android之ViewPager的使用

package com.stevenhu.vpt; import java.util.ArrayList; import android.app.Activity; import android.app.Fragment; import android.content.Context; import android.os.Bundle; import android.support.v13.app.FragmentPagerAdapter; import android.support.v4.view.ViewPager; import android.support.v4.view.ViewPager.OnPageChangeListener; import android.util.Log; import android.view.KeyEvent; import android.view.View; import android.view.View.OnClickListener; import android.view.ViewGroup; import android.widget.Button; import android.widget.ImageView; import android.widget.LinearLayout; public class MainActivity extends Activity implements OnClickListener { private final static String TAG = "MainActivity"; private ViewPager mViewPager; private ViewPagerAdapter mViewPagerAdapter; private LinearLayout mIndicatorGroup; //定义指示翻页图标数组 private ImageView[] mIndicatorImage; private Button mBackButton, mNextButton; //定义当前在第几页 private int mCurrentPage = 0; /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); mViewPager = (ViewPager)findViewById(R.id.viewpager); //创建自定义的ViewPagerAdapter对象 mViewPagerAdapter = new ViewPagerAdapter(this, mViewPager); //添加Fragment mViewPagerAdapter.addFragment(FirstFragmentPage.class, null); mViewPagerAdapter.addFragment(SecondFragmentPage.class, null); mViewPagerAdapter.addFragment(ThirdFragmentPage.class, null); mViewPagerAdapter.addFragment(ForthFragmentPage.class, null); //获取指示器图标所在界面布局对象 mIndicatorGroup = (LinearLayout)findViewById(R.id.indicator_group); mIndicatorImage = new ImageView[mViewPagerAdapter.getCount()]; mBackButton = (Button)findViewById(R.id.back_button); mNextButton = (Button)findViewById(R.id.next_button); mBackButton.setOnClickListener(this); mNextButton.setOnClickListener(this); initIndicator(); } //初始化指示器，实现随着创建页数的增加从而添加相应个数的指示图标。 private void initIndicator() { for (int i = 0; i < mViewPagerAdapter.getCount(); i ++) { ImageView imageView = new ImageView(this); imageView.setLayoutParams(new ViewGroup.LayoutParams(20,20)); imageView.setPadding(20, 0, 20, 0); if (i == 0) { imageView.setBackgroundResource(R.drawable.page_indicator_focused); } else { imageView.setBackgroundResource(R.drawable.page_indicator); } mIndicatorImage[i] = imageView; mIndicatorGroup.addView(mIndicatorImage[i]); } } /*通过监听按钮实现向上或向下翻页。 * 当然，由于是使用ViewPager，所以用户也可以通过滑动屏幕来实现翻页 */ @Override public void onClick(View v) { if(v.getId() == R.id.back_button){ //当前为第一页则直接返回不做处理 if(mCurrentPage <= 0) { return; } //返回上一页 mViewPager.setCurrentItem(mCurrentPage - 1, true); } else { //当前页为最后一页 if(mCurrentPage >= mViewPagerAdapter.getCount() - 1) { this.finish(); } //返回下一页 mViewPager.setCurrentItem(mCurrentPage + 1, true); } } @Override public boolean onKeyDown(int keyCode, KeyEvent event) { // TODO Auto-generated method stub if (keyCode == KeyEvent.KEYCODE_BACK) { return true; } return super.onKeyDown(keyCode, event); } /*通过调用FragmentPagerAdapter的addFragment方法实现添加Fragment类型的class对象 * 通过调用FragmentPagerAdapter的getItem方法实现取出Fragment类型对象 */ private class ViewPagerAdapter extends FragmentPagerAdapter implements OnPageChangeListener { private Context mContext; private ViewPager mAdpterViewPager = null; private ArrayList<TabInfo> mTabList = new ArrayList<TabInfo>(); public ViewPagerAdapter(Activity activity, ViewPager viewPager) { super(activity.getFragmentManager()); mContext = activity; mAdpterViewPager = viewPager; //为ViewPager添加适配器，适配器为当前的ViewPagerAdapter mAdpterViewPager.setAdapter(this); //为ViewPager设置翻页改变监听器 mAdpterViewPager.setOnPageChangeListener(this); } @Override public void onPageScrollStateChanged(int arg0) { // TODO Auto-generated method stub Log.d(TAG, "onPageScrollStateChanged-->arg0-->" + arg0); } @Override public void onPageScrolled(int arg0, float arg1, int arg2) { // TODO Auto-generated method stub Log.d(TAG, "onPageScrolled-->arg0-->" + arg0 + "-->arg1-->" + arg1 + "-->arg2-->" + arg2); } //当前选中的页面，position表示在第几页，0为第一页 @Override public void onPageSelected(int position) { // TODO Auto-generated method stub Log.d(TAG, "onPageSelected-->position-->" + position); mCurrentPage = position; for (int i = 0; i < mIndicatorImage.length; i ++) { if (i == position) { //若为当前页面，指示器显示为聚焦图片 mIndicatorImage[i].setBackgroundResource(R.drawable.page_indicator_focused); } else { mIndicatorImage[i].setBackgroundResource(R.drawable.page_indicator); } } //若当前页面为最后一页，则下一页按钮显示为完成按钮 if(position == getCount() - 1){ mNextButton.setText(R.string.finish); }else{ mNextButton.setText(R.string.next); } } @Override public Fragment getItem(int position) { // TODO Auto-generated method stub TabInfo tab = mTabList.get(position); if (tab.fragment == null) { //创建Fragment对象 tab.fragment = Fragment.instantiate(mContext, tab.clazz.getName(), tab.bundle); } return tab.fragment; } @Override public int getCount() { // TODO Auto-generated method stub return mTabList.size(); } public void addFragment(Class<?> clazz, Bundle bundle) { TabInfo tabInfo = new TabInfo(clazz, bundle); mTabList.add(tabInfo); //通知数据改变 notifyDataSetChanged(); } private final class TabInfo { private final Class<?> clazz; private final Bundle bundle; Fragment fragment; TabInfo(Class<?> clazz, Bundle bundle) { this.clazz = clazz; this.bundle = bundle; } } } }