一、ViewPager使用
（1）ViewPager常用方法
- setAdapter()：设置适配器
- setCurrentItem()：跳转到特定的页面
- setOffscreenPageLimit()：设置缓存的页面个数,默认是 1
- addOnPageChangeListener()：设置页面滑动时的监听器
- setPageTransformer()：设置页面切换时的动画效果
- setPageMargin()：设置不同页面之间的间隔
- setPageMarginDrawable()：设置不同页面间隔之间的装饰图，需要同时设置setPageMargin()
- getPageTitle()：设置标题名称
- getCurrentItem()：返回当前显示的页码
（2）PagerAdapter类
public class MyPagerAdapter extends PagerAdapter {
private Context context;
private List<Integer> list;
public MyPagerAdapter(Context context, List<Integer> list) {
this.context = context;
this.list = list;
}
//显示多少个页面
@Override
public int getCount() {
if (list != null && list.size() > 0) {
return list.size();
} else {
return 0;
}
}
//判断初始化返回的Object是不是一个View对象
@Override
public boolean isViewFromObject(@NonNull View view, @NonNull Object object) {
return view == object;
}
//初始化显示的条目对象
@NonNull
@Override
public Object instantiateItem(@NonNull ViewGroup container, int position) {
ImageView imageView = new ImageView(context);
imageView.setImageDrawable(context.getResources().getDrawable(list.get(position)));
container.addView(imageView);
return imageView;
}
//销毁条目对象
@Override
public void destroyItem(@NonNull ViewGroup container, int position, @NonNull Object object) {
container.removeView((View) object);
}
}
- 在代码中调用
ViewPager view_pager = findViewById(R.id.view_pager);
List<Integer> list = new ArrayList<>();
list.add(R.drawable.ic_launcher);
list.add(R.drawable.ic_launcher);
list.add(R.drawable.ic_launcher);
list.add(R.drawable.ic_launcher);
MyPagerAdapter adapter = new MyPagerAdapter(this, list);
view_pager.setAdapter(adapter);
adapter.notifyDataSetChanged()//刷新界面
（3）FragmentPagerAdapter与FragmentStatePagerAdapter实现
public class MyFragmentPagerAdapter extends FragmentPagerAdapter {
private List<Fragment> list = new ArrayList<>();
@SuppressLint("WrongConstant")
public MyFragmentPagerAdapter(@NonNull FragmentManager fm) {
super(fm, 0);
list.add(new PagerFragment());
list.add(new PagerFragment());
list.add(new PagerFragment());
list.add(new PagerFragment());
}
//显示的fragment对象
@NonNull
@Override
public Fragment getItem(int position) {
return list.get(position);
}
//ViewPager页面的数量
@Override
public int getCount() {
return list.size();
}
}
- 在代码中实现调用
MyFragmentPagerAdapter myFragmentPagerAdapter = new MyFragmentPagerAdapter(getSupportFragmentManager());
view_pager.setAdapter(myFragmentPagerAdapter);
- FragmentPagerAdapter对于不再需要的fragment，FragmentPagerAdapter则选择调用事务的detach() 方法，而非remove()方法来处理它。
- FragmentPagerAdapter只是销毁了fragment的视图，但仍将fragment实例保留在FragmentManager中。因此， FragmentPagerAdapter创建的fragment永远不会被销毁。
- 使用FragmentStatePagerAdapter会销毁掉不需要的fragment。事务提交后，可将fragment从activity的FragmentManager中彻底移除。
（4）ViewPager + TableLayout使用
public class MyPagerAdapter extends PagerAdapter {
private Context context;
private List<Integer> list;
private String[] titles = new String[]{"标题一", "标题二", "标题三", "标题四"};
public MyPagerAdapter(Context context, List<Integer> list) {
this.context = context;
this.list = list;
}
//显示多少个页面
@Override
public int getCount() {
if (list != null && list.size() > 0) {
return list.size();
} else {
return 0;
}
}
//判断初始化返回的Object是不是一个View对象
@Override
public boolean isViewFromObject(@NonNull View view, @NonNull Object object) {
return view == object;
}
//初始化显示的条目对象
@SuppressLint("SetTextI18n")
@NonNull
@Override
public Object instantiateItem(@NonNull ViewGroup container, int position) {
ImageView imageView = new ImageView(context);
imageView.setImageDrawable(context.getResources().getDrawable(list.get(position)));
container.addView(imageView);
return imageView;
}
//销毁条目对象
@Override
public void destroyItem(@NonNull ViewGroup container, int position, @NonNull Object object) {
container.removeView((View) object);
}
//触发销毁和重建
@Override
public int getItemPosition(@NonNull Object object) {
return POSITION_NONE;
}
//设置标题
@Nullable
@Override
public CharSequence getPageTitle(int position) {
return titles[position];
}
}
- 代码中调用
ViewPager view_pager = findViewById(R.id.view_pager);
