android不继承FragmentActivity实现ViewPager+Fragment（标签的优化）

现在很多的ViewPager+Fragment都要Activity继承于FragmentActivity然后Adapter也是要继承于FragmentPagerAdapter实现的。然后我想想能不能直接用Activity跟PagerAdapter来实现。。。。当然了，也是项目需要。。接下来就是我的实现思路，其实就是改了一下PagerAdapter的instantiateItem函数就行

效果如下：（看代码，不要看图。。）

以下就是详细的代码：

import java.util.ArrayList;import com.example.androidtest.R;import android.app.Activity;import android.app.Fragment;import android.app.FragmentManager;import android.app.FragmentTransaction;import android.os.Bundle;import android.support.v4.view.PagerAdapter;import android.support.v4.view.ViewPager;import android.support.v4.view.ViewPager.OnPageChangeListener;import android.view.View;import android.view.ViewGroup;import android.widget.ImageView;public class MainViewPager extends Activity{private ViewPager pager;ArrayList<Fragment> mFragmentList = new ArrayList<Fragment>();ArrayList<String> titleContainer = new ArrayList<String>();private ImageView[] indicator_imgs = new ImageView[2];@SuppressWarnings("deprecation")@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.viewpager_main);pager = (ViewPager) this.findViewById(R.id.viewpager);//viewpager开始添加FragmentmFragmentList.add(new HomeFagment());mFragmentList.add(new SecondFragment());//设置ViewPager界面切换之间不会重新加载pager.setOffscreenPageLimit(mFragmentList.size());pager.setAdapter(new PagerAdapter() {//viewpager中的组件数量@Overridepublic int getCount() {return mFragmentList.size();}//每次滑动的时候生成的组件  重点在这！！！@Overridepublic Object instantiateItem(ViewGroup container, int position) {Fragment fragment = mFragmentList.get(position);if (!fragment.isAdded()) {//判断当前的Fragment是否存在FragmentManager fragmentManager = getFragmentManager();FragmentTransaction ft = fragmentManager.beginTransaction();ft.add(fragment, fragment.getClass().getSimpleName());ft.commitAllowingStateLoss();fragmentManager.executePendingTransactions();}if (fragment.getView().getParent() == null) {container.addView(fragment.getView());//把Fragment加到ViewPager里面}return fragment.getView();}@Overridepublic boolean isViewFromObject(View arg0, Object arg1) {return arg0 == arg1;}@Overridepublic int getItemPosition(Object object) {return super.getItemPosition(object);}@Overridepublic CharSequence getPageTitle(int position) {return titleContainer.get(position);}});pager.setOnPageChangeListener(new OnPageChangeListener() {@Overridepublic void onPageSelected(int arg0) {// 改变所有导航的背景图片为：未选中      for (int i = 0; i < indicator_imgs.length; i++) {        indicator_imgs[i].setBackgroundResource(R.drawable.home_off);      }      // 改变当前背景图片为：选中      indicator_imgs[arg0].setBackgroundResource(R.drawable.home_on);}@Overridepublic void onPageScrolled(int arg0, float arg1, int arg2) {}@Overridepublic void onPageScrollStateChanged(int arg0) {}});initIndicator();} /**   * 初始化引导图标   * 动态创建多个小圆点，然后组装到线性布局里   */  private void initIndicator(){        indicator_imgs[0] = (ImageView) findViewById(R.id.home_ic);    indicator_imgs[1] = (ImageView) findViewById(R.id.game_ic);    for (int i = 0; i < 2; i++) {      if (i == 0) { // 初始化第一个为选中状态        indicator_imgs[i].setBackgroundResource(R.drawable.home_on);      } else {        indicator_imgs[i].setBackgroundResource(R.drawable.home_off);      }    }  }}

HomeFragment的话也就是随意的添加一个布局而已

import android.app.Fragment;import android.os.Bundle;import android.view.LayoutInflater;import android.view.View;import android.view.ViewGroup;/** * 首页 * */public class HomeFagment extends Fragment{@Overridepublic View onCreateView(LayoutInflater inflater, ViewGroup container,Bundle savedInstanceState) {return inflater.inflate(R.layout.guide_item1, null);}}

