以下是我想要实现的目标： 我有ActioBar，我在ActionBar上有一个名为Login的菜单项。单击此登录菜单项时，它会在操作栏中添加一个新选项卡，并在父活动的容器内加载带有login_layout的片段。如果我单击任何其他选项卡而不是登录选项卡消失。它只能重新出现，如果再次单击登录菜单项。 一旦登录成功，我想将菜单项的标题更改为Log Out.And现在将Login菜单项的标题设置为Log out，如果我点击它，它不应该在actiobar上添加任何标签，因为用户已经登录。
我有一个工作代码到用户已成功登录的部分，因此他的登录菜单项的标题已更改为注销。但我遇到的问题是现在当用户点击退出时仍然添加选项卡并显示登录片段。
执行此操作的Easyway是menuItem.getTitle（）并根据menuItem的当前标题限制操作。但我不认为这是完成此操作的好方法。所以现在我尝试使用标志“loginMenuItemFlag”并试图解决问题，但没有成功。我已经能够使其工作到它更改登录菜单项的标题以注销，但当用户点击注销时，它再次添加/显示登录选项卡我不想要。任何人都可以告诉我，我做错了什么，并指出我正确的方向。谢谢。
下面是我创建menuItem并添加Tabs，删除Tabs，更改标志，根据标志值更改menuitem标题的类的代码：
public class HomeActivity extends SherlockFragmentActivity {
String mCurFilter;
static boolean flag,loginMenuItemFlag;
LoginScreenFragment loginFragment;
HomeFragment homeFragment;
CartFragment cartFragment;
MyFragment myFragment;
FragmentTransaction ft, ft2;
ActionBar actionbar;
MenuItem loginItem;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.home);
// ActionBar
actionbar = getSupportActionBar();
actionbar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
homeFragment = new HomeFragment();
cartFragment = new CartFragment();
myFragment = new MyFragment();
loginFragment = new LoginScreenFragment();
actionbar.addTab(actionbar.newTab()
.setText(R.string.home_fragment_title)
.setTabListener(new MyTabsListener(homeFragment))
.setTag("HOME"));
actionbar.addTab(actionbar.newTab()
.setText(R.string.cart_fragment_title)
.setTabListener(new MyTabsListener(cartFragment))
.setTag("CART"));
actionbar.addTab(actionbar.newTab()
.setText(R.string.my_fragment_title)
.setTabListener(new MyTabsListener(myFragment))
.setTag("MYFragment"));
if (!flag) {
ft = getSupportFragmentManager().beginTransaction();
ft.add(R.id.fragment_container, homeFragment);
ft.show(homeFragment);
ft.add(R.id.fragment_container, cartFragment);
ft.hide(cartFragment);
ft.add(R.id.fragment_container, myFragment);
ft.hide(myFragment);
ft.add(R.id.fragment_container, loginFragment);
ft.hide(loginFragment);
ft.commit();
flag = true;
} else {
}
}
@Override
protected void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
outState.putInt("tab", getSupportActionBar()
.getSelectedNavigationIndex());
}
@Override
public boolean onCreateOptionsMenu(final Menu menu) {
loginItem = menu.add(R.string.menuitem_login);
loginItem.setTitle(R.string.menuitem_login);
loginItem.setShowAsAction(MenuItem.SHOW_AS_ACTION_ALWAYS);
loginItem.setOnMenuItemClickListener(new OnMenuItemClickListener() {
@Override
public boolean onMenuItemClick(MenuItem item) {
if(!loginMenuItemFlag){
Tab loginTab = actionbar.newTab()
.setText(R.string.login_fragment_title)
.setTabListener(new MyTabsListener(loginFragment))
.setTag(R.string.login_label);
actionbar.addTab(loginTab);
actionbar.selectTab(loginTab);
loginItem.setVisible(false);
loginItem.setTitle(R.string.login_label);
//loginMenuItemFlag = false;
}
else{
loginItem.setTitle(R.string.menuitem_login);
//loginMenuItemFlag = false;
}
return false;
}
});
return true;
}
// removes TAB at a specified position
public void deleteTabAt(int tabPosition) {
actionbar = getSupportActionBar();
actionbar.removeTabAt(tabPosition);
}
//setting Login menu Item to visible when Login tab has been removed from the tabs
public void setLoginMenuItemVisible() {
loginItem.setVisible(true);
}
public void changeLoginMenuFlag(){
loginMenuItemFlag = false;
}
//chaging Log In menu item to Log out upon successful Log in
public void changeLoginMenutItem(){
if(!loginMenuItemFlag){
loginItem.setTitle(R.string.menuitem_logout);
loginMenuItemFlag = false;
}else{
loginItem.setTitle(R.string.menuitem_login);
loginMenuItemFlag= true;
}
}
class MyTabsListener implements ActionBar.TabListener {
public SherlockFragment fragment;
public MyTabsListener(SherlockFragment fragment) {
this.fragment = fragment;
}
@Override
public void onTabReselected(Tab tab, FragmentTransaction ft) {
System.out.println("TabReselected " + tab.getPosition());
}
@Override
public void onTabSelected(Tab tab, FragmentTransaction ft) {
System.out.println("TabSelected " + tab.getPosition());
ft.show(this.fragment);
}
@Override
public void onTabUnselected(Tab tab, FragmentTransaction ft) {
System.out.println("TabUnselected " + tab.getPosition());
ft.hide(this.fragment);
//making check if the unselected tab was Login tab(located at tab position 3),if it was a login tab than we remove it from ActionBar
if (tab.getPosition() == 3) {
deleteTabAt(tab.getPosition());
setLoginMenuItemVisible();
}
}
}
}
以下是LoginFragment中执行登录操作的代码。以下是在登录尝试后执行的代码段。
@Override
public void sendResponse(String response) {
pd.dismiss();
System.out.println("Response in the callback: " + response);
if (response != null) {
FragmentActivity homeActivity = getActivity();
if (homeActivity instanceof HomeActivity) {
((HomeActivity) homeActivity).deleteTabAt(3);
((HomeActivity) homeActivity).changeLoginMenuFlag();
((HomeActivity) homeActivity).changeLoginMenutItem();
((HomeActivity) homeActivity).setLoginMenuItemVisible();
Toast.makeText(getActivity(), "Login Successful!",
Toast.LENGTH_LONG).show();
}
} else {
Toast.makeText(getActivity(), "Login failed,Please try again...",
Toast.LENGTH_LONG).show();
}
}
谢谢。
答案 0 :(得分：0)
使用onPrepareOptionsMenu()更改菜单，onOptionsItemSelected处理菜单项点击：
private boolean mLoggedIn;
private MenuItem mItemLogIn;
private MenuItem mItemLogOut;
@Override
public boolean onCreateOptionsMenu(Menu menu) {
mItemLogIn = menu.add("Log In");
mItemLogOut = menu.add("Log Out");
//---set more properties--
return super.onCreateOptionsMenu(menu);
}
@Override
public boolean onPrepareOptionsMenu(Menu menu) {
mItemLogIn.setVisible(!mLoggedIn);
mItemLogOut.setVisible(mLoggedIn);
return super.onPrepareOptionsMenu(menu);
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
if(item.equals(mItemLogIn)){
//--login--
mLoggedIn = true;
invalidateOptionsMenu();
}else if(item.equals(mItemLogOut)){
//--log out--
mLoggedIn = false;
invalidateOptionsMenu();
}
return super.onOptionsItemSelected(item);
}