妙用TabHost——(转载)

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.