布局：

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:orientation="vertical" >    <android.support.v4.view.ViewPager        android:id="@+id/viewpager"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:layout_weight="1" >    </android.support.v4.view.ViewPager>    <LinearLayout        android:id="@+id/indicator"        android:layout_width="match_parent"        android:layout_height="50dp"        android:orientation="horizontal" >        <LinearLayout            android:layout_width="match_parent"            android:layout_height="wrap_content"            android:layout_weight="1"            android:gravity="center_horizontal"            android:orientation="vertical" >            <ImageView                android:id="@+id/home_ic"                android:layout_width="wrap_content"                android:layout_height="wrap_content"                android:background="@drawable/home_on" />            <TextView                android:layout_width="wrap_content"                android:layout_height="wrap_content"                android:text="首页" />        </LinearLayout>        <LinearLayout            android:layout_width="match_parent"            android:layout_height="wrap_content"            android:layout_weight="1"            android:gravity="center_horizontal"            android:orientation="vertical" >            <ImageView                android:id="@+id/game_ic"                android:layout_width="wrap_content"                android:layout_height="wrap_content"                android:background="@drawable/game_off" />            <TextView                android:layout_width="wrap_content"                android:layout_height="wrap_content"                android:text="游戏" />        </LinearLayout>    </LinearLayout></LinearLayout>

然后标签页的话也就是在个ViewPager滑动的时候设置监听：

@Overridepublic void onPageSelected(int arg0) {// 改变所有导航的背景图片为：未选中      for (int i = 0; i < indicator_imgs.length; i++) {        indicator_imgs[i].setBackgroundResource(R.drawable.home_off);      }      // 改变当前背景图片为：选中      indicator_imgs[arg0].setBackgroundResource(R.drawable.home_on);}

这样的图片设置的话看起来不是很完美。。如果不是用一张图片的话可能要操作一大堆的逻辑关系，然后今天看到有一个用适配器的方法来更新底部的标题栏，这样在页面滑动的时候只要调用notifyDataSetChanged函数就可以了，当然了，用适配器的话肯定要配置适配器文件，但是配置完之后就方便了许多了。并且在以后如果底部的菜单栏发生变化的，修改起来也很方便，不需要去动配置文件啥的，只要改改一些代码。

以下就是改良版的。。。

MainActivity:

import java.util.ArrayList;import com.example.androidtest.R;import android.app.Activity;import android.app.Fragment;import android.app.FragmentManager;import android.app.FragmentTransaction;import android.os.Bundle;import android.support.v4.view.PagerAdapter;import android.support.v4.view.ViewPager;import android.support.v4.view.ViewPager.OnPageChangeListener;import android.view.View;import android.view.ViewGroup;public class MainViewPager extends Activity{private ViewPager pager;ArrayList<Fragment> mFragmentList = new ArrayList<Fragment>();ArrayList<String> titleContainer = new ArrayList<String>();private ArrayList<Tab> list = new ArrayList<Tab>();private TabView tabView;private TabAdapter mAdapter;@SuppressWarnings("deprecation")@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.viewpager_main);pager = (ViewPager) this.findViewById(R.id.viewpager);tabView = (TabView) findViewById(R.id.tab);//viewpager开始添加FragmentmFragmentList.add(new HomeFagment());mFragmentList.add(new SecondFragment());Tab tabHome = new Tab();//增加菜单项tabHome.setName("首页");tabHome.setIcon(R.drawable.home_icon);//这个地方设置的话不是单纯的一张图片 是一个drawable的select配置图片，这样才能在选中跟未选显示不同的图片list.add(tabHome);Tab tabGame = new Tab();tabGame.setName("游戏");tabGame.setIcon(R.drawable.game_icon);list.add(tabGame);mAdapter = new TabAdapter(MainViewPager.this, list);tabView.setNumColumns(list.size());//设置底部菜单栏的个数tabView.setAdapter(mAdapter);//设置ViewPager界面切换之间不会重新加载的页面数pager.setOffscreenPageLimit(mFragmentList.size());pager.setAdapter(new PagerAdapter() {//viewpager中的组件数量@Overridepublic int getCount() {return mFragmentList.size();}//每次滑动的时候生成的组件@Overridepublic Object instantiateItem(ViewGroup container, int position) {Fragment fragment = mFragmentList.get(position);if (!fragment.isAdded()) {//判断当前的Fragment是否存在FragmentManager fragmentManager = getFragmentManager();FragmentTransaction ft = fragmentManager.beginTransaction();ft.add(fragment, fragment.getClass().getSimpleName());ft.commitAllowingStateLoss();fragmentManager.executePendingTransactions();}if (fragment.getView().getParent() == null) {container.addView(fragment.getView());//把Fragment加到ViewPager里面}return fragment.getView();}@Overridepublic boolean isViewFromObject(View arg0, Object arg1) {return arg0 == arg1;}@Overridepublic int getItemPosition(Object object) {return super.getItemPosition(object);}@Overridepublic CharSequence getPageTitle(int position) {return titleContainer.get(position);}});pager.setOnPageChangeListener(new OnPageChangeListener() {@Overridepublic void onPageSelected(int arg0) {mAdapter.setSelectedPosition(arg0);//需要改动的话只要调用这两个代买，一个是设置选中的位置，一个是适配器更新mAdapter.notifyDataSetChanged();}@Overridepublic void onPageScrolled(int arg0, float arg1, int arg2) {}@Overridepublic void onPageScrollStateChanged(int arg0) {}});}}

