代码示例

以下是一个简单的代码示例，演示了如何使用ViewPager和Fragment实现左右滑动切换页面的效果：

1. MainActivity.java

public class MainActivity extends AppCompatActivity {
    private ViewPager viewPager;
    private MyPagerAdapter pagerAdapter;
    private List<Fragment> fragmentList;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        initView();
        initData();
    }

    private void initView() {
        viewPager = findViewById(R.id.viewPager);
    }

    private void initData() {
        fragmentList = new ArrayList<>();
        fragmentList.add(new Fragment1());
        fragmentList.add(new Fragment2());
        fragmentList.add(new Fragment3());
        pagerAdapter = new MyPagerAdapter(getSupportFragmentManager(), fragmentList);
        viewPager.setAdapter(pagerAdapter);
        viewPager.setPageTransformer(true, new ZoomOutPageTransformer());
    }
}

2. MyPagerAdapter.java

public class MyPagerAdapter extends FragmentPagerAdapter {
    private List<Fragment> fragmentList;

    public MyPagerAdapter(FragmentManager fm, List<Fragment> fragmentList) {
        super(fm);
        this.fragmentList = fragmentList;
    }

    @Override
    public Fragment getItem(int position) {
        return fragmentList.get(position);
    }

    @Override
    public int getCount() {
        return fragmentList.size();
    }
}

3. ZoomOutPageTransformer.java

public class ZoomOutPageTransformer implements ViewPager.PageTransformer {
    private static final float MIN_SCALE = 0.85f;
    private static final float MIN_ALPHA = 0.5f;

    @Override
    public void transformPage(@NonNull View page, float position) {
        int pageWidth = page.getWidth();
        int pageHeight = page.getHeight();

        if (position < -1) { // 左侧不可见
            page.setAlpha(0);
        } else if (position <= 1) { // [-1,1]，页面正常滑动时
            float scaleFactor = Math.max(MIN_SCALE, 1 - Math.abs(position));
            float vertMargin = pageHeight * (1 - scaleFactor) / 2;
            float horzMargin = pageWidth * (1 - scaleFactor) / 2;
            if (position < 0) {
                page.setTranslationX(horzMargin - vertMargin / 2);
            } else {
                page.setTranslationX(-horzMargin + vertMargin / 2);
            }

            page.setScaleX(scaleFactor);
            page.setScaleY(scaleFactor);

            page.setAlpha(MIN_ALPHA + (scaleFactor - MIN_SCALE) / (1 - MIN_SCALE) * (1 - MIN_ALPHA));
        } else { // 右侧不可见
            page.setAlpha(0);
        }
    }
}

4. Fragment1.java, Fragment2.java, Fragment3.java

public class Fragment1 extends Fragment {
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment1, container, false);
        return view;
    }
}

public class Fragment2 extends Fragment {
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment2, container, false);
        return view;
    }
}

public class Fragment3 extends Fragment {
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment3, container, false);
        return view;
    }
}

这里的布局文件和其他代码都比较简单，就不一一列举了。需要注意的是，ZoomOutPageTransformer是用来实现页面滑动效果的，可以根据需要自行修改。