给TabHost加上拖动效果

先说一下第一个示例，我做了一个可以拖动但是无法停留的效果，这个效果的实现是在TabHost的setCurrentTab方法里面加上动画，所以得自己写一个TabHost继承系统的TabHost并重写setCurrentTab方法。

那么我就把这个效果的代码给大家贴出来

package com.hwh.tab;import android.content.Context;import android.content.res.Resources;import android.util.AttributeSet;import android.util.DisplayMetrics;import android.view.animation.Animation;import android.view.animation.TranslateAnimation;import android.widget.TabHost;/* * 自定义TabHost，使tab切换的时候有动画效果 */public class CustomTabHost extends TabHost {private Animation slideLeftIn;private Animation slideLeftOut;private Animation slideRightIn;private Animation slideRightOut;private int tabCount;// tab页总数private int device_x; //屏幕宽public CustomTabHost(Context context, AttributeSet attrs) {super(context, attrs);Resources resources = getResources();        DisplayMetrics metrics=resources.getDisplayMetrics();        device_x=metrics.widthPixels;        initAnima();}private void initAnima() {slideLeftIn=new TranslateAnimation(device_x, 0, 1, 1);slideLeftIn.setDuration(500);slideRightIn=new TranslateAnimation(-device_x,0,1,1);slideRightIn.setDuration(500);slideLeftOut=new TranslateAnimation(0,-device_x,1,1);slideLeftOut.setDuration(500);slideRightOut=new TranslateAnimation(0,device_x,1,1);slideRightOut.setDuration(500);}public void setDevice_X(int device_x){this.device_x=device_x;initAnima();}public int getTabCount() {return tabCount;}@Overridepublic void addTab(TabSpec tabSpec) {tabCount++;super.addTab(tabSpec);}@Overridepublic void setCurrentTab(int index) {// index为要切换到的tab页索引，currentTabIndex为现在要当前tab页的索引int currentTabIndex = getCurrentTab();// 设置当前tab页退出时的动画if (null != getCurrentView()) {// 第一次进入MainActivity时，getCurrentView()取得的值为空if (currentTabIndex == (tabCount - 1) && index == 0) {// 处理边界滑动getCurrentView().startAnimation(slideLeftOut);} else if (currentTabIndex == 0 && index == (tabCount - 1)) {// 处理边界滑动getCurrentView().startAnimation(slideRightOut);} else if (index > currentTabIndex) {// 非边界情况下从右往左fleepgetCurrentView().startAnimation(slideLeftOut);} else if (index < currentTabIndex) {// 非边界情况下从左往右fleepgetCurrentView().startAnimation(slideRightOut);}}super.setCurrentTab(index);// 设置即将显示的tab页的动画if (currentTabIndex == (tabCount - 1) && index == 0) {// 处理边界滑动getCurrentView().startAnimation(slideLeftIn);} else if (currentTabIndex == 0 && index == (tabCount - 1)) {// 处理边界滑动getCurrentView().startAnimation(slideRightIn);} else if (index > currentTabIndex) {// 非边界情况下从右往左fleepgetCurrentView().startAnimation(slideLeftIn);} else if (index < currentTabIndex) {// 非边界情况下从左往右fleepgetCurrentView().startAnimation(slideRightIn);}}}

这个思路是从网上找到的。TabHost的切换动画有了，怎么实现拖动呢。这个就很简单了，在Activity里重写OnTouth方法

@Override    public boolean onTouchEvent(MotionEvent event) {    switch (event.getAction()) {case MotionEvent.ACTION_DOWN:start_x=(int) event.getX();break;case MotionEvent.ACTION_UP:end_x=(int) event.getX();int len=end_x-start_x;if(len<0){if(Math.abs(len)>device_x/2){index+=1;}//向右}if(len>0){if(Math.abs(len)>device_x/2){index-=1;}}if(index==count){index=count-1;}if(index<0){index=0;}tabHost.setCurrentTab(index);break;}    return false;    }

这样就可以拖动了，但是没办法实现像ViewPager那样可以拖动一半的效果。

基于这个原因，我就想能不能把ViewPager和TabHost合并呢，但是有个问题，ViewPager要的是个View，而TabHost里面是Activity，怎么把Activity里的View给得到呢。

一个重要的类：LocalActivityManager，此类有个方法可以得到activity的View，使用startActivity(id, intent).getDecorView()即可得到，其中id可以随意写，intent就是对应activity的意图。思路说完了，下面把代码贴出来。

显示布局文件：

<?xml version="1.0" encoding="utf-8"?><TabHost xmlns:android="http://schemas.android.com/apk/res/android"    android:id="@android:id/tabhost"    android:layout_width="fill_parent"    android:layout_height="fill_parent" >    <LinearLayout        android:id="@+id/linearLayout1"        android:layout_width="fill_parent"        android:layout_height="fill_parent"        android:orientation="vertical" >        <TabWidget            android:id="@android:id/tabs"            android:layout_width="fill_parent"            android:layout_height="wrap_content" >        </TabWidget>    <android.support.v4.view.ViewPager        android:id="@+id/vPager"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_gravity="center"        android:layout_weight="1.0"        android:background="#000000"        android:flipInterval="30"        android:persistentDrawingCache="animation" />        <FrameLayout            android:id="@android:id/tabcontent"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:visibility="gone" >        </FrameLayout>    </LinearLayout></TabHost>

