android底部菜单应用

痛定思痛。 2022-06-17 03:53 237阅读 0赞

原文地址:[http://www.iteye.com/topic/1116261][http_www.iteye.com_topic_1116261]

在android中实现菜单功能有多种方法。

**Options Menu：**用户按下menu Button时显示的菜单。

**Context Menu：**用户长时间按下屏幕，所显示出来的菜单也称为上下文菜单。

**Submenu：**子菜单。

但是有时候这些内置的菜单并不能满足我们功能，这就需要自己自定义一种菜单。接下来我说的这种就是通过TabHost与RadioGroup结合完成的菜单。这也是很常用的一种底部菜单做法。先上图：

![0_1322449960pA3O.gif][]

首先看布局文件：

<?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这个控件，其中有几个ID是必须这么写的，android:id="@android:id/tabhost   ；android:id="@android:id/tabcontent" ；android:id="@android:id/tabs" ；之所以要这么写是因为在TabHost这个类中。需要实例化上述这个ID的控件。看源码：

在TabActivity中有么个方法：

@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);
            }
        }

当内容发生改变时它会调用这个方法，来更新列表或者其他视图，而这个方法中需要实例化TabHost，所以必须通过ID为tabhost实例化。

再看看TabHost这个类中，

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'");
            }
        }

这个方法，是在增加选项卡之前由系统调用。在这个方法中需要通过tabs 这个ID实例化一个TabWidget，通过tabcontent这个ID实例化一个FrameLayout，用来放置选项卡内容。所以这两个ID也是固定的。

在上述布局文件中隐藏了系统默认的Widget，取而代之的是带有图片的Button。

看一下主要代码：

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);
            //实例化TabHost
            mHost=this.getTabHost();
            
            //添加选项卡
            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;
    		}		
    	}
    }

[http_www.iteye.com_topic_1116261]: http://www.iteye.com/topic/1116261
[0_1322449960pA3O.gif]: /images/20220617/c3576ded015e42ed9922938068226664.png