在Android中實現菜單功能有多種方法。
Options Menu：用戶按下menu Button時顯示的菜單。
Context Menu：用戶長時間按下屏幕，所顯示出來的菜單也稱為上下文菜單。
Submenu：子菜單。
但是有時候這些內置的菜單并不能滿足我們功能，這就需要自己自定義一種菜單。接下來我說的這種就是通過TabHost與RadioGroup結合完成的菜單。這也是很常用的一種底部菜單做法。先上圖：
Xml代碼
<?xml version="1.0" encoding="UTF-8"?> <TabHost android:id="@android:id/tabhost" android:layout_width="fill_parent" android:layout_height="fill_parent" xmlns:android="http://schemas.android.com/apk/res/android"> <LinearLayout android:orientation="vertical" android:layout_width="fill_parent" android:layout_height="fill_parent"> <FrameLayout android:id="@android:id/tabcontent" android:layout_width="fill_parent" android:layout_height="0.0dip" android:layout_weight="1.0" /> <TabWidget android:id="@android:id/tabs" android:visibility="gone" android:layout_width="fill_parent" android:layout_height="wrap_content" android:layout_weight="0.0" /> <RadioGroup android:gravity="center_vertical" android:layout_gravity="bottom" android:orientation="horizontal" android:id="@+id/main_radio" android:background="@drawable/maintab_toolbar_bg" android:layout_width="fill_parent" android:layout_height="wrap_content"> <RadioButton android:id="@+id/radio_button0" android:tag="radio_button0" android:layout_marginTop="2.0dip" android:text="@string/alarm" android:drawableTop="@drawable/icon_1" style="@style/main_tab_bottom" /> <RadioButton android:id="@+id/radio_button1" android:tag="radio_button1" android:layout_marginTop="2.0dip" android:text="@string/message" android:drawableTop="@drawable/icon_2" style="@style/main_tab_bottom" /> <RadioButton android:id="@+id/radio_button2" android:tag="radio_button2" android:layout_marginTop="2.0dip" android:text="@string/photo" android:drawableTop="@drawable/icon_3" style="@style/main_tab_bottom" /> <RadioButton android:id="@+id/radio_button3" android:tag="radio_button3" android:layout_marginTop="2.0dip" android:text="@string/music" android:drawableTop="@drawable/icon_4" style="@style/main_tab_bottom" /> <RadioButton android:id="@+id/radio_button4" android:tag="radio_button4" android:layout_marginTop="2.0dip" android:text="@string/setting" android:drawableTop="@drawable/icon_5" style="@style/main_tab_bottom" /> </RadioGroup> </LinearLayout> </TabHost>
需要注意的是，如果用TabHost這個控件，其中有幾個ID是必須這么寫的，android:id=”@android:id/tabhost ；android:id=”@android:id/tabcontent” ；android:id=”@android:id/tabs” ；之所以要這么寫是因為在TabHost這個類中。需要實例化上述這個ID的控件。看源碼：
在TabActivity中有么個方法：
@Override public void onContentChanged() { super.onContentChanged(); mTabHost = (TabHost) findViewById(com.android.internal.R.id.tabhost); if (mTabHost == null) { throw new RuntimeException( "Your content must have a TabHost whose id attribute is " + "'android.R.id.tabhost'"); } mTabHost.setup(getLocalActivityManager()); } private void ensureTabHost() { if (mTabHost == null) { this.setContentView(com.android.internal.R.layout.tab_content); } } 當內容發生改變時它會調用這個方法，來更新列表或者其他視圖，而這個方法中需要實例化TabHost，所以必須通過ID為tabhost實例化。
再看看TabHost這個類中
public void setup() { mTabWidget = (TabWidget) findViewById(com.android.internal.R.id.tabs); if (mTabWidget == null) { throw new RuntimeException( "Your TabHost must have a TabWidget whose id attribute is 'android.R.id.tabs'"); } // KeyListener to attach to all tabs. Detects non-navigation keys // and relays them to the tab content. mTabKeyListener = new OnKeyListener() { public boolean onKey(View v, int keyCode, KeyEvent event) { switch (keyCode) { case KeyEvent.KEYCODE_DPAD_CENTER: case KeyEvent.KEYCODE_DPAD_LEFT: case KeyEvent.KEYCODE_DPAD_RIGHT: case KeyEvent.KEYCODE_DPAD_UP: case KeyEvent.KEYCODE_DPAD_DOWN: case KeyEvent.KEYCODE_ENTER: return false; } mTabContent.requestFocus(View.FOCUS_FORWARD); return mTabContent.dispatchKeyEvent(event); } }; mTabWidget.setTabSelectionListener(new TabWidget.OnTabSelectionChanged() { public void onTabSelectionChanged(int tabIndex, boolean clicked) { setCurrentTab(tabIndex); if (clicked) { mTabContent.requestFocus(View.FOCUS_FORWARD); } } }); mTabContent = (FrameLayout) findViewById(com.android.internal.R.id.tabcontent); if (mTabContent == null) { throw new RuntimeException( "Your TabHost must have a FrameLayout whose id attribute is " + "'android.R.id.tabcontent'"); } } 這個方法，是在增加選項卡之前由系統調用。在這個方法中需要通過tabs 這個ID實例化一個TabWidget，通過tabcontent這個ID實例化一個FrameLayout，用來放置選項卡內容。所以這兩個ID也是固定的。
在上述布局文件中隱藏了系統默認的Widget，取而代之的是帶有圖片的Button。
看一下主要代碼：
package com.iteye.androidtoast; import android.app.TabActivity; import android.content.Intent; import android.os.Bundle; import android.widget.RadioGroup; import android.widget.RadioGroup.OnCheckedChangeListener; import android.widget.TabHost; public class MainActivity extends TabActivity implements OnCheckedChangeListener{ /** Called when the activity is first created. */ private TabHost mHost; private RadioGroup radioderGroup; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.maintabs); //實例化TabHost mHost=this.getTabHost(); //添加選項卡 mHost.addTab(mHost.newTabSpec("ONE").setIndicator("ONE") .setContent(new Intent(this,OneActivity.class))); mHost.addTab(mHost.newTabSpec("TWO").setIndicator("TWO") .setContent(new Intent(this,TwoActivity.class))); mHost.addTab(mHost.newTabSpec("THREE").setIndicator("THREE") .setContent(new Intent(this,ThreeActivity.class))); mHost.addTab(mHost.newTabSpec("FOUR").setIndicator("FOUR") .setContent(new Intent(this,FourActivity.class))); mHost.addTab(mHost.newTabSpec("FIVE").setIndicator("FIVE") .setContent(new Intent(this,FiveActivity.class))); radioderGroup = (RadioGroup) findViewById(R.id.main_radio); radioderGroup.setOnCheckedChangeListener(this); } @Override public void onCheckedChanged(RadioGroup group, int checkedId) { switch(checkedId){ case R.id.radio_button0: mHost.setCurrentTabByTag("ONE"); break; case R.id.radio_button1: mHost.setCurrentTabByTag("TWO"); break; case R.id.radio_button2: mHost.setCurrentTabByTag("THREE"); break; case R.id.radio_button3: mHost.setCurrentTabByTag("FOUR"); break; case R.id.radio_button4: mHost.setCurrentTabByTag("FIVE"); break; } } } 以上就是本文的全部內容，希望對大家的學習有所幫助，也希望大家多多支持武林網。
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