今天又学了一点很重要的知识.就是在应用程序中设置全局变量.
先来说说为什么要设置全局变量吧.举一个例子,通过是否登录,来设置TabHost的状态.如果登录,则显示PM模块,否则不显示PM模块.
如图:
好了,我们要怎么弄呢?
我们有可能在任何一个页面登录,登录后就要去通知TabHost改变状态.比如,我在MoreActivity中的个人中心页面(PersonCenterActivity)登录.当登录成功后,我按返回键,则MainTabActivity中的TabHost就要有PM模块了.
看思路:
首先,我们要清楚android的生命周期,MainTabActivity与MoreActivity的什么关系呢?我们点击"更多"按钮时,MainTabActivity结束了吗?现在是运行在MoreActivity上面吗?
我们可以实验一下:
在MainTabActivity的onResume()方法中加入 Log.i("TAG","mainTab-->resume");在MoreActivity的onResume()方法中加入Log.i("TAG","More-->resume");
当我们Lanucher时,看到只打印了mainTab-->resume
.点击"更多"按钮时只打印more-->resume.当点击MoreActivity中的个人中心进入个人中心页面.点击返回按钮时,奇怪的事发生了,
它执行了两个Resume();
而对我们有用的当然是存放TabHost的MainTabActivity的Resume方法了.
说了这么多,要进入主题了.我们要怎么改变TabHost的项呢?
一个好的办法就是建一个全局的类AppRuntime来设置它是否要显示.
看代码:
public class AppRuntime
{
public static boolean Must_Refresh
=true;//设置是否要更新Tab
public static boolean isMust_Refresh() { return
Must_Refresh; } public static void setMust_Refresh(boolean
must_Refresh) { Must_Refresh = must_Refresh;
}
}
判断是否登录当然也放里面.(这边是用判断Load到的数据是否为空来判断的)
protected static int m_UserID = -1;
protected static ExtJSONObject m_UserData;
public static int getUserID()
{
if (AppRuntime.m_UserID <= 0)
{
ExtJSONObject oUserData = AppRuntime.getUserData();
if (oUserData != null)
{
AppRuntime.m_UserID = oUserData.optInt("uid");
}
}
return AppRuntime.m_UserID;
}
public static void setUserID(int p_UserID)
{
AppRuntime.m_UserID = p_UserID;
}
public static ExtJSONObject getUserData()
{
return AppRuntime.m_UserData;
}
public static void setUserData(ExtJSONObject p_UserData)
{
AppRuntime.m_UserID = -1;
AppRuntime.m_UserData = p_UserData;
}
好了.现在返回去看MainTabActivity里怎么处理:
我们把创建TabHost放在OnResume中,而不放在OnCreate中,原因我刚刚写的.
@Override
protected void onResume()
{
super.onResume();
Log.i("TAG","mainTab-->resume");
if (AppRuntime.isMust_Refresh())
{
mUserJsonData =
AppRuntime.getUserData();
if
(mUserJsonData != null)
{
m_IsLogin =
true;
}else
{
m_IsLogin =
false;
}
TabHost tabHost = this.getTabHost();
tabHost.setCurrentTab(0);
tabHost.clearAllTabs();
tabHost.setup();
TabWidget widget = tabHost.getTabWidget();
widget.setDividerDrawable(R.drawable.split);
String sNewest = "最新";
int iNewestId = R.drawable.newesta;
View newestView = createTabItemView(sNewest, iNewestId);
TabSpec oTabSpec = tabHost.newTabSpec(sNewest);
oTabSpec.setIndicator(newestView);
oTabSpec.setContent(new Intent(this,
NewestListActivity.class));
tabHost.addTab(oTabSpec);
String sPlate = "板块";
int iPlateId = R.drawable.platea;
View plateView = createTabItemView(sPlate, iPlateId);
tabHost.addTab(tabHost.newTabSpec(sPlate).setIndicator(plateView)
.setContent(new Intent(this, GroupActivity.class)));
String sAttention = "关注";
int iAttentionId = R.drawable.attentiona;
View attentionView = createTabItemView(sAttention,
iAttentionId);
tabHost.addTab(tabHost.newTabSpec(sAttention)
.setIndicator(attentionView)
.setContent(new Intent(this,
FavoriteListActivity.class)));
if
(m_IsLogin)
{
String sPM = "PM";
int iPMId = R.drawable.pma;
View PMView = createTabItemView(sPM, iPMId);
tabHost.addTab(tabHost.newTabSpec(sPM).setIndicator(PMView)
.setContent(new Intent(this, PMActivity.class)));
}
sMore = "更多";
int iMoreId = R.drawable.morea;
View moreView = createTabItemView(sMore, iMoreId);
tabHost.addTab(tabHost.newTabSpec(sMore).setIndicator(moreView)
.setContent(new Intent(this, MoreActivity.class)));
// 设置TAB 背景和改变TAB背景
for (int i = 0; i < widget.getTabCount();
i++)
{
View view = widget.getChildTabViewAt(i);
view.setBackgroundResource(R.drawable.tabback);
}
widget.setDividerDrawable(R.drawable.split);
widget.requestLayout();
int oIndex = Integer.parseInt(INDEX);
tabHost.setCurrentTab(oIndex);
AppRuntime.setMust_Refresh(false);
}
}
看红色的字,是不是有点冲动?
当OnResume方法执行完了must_refresh
的值永远都是false.放在AppRuntime中,直到我们去改变它.
我们来改变它吧
下面的代码是在PersonCenterActivity中的:
private AlertDialog.Builder LoginDialog()
{
AlertDialog.Builder dlg = new AlertDialog.Builder(
PersonCenterActivity.this);
dlg.setTitle("登录框");
dlg.setView(DialogView);
dialog = dlg.show();
btn_Pos.setOnClickListener(new OnClickListener()
{
@Override
public void onClick(View v)
{
mAccount = tName.getText().toString();
mPwd = tPwd.getText().toString();
if ("".equals(mAccount.trim()) ||
"".equals(mPwd.trim()))
{
PersonCenterActivity.this.showToast("账号与密码不能为空");
}
else
{
ActionLogin oActionLogin = new ActionLogin(mAccount,
mPwd);
mResult = oActionLogin.doAction();
if (mResult == 1)
{
ActionUserDetail oLoadUserDetail = new
ActionUserDetail();
oLoadUserDetail.doAction();
ExtJSONObject object = oLoadUserDetail
.getJSONData();
AppRuntime.setUserData(object);
AppRuntime.setMust_Refresh(true);
PersonCenterActivity.this.showToast("登入成功");
PersonCenterActivity.this.loadData();
dialog.dismiss();
}
else if (mResult == -10)
{
PersonCenterActivity.this.showToast("请检查账号");
return;
}
else if (mResult == -1)
{
PersonCenterActivity.this.showToast("登录失败");
}
}
}
});
btn_Nag.setOnClickListener(new OnClickListener()
{
@Override
public void onClick(View v)
{
finish();
}
});
return dlg;
}
看到了吗?这里就又把must_refresh设置回了true.它就可以执行了.这里就是login的状态了.就可以显示出PM模块了.