ViewPager+Fragment滑动界面，并做延迟加载

本代码有缺陷，如果回到桌面后，资源被系统回收后会报错。
新文章： http://blog.csdn.net/q445697127/article/details/18352033

Activity继承FragmentActivity

package com.bitcare.activity;import java.util.ArrayList;import java.util.List;import android.graphics.Matrix;import android.support.v4.app.FragmentActivity;import android.support.v4.view.ViewPager;import android.support.v4.view.ViewPager.OnPageChangeListener;import android.util.DisplayMetrics;import android.view.Display;import android.view.View;import android.view.ViewGroup.LayoutParams;import android.view.WindowManager;import android.view.animation.Animation;import android.view.animation.TranslateAnimation;import android.widget.ImageButton;import android.widget.ImageView;import android.widget.TextView;import com.bitcare.adapter.FmtPagerAdapter;import com.bitcareV2.activity.R;import com.googlecode.androidannotations.annotations.AfterViews;import com.googlecode.androidannotations.annotations.Click;import com.googlecode.androidannotations.annotations.EActivity;import com.googlecode.androidannotations.annotations.NoTitle;import com.googlecode.androidannotations.annotations.ViewById;@EActivity(R.layout.activity_hospital)public class HospitalActivity extends FragmentActivity {@ViewByIdTextView tvTitle;@ViewByIdTextView tvProfiles, tvOffice, tvEvaluate;@ViewByIdImageButton ibLeft;@ViewByIdImageView ivBottomLine;@ViewByIdViewPager vpHospital;private List<BaseFragment> fragments;private int currIndex = 0;private int bottomLineWidth;private int offset = 0;@AfterViewsvoid initView() {tvTitle.setText("南昌大学第二附属医院");ibLeft.setVisibility(View.VISIBLE);InitWidth();InitViewPager();}private void InitWidth() {int screenWidth;// 屏幕宽度 如果是使用图片可以使用另一篇文章的宽度计算方法WindowManager windowManager = getWindowManager();Display display = windowManager.getDefaultDisplay();screenWidth = display.getWidth();bottomLineWidth = screenWidth / 3;LayoutParams layoutParams = ivBottomLine.getLayoutParams();layoutParams.width = bottomLineWidth;ivBottomLine.setLayoutParams(layoutParams);DisplayMetrics dm = new DisplayMetrics();getWindowManager().getDefaultDisplay().getMetrics(dm);int screenW = dm.widthPixels;// 获取分辨率宽度offset = (screenW / 3 - bottomLineWidth) / 2;// 计算偏移量Matrix matrix = new Matrix();matrix.postTranslate(offset, 0);ivBottomLine.setImageMatrix(matrix);// 设置动画初始位置}private HospitalProfilesFragment_ profilesFragment_;private HospitalOfficeFragment_ officeFragment_;private HospitalEvaluateFragment_ evaluateFragment_;private void InitViewPager() {fragments = new ArrayList<BaseFragment>();profilesFragment_ = new HospitalProfilesFragment_();officeFragment_ = new HospitalOfficeFragment_();evaluateFragment_ = new HospitalEvaluateFragment_();fragments.add(profilesFragment_);fragments.add(officeFragment_);fragments.add(evaluateFragment_);vpHospital.setAdapter(new FmtPagerAdapter(getSupportFragmentManager(), fragments));vpHospital.setOnPageChangeListener(changeListener);tvProfiles.setTextColor(getResources().getColor(R.color.black_txt));}@Clickvoid ibLeft() {finish();}@Clickvoid tvProfiles() {vpHospital.setCurrentItem(0);}@Clickvoid tvOffice() {vpHospital.setCurrentItem(1);}@Clickvoid tvEvaluate() {vpHospital.setCurrentItem(2);}OnPageChangeListener changeListener = new OnPageChangeListener() {@Overridepublic void onPageSelected(int arg0) {int one = offset * 2 + bottomLineWidth;// 页卡1 -> 页卡2 偏移量Animation animation = new TranslateAnimation(one * currIndex, one * arg0, 0, 0);// 显然这个比较简洁，只有一行代码。currIndex = arg0;animation.setFillAfter(true);animation.setDuration(100);ivBottomLine.startAnimation(animation);tvProfiles.setTextColor(getResources().getColor(R.color.gray_txt));tvOffice.setTextColor(getResources().getColor(R.color.gray_txt));tvEvaluate.setTextColor(getResources().getColor(R.color.gray_txt));switch (arg0) {case 0:tvProfiles.setTextColor(getResources().getColor(R.color.black_txt));break;case 1:tvOffice.setTextColor(getResources().getColor(R.color.black_txt));break;case 2:tvEvaluate.setTextColor(getResources().getColor(R.color.black_txt));break;}}@Overridepublic void onPageScrolled(int arg0, float arg1, int arg2) {}@Overridepublic void onPageScrollStateChanged(int arg0) {}};}

为了做延迟加载数据需要自定义一个BaseFragment类

package com.bitcare.activity;import android.support.v4.app.Fragment;public abstract class BaseFragment extends Fragment {/** * 显示页面数据 */public abstract void show();}

在写一个FragmentPagerAdapter类

package com.bitcare.adapter;import java.util.List;import android.support.v4.app.Fragment;import android.support.v4.app.FragmentManager;import android.support.v4.app.FragmentPagerAdapter;import android.view.ViewGroup;import com.bitcare.activity.BaseFragment;public class FmtPagerAdapter extends FragmentPagerAdapter {private List<BaseFragment> fragmentsList;        private FragmentManager fm;public FmtPagerAdapter(FragmentManager fm) {super(fm);                this.fm = fm;}public FmtPagerAdapter(FragmentManager fm, List<BaseFragment> fragments) {super(fm);this.fragmentsList = fragments;                this.fm = fm;}@Overridepublic int getCount() {return fragmentsList.size();}@Overridepublic Fragment getItem(int arg0) {return fragmentsList.get(arg0);} @Overridepublic void setPrimaryItem(ViewGroup container, int position, Object object) {//知道当前是第几页，但是每次滑动后可能会调用多次                //这个方法是重点super.setPrimaryItem(container, position, object);fragmentsList.get(position).show();}@Overridepublic int getItemPosition(Object object) {//加此方法可以使viewpager可以进行刷新return PagerAdapter.POSITION_NONE;}        //使用此方法刷新数据 每次都要NEW一个新的List，不然没有刷新效果 转至http://blog.sina.com.cn/s/blog_783ede03010173b4.htmlpublic void setFragments(ArrayList<Fragment> fragments) {if(this.fragments != null){FragmentTransaction ft = fm.beginTransaction();for(Fragment f:this.fragments){ft.remove(f);}ft.commit();ft=null;fm.executePendingTransactions();}this.fragments = fragments;notifyDataSetChanged();}@Overridepublic void destroyItem(ViewGroup container, int position, Object object) {// 注释自带的销毁方法防止页面被销毁                //这个方法是重点                // super.destroyItem(container, position, object);}}

给每个单独的页面继承BaseFragment即可，在show方法中实现调用数据的方法，但是注意的是每次滑动会多次调用show方法