TabAdapter：

import java.util.ArrayList;import com.example.androidtest.R;import android.content.Context;import android.graphics.Color;import android.view.LayoutInflater;import android.view.View;import android.view.ViewGroup;import android.widget.BaseAdapter;import android.widget.ImageView;import android.widget.RelativeLayout;import android.widget.TextView;public class TabAdapter extends BaseAdapter{private Context context;private ArrayList<Tab> list;public TabAdapter(Context context, ArrayList<Tab> list) {this.context = context;this.list = list;}private int selectedPosition = 0;// 选中的位置//设置选中位置public void setSelectedPosition(int position) {selectedPosition = position;}@Overridepublic View getView(int position, View convertView, ViewGroup parent) {ViewHold viewhold;if (convertView == null) {viewhold = new ViewHold();convertView = LayoutInflater.from(context).inflate(R.layout.tab_layout, parent, false);//加载单个tab的layoutTextView name = (TextView) convertView.findViewById(R.id.tv_name);//tab名称ImageView img = (ImageView) convertView.findViewById(R.id.iv_icon);//tab图标viewhold.name = name;viewhold.img = img;convertView.setTag(viewhold);} else {viewhold = (ViewHold) convertView.getTag();}viewhold.img.setBackgroundResource(list.get(position).getIcon());viewhold.name.setText(list.get(position).getName());if (position == selectedPosition) {//这个地方进行选中的颜色处理 选中的选项viewhold.name.setTextColor(Color.RED);viewhold.img.setSelected(true);//图片设置为选中状态} else {viewhold.name.setTextColor(Color.BLACK);viewhold.img.setSelected(false);}return convertView;}class ViewHold {TextView name;ImageView img;}@Overridepublic int getCount() {// TODO Auto-generated method stubreturn list.size();}@Overridepublic Object getItem(int arg0) {// TODO Auto-generated method stubreturn list.get(arg0);}@Overridepublic long getItemId(int arg0) {return arg0;}}

因为每个菜单项都是一个GridView子项，所以可以继承GridView然后实现自己的TabGridView，也可以直接用GridView。这个视情况而定了。TabGridView如下：

import android.content.Context;import android.util.AttributeSet;import android.view.KeyEvent;import android.view.MotionEvent;import android.widget.GridView;public class TabView extends GridView{public TabView(Context context, AttributeSet attrs, int defStyle) {super(context, attrs, defStyle);// TODO Auto-generated constructor stub}public TabView(Context context, AttributeSet attrs) {super(context, attrs);// TODO Auto-generated constructor stub}public TabView(Context context) {super(context);// TODO Auto-generated constructor stub}@Overridepublic boolean dispatchKeyEvent(KeyEvent event) {if(event.getAction() == MotionEvent.ACTION_MOVE){return true;//禁止Gridview进行滑动}return super.dispatchKeyEvent(event);}}

Tab：

/** * 菜单栏子项 */public class Tab {String name;//tab名称int icon;//tab图标public String getName() {return name;}public void setName(String name) {this.name = name;}public int getIcon() {return icon;}public void setIcon(int icon) {this.icon = icon;}}

还有Drawable，就拿一个home_icon来看看：

<?xml version="1.0" encoding="utf-8"?><selector xmlns:android="http://schemas.android.com/apk/res/android" >    <item android:drawable="@drawable/game_off" android:state_selected="false"></item>    <item android:drawable="@drawable/game_on" android:state_selected="true"></item></selector>

viewpager_main.xml:

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:orientation="vertical" >    <android.support.v4.view.ViewPager        android:id="@+id/viewpager"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:layout_weight="1" >    </android.support.v4.view.ViewPager>    <com.example.viewpager.TabView        android:id="@+id/tab"        android:layout_width="match_parent"        android:layout_height="wrap_content" /></LinearLayout>

tab子项的xml文件：tab_layout:

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:orientation="vertical" >    <ImageView         android:id="@+id/iv_icon"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:background="@drawable/home_off"        />    <TextView         android:id="@+id/tv_name"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="123"        /></LinearLayout>