Java代码：

package com.hwh.demo;import java.util.ArrayList;import java.util.List;import android.app.LocalActivityManager;import android.app.TabActivity;import android.content.Context;import android.content.Intent;import android.graphics.BitmapFactory;import android.graphics.Matrix;import android.os.Bundle;import android.os.Parcelable;import android.support.v4.view.PagerAdapter;import android.support.v4.view.ViewPager;import android.support.v4.view.ViewPager.OnPageChangeListener;import android.util.DisplayMetrics;import android.util.Log;import android.view.View;import android.view.View.OnClickListener;import android.view.Window;import android.view.animation.Animation;import android.view.animation.TranslateAnimation;import android.widget.ImageView;import android.widget.TabHost;import android.widget.TabHost.OnTabChangeListener;import android.widget.TextView;public class DemoActivity extends TabActivity {        //页卡内容        private ViewPager mPager;        // Tab页面列表        private List<View> listViews;         // 当前页卡编号        private LocalActivityManager manager = null;        private final Context context = DemoActivity.this;        private TabHost mTabHost;    /** Called when the activity is first created. */    @Override    public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);                                requestWindowFeature(Window.FEATURE_NO_TITLE);        setContentView(R.layout.main);                mTabHost =  getTabHost();          mTabHost.addTab(mTabHost.newTabSpec("0").setIndicator(                  "正在听").setContent(                  new Intent(this, AActivity.class)));                 mTabHost.addTab(mTabHost.newTabSpec("1").setIndicator(                  "本地听").setContent(                  new Intent(this, BActivity.class)));                 mTabHost.addTab(mTabHost.newTabSpec("2").setIndicator(                  "网络听").setContent(                  new Intent(this, CActivity.class)));                  mTabHost.setCurrentTab(0);                  //tabhost改变同样改变ViewPager的内容        mTabHost.setOnTabChangedListener(new OnTabChangeListener() {@Overridepublic void onTabChanged(String tabId) {mPager.setCurrentItem(Integer.parseInt(tabId));}});                manager = new LocalActivityManager(this, true);        manager.dispatchCreate(savedInstanceState);                InitViewPager();    }            /**         * 初始化ViewPager         */        private void InitViewPager() {                mPager = (ViewPager) findViewById(R.id.vPager);                listViews = new ArrayList<View>();                MyPagerAdapter mpAdapter = new MyPagerAdapter(listViews);                Intent intent = new Intent(context, AActivity.class);                listViews.add(getView("A", intent));                Intent intent2 = new Intent(context, BActivity.class);                listViews.add(getView("B", intent2));                Intent intent3 = new Intent(context, CActivity.class);                listViews.add(getView("C", intent3));                mPager.setAdapter(mpAdapter);                mPager.setCurrentItem(0);                mPager.setOnPageChangeListener(new MyOnPageChangeListener());        }                        /**         * ViewPager适配器         */        public class MyPagerAdapter extends PagerAdapter {                public List<View> mListViews;                public MyPagerAdapter(List<View> mListViews) {                        this.mListViews = mListViews;                }                @Override                public void destroyItem(View arg0, int arg1, Object arg2) {                        ((ViewPager) arg0).removeView(mListViews.get(arg1));                }                @Override                public void finishUpdate(View arg0) {                }                @Override                public int getCount() {                        return mListViews.size();                }                @Override                public Object instantiateItem(View arg0, int arg1) {                        ((ViewPager) arg0).addView(mListViews.get(arg1), 0);                        return mListViews.get(arg1);                }                @Override                public boolean isViewFromObject(View arg0, Object arg1) {                        return arg0 == (arg1);                }                @Override                public void restoreState(Parcelable arg0, ClassLoader arg1) {                }                @Override                public Parcelable saveState() {                        return null;                }                @Override                public void startUpdate(View arg0) {                }        }        /**         * 页卡切换监听，ViewPager改变同样改变TabHost内容         */        public class MyOnPageChangeListener implements OnPageChangeListener {                @Override                public void onPageSelected(int arg0) {                        switch (arg0) {                        case 0:                                mTabHost.setCurrentTab(0);                                  break;                        case 1:                                mTabHost.setCurrentTab(1);                                break;                        case 2:                                mTabHost.setCurrentTab(2);                                break;                        }                }                @Override                public void onPageScrolled(int arg0, float arg1, int arg2) {                }                @Override                public void onPageScrollStateChanged(int arg0) {                }        }                private View getView(String id,Intent intent)        {                return manager.startActivity(id, intent).getDecorView();        }}

到此结束，如有不足之处请指出。