前段时间写了篇关于Fragment的文章,介绍了基础的概念,用静态和动态的方式加载Fragment Xamarin Android Fragment的两种加载方式。下面的这个例子介绍xamarin android fragment实现简单的底部导航栏。
效果图和项目结构
效果图：
项目结构：
实现步骤
主要的流程就是：点击不同的菜单加载对应的fragment出来，同时菜单icon切换和菜单文字颜色也响应变化,是否选中是通过selected来判断的。我们需要写以下几个资源文件，文字颜色的变化，菜单图片的变化。
step1：底部菜单资源文件
文字颜色变化资源： tab__menu_text.xml
<?xml version="1.0" encoding="utf-8" ?> <selector xmlns:android="http://schemas.android.com/apk/res/android"> <item android:color="@color/color_primary" android:state_selected="true"></item> <item android:color="@color/color_808080"></item> </selector>菜单图片的变化资源：tab_menu_chat.xml 、tab_menu_more.xml、tab_menu_contracts.xml
<?xml version="1.0" encoding="utf-8" ?> <selector xmlns:android="http://schemas.android.com/apk/res/android"> <item android:drawable="@drawable/more_selected" android:state_selected="true"></item> <item android:drawable="@drawable/more"></item> </selector>三个都是一样的样式。
step2：MainActivity布局文件 Main.axml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="@+id/relativelayout1"
android:background="@color/color_primary"
android:fitsSystemWindows="true">
<RelativeLayout
android:id="@+id/ly_top_bar"
android:layout_width="match_parent"
android:layout_height="48dp"
android:background="@color/color_primary">
<TextView
android:id="@+id/txt_topbar"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_centerInParent="true"
android:gravity="center"
android:textSize="18sp"
android:textColor="@color/color_white"
android:text="信息" />
<View
android:layout_width="match_parent"
android:layout_height="2px"
android:background="@color/div_white"
android:layout_alignParentBottom="true" />
</RelativeLayout>
<LinearLayout
android:id="@+id/ly_tab_bar"
android:layout_width="match_parent"
android:layout_height="58dp"
android:layout_alignParentBottom="true"
android:background="@color/bg_white"
android:orientation="horizontal">
<TextView
android:id="@+id/txt_chat"
style="@style/tabText"
android:drawableTop="@drawable/tab_menu_chat"
android:text="我的"/>
<TextView
android:id="@+id/txt_more"
style="@style/tabText"
android:drawableTop="@drawable/tab_menu_more"
android:text="更多"/>
<TextView
android:id="@+id/txt_contacts"
style="@style/tabText"
android:drawableTop="@drawable/tab_menu_contacts"
android:text="联系人"/>
</LinearLayout>
<View
android:id="@+id/div_tab_bar"
android:layout_width="match_parent"
android:layout_height="2px"
android:background="@color/div_white"
android:layout_above="@id/ly_tab_bar" />
<FrameLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_below="@id/ly_top_bar"
android:layout_above="@id/div_tab_bar"
android:id="@+id/ly_content" />
</RelativeLayout>
关于布局采用的相对布局分为三个部分：头部标题、中间Fragment的位置、底部导航栏。关于根布局文件中fitsSystemWindows属性是为了配合透明状态栏使用的，有兴趣的可以看看前几天的写的那篇文章。底部导航栏文字很多属性都是一模一样的，所以提出来，写一个style。使用widget属性让其各占1/3。文字样式tabText如下：
<?xml version="1.0" encoding="utf-8" ?> <selector xmlns:android="http://schemas.android.com/apk/res/android"> <item android:color="@color/color_primary" android:state_selected="true"></item> <item android:color="@color/color_808080"></item> </selector>
step3：Fragment布局文件继承Fragment的类MyFragment
fg_content.xml:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="@color/bg_white">
<TextView
