜单
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// This procedure is called only once. To change the items dynamically
// we would use onPrepareOptionsMenu.
super.onCreateOptionsMenu(menu);
// add the menu items
// Comment out the next line if we don't want the exit button
addAboutInfoToMenu(menu);
//添加更新版本的功能菜单
addUpdateToMenu(menu);
addExitButtonToMenu(menu);
for (OnCreateOptionsMenuListener onCreateOptionsMenuListener :onCreateOptionsMenuListeners) {
onCreateOptionsMenuListener.onCreateOptionsMenu(menu);
}
return true;
}
//关于功能菜单
public void addAboutInfoToMenu(Menu menu) {
//1表示此菜单在菜单列表中的排在第1个，就是索引值为1
MenuItem aboutAppItem = menu.add(Menu.NONE, Menu.NONE, 1, //2,
//"About this application")
"关于")
.setOnMenuItemClickListener(new OnMenuItemClickListener() {
public boolean onMenuItemClick(MenuItem item) {
//点击菜单调用的函数
showAboutApplicationNotification();
return true;
}
});
//功能菜单icon图标
aboutAppItem.setIcon(android.R.drawable.sym_def_app_icon);
}
//更新版本功能菜单
public void addUpdateToMenu(Menu menu) {
MenuItem updateAppItem = menu.add(Menu.NONE, Menu.NONE, 2,
//"About this application")
"更新版本")
.setOnMenuItemClickListener(new OnMenuItemClickListener() {
public boolean onMenuItemClick(MenuItem item) {
showVersionInfo();
return true;
}
});
updateAppItem.setIcon(android.R.drawable.ic_dialog_info);
}
//退出应用的功能菜单
public void addExitButtonToMenu(Menu menu) {
MenuItem stopApplicationItem = menu.add(Menu.NONE, Menu.NONE, 3,//Menu.FIRST,
//"Stop this application")
"退出")
.setOnMenuItemClickListener(new OnMenuItemClickListener() {
public boolean onMenuItemClick(MenuItem item) {
showExitApplicationNotification();
return true;
}
});
stopApplicationItem.setIcon(android.R.drawable.ic_notification_clear_all);
}
private voidshowExitApplicationNotification() {
//String title = "Stop application?";
//String message = "Stop this application and exit? You'll need torelaunch " +
// "the application to useit again.";
//String positiveButton = "Stop and exit";
//String negativeButton = "Don't stop";
String title = "提示";
String message = "确定要退出应用？";
String positiveButton = "确定";
String negativeButton = "取消";
// These runnables are passed to twoButtonAlert. They perform the corresponding actions
// when the button is pressed. Here there's nothing to do for "don't stop" and cancel
Runnable stopApplication = new Runnable() {public void run (){closeApplicationFromMenu();}};
Runnable doNothing = new Runnable () {public void run() {}};
Notifier.twoButtonDialog(
this,
message,
title,
positiveButton,
negativeButton,
false, // cancelable is false
stopApplication,
doNothing,
doNothing);
}
private String yandexTranslateTagline = "";
void setYandexTranslateTagline(){
yandexTranslateTagline = "<p><small>Languagetranslation powered by Yandex.Translate</small></p>";
}
private void showAboutApplicationNotification() {
//String title = "About this app";
String title = "关于";
String MITtagline = "<p><small><em>Invented withMIT AppInventor<br>appinventor.mit.edu</em></small></p>";
// Users can hide the taglines by including an HTML open comment <!--in the about screen message
//String message = aboutScreen + MITtagline + yandexTranslateTagline;
String message = aboutScreen;
message = message.replaceAll("\\n", "<br>");// Allow for line breaks in the string.
//String buttonText ="Got it";
String buttonText ="确定";
Notifier.oneButtonAlert(this, message, title, buttonText);
}
private void showVersionInfo() {
Intent intent =new Intent(Intent.ACTION_VIEW);
//这里的网址就是提供新版本供用户下载的网址，调用设备上安装的浏览器打开此网页
intent.setData(Uri.parse("http://xxx.xxx.xxx"));
this.startActivity(intent);
}
最终的实现效果如下：
在应用的底部会显示3个中文功能菜单。
点击退出功能菜单，显示如下中文提示框：