tableLayout.setupWithViewPager(view_pager);
tableLayout.setTabMode(TabLayout.MODE_SCROLLABLE);//设置摆动方式
二、ViewPager实现首页轮播图效果
（1）在MyPagerAdapter实现显示banner图片、标题、点击事件
public class MyPagerAdapter extends PagerAdapter {
private Context context;
private List<Integer> list;
private String[] titles = new String[]{"标题一", "标题二", "标题三", "标题四"};
public MyPagerAdapter(Context context, List<Integer> list) {
this.context = context;
this.list = list;
}
//显示多少个页面
@Override
public int getCount() {
if (list != null && list.size() > 0) {
return list.size();
} else {
return 0;
}
}
//判断初始化返回的Object是不是一个View对象
@Override
public boolean isViewFromObject(@NonNull View view, @NonNull Object object) {
return view == object;
}
//初始化显示的条目对象
@SuppressLint("SetTextI18n")
@NonNull
@Override
public Object instantiateItem(@NonNull ViewGroup container, int position) {
View view = LayoutInflater.from(context).inflate(R.layout.item_pager, container, false);
ImageView imageView = view.findViewById(R.id.banner_image);
TextView textView = view.findViewById(R.id.banner_title);
imageView.setImageDrawable(context.getResources().getDrawable(list.get(position)));
textView.setText("轮播图标题内容------" + position);
view.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
bannerClickListener.onBannerClick(v, position);
}
});
container.addView(view);
return view;
}
//销毁条目对象
@Override
public void destroyItem(@NonNull ViewGroup container, int position, @NonNull Object object) {
container.removeView((View) object);
}
//触发销毁和重建
@Override
public int getItemPosition(@NonNull Object object) {
return POSITION_NONE;
}
//设置标题
@Nullable
@Override
public CharSequence getPageTitle(int position) {
return titles[position];
}
private BannerClickListener bannerClickListener;
public interface BannerClickListener {
void onBannerClick(View view, int position);
}
//通过实现接口处理点击事件
public void setBannerClickListener(BannerClickListener bannerClickListener) {
this.bannerClickListener = bannerClickListener;
}
}
（2）在Activity中代码实现
public class MainActivity extends AppCompatActivity {
private TabLayout tableLayout;
private ViewPager view_pager;
private LinearLayout linearLayout;
private List<Integer> list;
private List<ImageView> roundList;
private MyPagerAdapter adapter;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
initView();
initData();
//适配adapter
view_pager.setAdapter(adapter);
//设置标题
tableLayout.setupWithViewPager(view_pager);
//设置摆动方式
tableLayout.setTabMode(TabLayout.MODE_SCROLLABLE);
//设置滑动监听
view_pager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
//当前页面发生滑动时调用
@Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
}
//页面滑动结束，选定页面时调用
@Override
public void onPageSelected(int position) {
for (int i = 0; i < roundList.size(); i++) {
if (position % roundList.size() == i) {
roundList.get(i).setImageResource(R.drawable.ic_launcher);
} else {
roundList.get(i).setImageResource(R.drawable.ic_launcher_s);
}
}
}
//当滑动状态改变时调用
@Override
public void onPageScrollStateChanged(int state) {
}
});
//设置轮播图点击事件监听
adapter.setBannerClickListener(new MyPagerAdapter.BannerClickListener() {
@Override
public void onBannerClick(View view, int position) {
}
});
}
private void initView() {
tableLayout = findViewById(R.id.table_layout);
view_pager = findViewById(R.id.view_pager);
linearLayout = findViewById(R.id.linearLayout);
}
private void initData() {
//添加轮播图图片
list = new ArrayList<>();
list.add(R.mipmap.ic_launcher);
list.add(R.mipmap.ic_launcher);
list.add(R.mipmap.ic_launcher);
list.add(R.mipmap.ic_launcher);
adapter = new MyPagerAdapter(this, list);
//添加轮播图圆点
roundList = new ArrayList<>();
for (int i = 0; i < 4; i++) {
ImageView imageView = new ImageView(this);
if (i == 0) {
imageView.setImageResource(R.drawable.ic_launcher);
} else {
imageView.setImageResource(R.drawable.ic_launcher_s);
}
LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(16, 16);
params.setMargins(5, 0, 5, 0);
linearLayout.addView(imageView, params);
roundList.add(imageView);
}
}
@Override
protected void onDestroy() {
super.onDestroy();
}
}