android:id="@+id/txt_content"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:gravity="center"
android:text="呵呵"
android:textColor="@color/color_primary"
android:textSize="20sp" />
</LinearLayout>
MyFragment.cs
public class MyFragment : Fragment
{
private string content { get; set; }
public MyFragment(string content)
{
this.content = content;
}
public override View OnCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
{
View view = inflater.Inflate(Resource.Layout.fg_content, container, false);
TextView txt_content = (TextView)view.FindViewById(Resource.Id.txt_content);
txt_content.Text = content;
return view;
}
}
step3：MainActivity.cs
[Activity(Label = "FragmentDemo", MainLauncher = true, Icon = "@drawable/icon", Theme = "@android:style/Theme.Light.NoTitleBar")]
public class MainActivity : Activity
{
private TextView txt_chat;
private TextView txt_contacts;
private TextView txt_more;
private FrameLayout ly_content;
private MyFragment fg1, fg2, fg3;
private FragmentManager fManager;
protected override void OnCreate(Bundle bundle)
{
base.OnCreate(bundle);
SetContentView(Resource.Layout.Main);
ly_content = (FrameLayout)FindViewById(Resource.Id.ly_content);
MyFragment fg = new MyFragment("第一个fragment");
txt_chat = (TextView)FindViewById(Resource.Id.txt_chat);
txt_contacts = (TextView)FindViewById(Resource.Id.txt_contacts);
txt_more = (TextView)FindViewById(Resource.Id.txt_more);
bindViews();
txt_chat.PerformClick();
}
//ui组件初始化与事件绑定
private void bindViews()
{
txt_chat.Click += (s, e) => { onClick(txt_chat); };
txt_contacts.Click += delegate { onClick(txt_contacts); };
txt_more.Click += delegate { onClick(txt_more); };
}
//隐藏所有Fragment
private void hideAllFragment(FragmentTransaction fragmentTransaction)
{
if (fg1 != null) fragmentTransaction.Hide(fg1);
if (fg2 != null) fragmentTransaction.Hide(fg2);
if (fg3 != null) fragmentTransaction.Hide(fg3);
}
//重置所有文本的选中状态
private void setSelected()
{
txt_chat.Selected =false;
txt_contacts.Selected = false;
txt_more.Selected = false;
}
//单击事件
public void onClick(View v)
{
FragmentTransaction fTransaction = FragmentManager.BeginTransaction();
hideAllFragment(fTransaction);
switch (v.Id)
{
case Resource.Id.txt_chat:
setSelected();
txt_chat.Selected = true;
if (fg1 == null)
{
fg1 = new MyFragment("聊天Fragment");
fTransaction.Add(Resource.Id.ly_content, fg1);
}
else{fTransaction.Show(fg1);}break;
case Resource.Id.txt_contacts:
setSelected();
txt_contacts.Selected = true;
if (fg2 == null)
{
fg2 = new MyFragment("联系人Fragment");
fTransaction.Add(Resource.Id.ly_content, fg2);
}
else{fTransaction.Show(fg2);}
break;
case Resource.Id.txt_more:
setSelected();
txt_more.Selected = true;
if (fg3 == null)
{
fg3 = new MyFragment("MoreFragment");
fTransaction.Add(Resource.Id.ly_content, fg3);
}else{fTransaction.Show(fg3);}break;
}
fTransaction.Commit();
}
}
关于继承的主题使用的android自带的主题Theme.Light.NoTitle，当然你也可以引入v7兼容包，继承AppcompatActivity，使用兼容包主题step4：沉浸式状态栏
这个随手也实现一下吧，挺简单的。Main.axml中根布局中已经设置了属性fitsSystemWindows，兼容android4.4 和安定肉ID5.* ,我们在用代码设置状态栏透明就可以。有关的介绍可以参考 Xamarin android沉浸式状态栏
if (Build.VERSION.SdkInt >= Build.VERSION_CODES.Kitkat)
{
//透明状态栏
Window.AddFlags(WindowManagerFlags.TranslucentStatus);
//透明导航栏
Window.AddFlags(WindowManagerFlags.TranslucentNavigation);
}