Android ViewPager2 可垂直左右滑动使用【java】
作者：互联网
ViewPager2位于androidx包下，也就是它不像ViewPager一样被内置在系统源码中。因此，使用ViewPager2需要额外的添加依赖库。另外，android support中不包含ViewPager，也就是要使用ViewPager2必须迁移到androidx才可以。
添加依赖
dependencies {
implementation "androidx.viewpager2:viewpager2:1.0.0"
}
布局：
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<androidx.viewpager2.widget.ViewPager2
android:id="@+id/view_pager"
android:layout_width="match_parent"
android:layout_height="280dp"
app:layout_constraintBottom_toTopOf="@+id/btn"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<Button
android:id="@+id/btn"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="切换"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintHorizontal_bias="1.0"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="1.0" />
</androidx.constraintlayout.widget.ConstraintLayout>
适配器：
package com.loaderman.viewpage2;
import android.graphics.Color;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
import androidx.annotation.NonNull;
import androidx.recyclerview.widget.RecyclerView;
import java.util.ArrayList;
import java.util.List;
public class MyAdapter extends RecyclerView.Adapter<PagerViewHolder> {
List<String> list= new ArrayList<>();
String[] colors = {"#FF00CC","#41F1E5","#8D41F1","#FF99CC"};
public MyAdapter() {
list.add("1");
list.add("2");
list.add("3");
list.add("4");
}
@NonNull
@Override
public PagerViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
View itemView = LayoutInflater.from(parent.getContext()).inflate(R.layout.item_page, parent, false);
return new PagerViewHolder(itemView);
}
@Override
public void onBindViewHolder(@NonNull PagerViewHolder holder, int position) {
holder.tv.setText(list.get(position));
holder.tv.setBackgroundColor(Color.parseColor(colors[position]));
}
@Override
public int getItemCount() {
return list.size();
}
}
class PagerViewHolder extends RecyclerView.ViewHolder{
public TextView tv;
public PagerViewHolder(@NonNull View itemView) {
super(itemView);
tv=itemView.findViewById(R.id.tv_text);
}
}
item_page.xml
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:gravity="center">
<TextView
android:id="@+id/tv_text"
android:background="@color/colorPrimaryDark"
android:layout_width="match_parent"
android:layout_height="280dp"
android:gravity="center"
android:textColor="#ffffff"
android:textSize="22sp" />
</LinearLayout>
FragmentStateAdapter
package com.loaderman.viewpage2;
import androidx.annotation.NonNull;
import androidx.fragment.app.Fragment;
import androidx.fragment.app.FragmentActivity;
import androidx.viewpager2.adapter.FragmentStateAdapter;
public class MyFragmentStateAdapter extends FragmentStateAdapter{
public MyFragmentStateAdapter(@NonNull FragmentActivity fragmentActivity) {
super(fragmentActivity);
}
@NonNull
@Override
public Fragment createFragment(int position) {
return FragmentFactory.getFragment(position);
}
@Override
public int getItemCount() {
return 4;
}
}
页面缩放
package com.loaderman.viewpage2;
import android.view.View;
import androidx.annotation.NonNull;
import androidx.viewpager2.widget.ViewPager2;
//页面缩放
public class ScaleInTransformer implements ViewPager2.PageTransformer {
final float DEFAULT_MIN_SCALE = 0.85f;
final float DEFAULT_CENTER = 0.5f;
final float mMinScale = DEFAULT_MIN_SCALE;
@Override
public void transformPage(@NonNull View view, float position) {
view.setElevation(-Math.abs(position));
float pageWidth = view.getWidth();
float pageHeight = view.getHeight();
view.setPivotY((pageHeight / 2));
view.setPivotX ((pageWidth / 2));
if (position < -1) {
view.setScaleX(mMinScale);
view.setScaleY(mMinScale);
view.setPivotX(pageWidth);
} else if (position <= 1) {
if (position < 0) {
float scaleFactor = (1 + position) * (1 - mMinScale) + mMinScale;
view.setScaleX(scaleFactor);
view.setScaleY(scaleFactor);
view.setPivotX(pageWidth * (DEFAULT_CENTER + DEFAULT_CENTER * -position));
} else {
float scaleFactor = (1 - position) * (1 - mMinScale) + mMinScale;
view.setScaleX(scaleFactor);
view.setScaleY(scaleFactor);
view.setPivotX(pageWidth * ((1 - position) * DEFAULT_CENTER));
}
} else {
view.setPivotX(0f);
view.setScaleX(mMinScale);
view.setScaleY(mMinScale);
}
}
}
主页面：
package com.loaderman.viewpage2;
import androidx.appcompat.app.AppCompatActivity;
import androidx.viewpager2.widget.CompositePageTransformer;
import androidx.viewpager2.widget.MarginPageTransformer;
import androidx.viewpager2.widget.ViewPager2;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
/*
ViewPager2与ViewPager同是继承自ViewGrop，但是ViewPager2被声明成了final。
意味着我们不可能再像ViewPager一样通过继承来修改ViewPager2的代码。
FragmentStatePagerAdapter被FragmentStateAdapter 替代PagerAdapter被RecyclerView.Adapter替代addPageChangeListener被registerOnPageChangeCallback。
我们知道ViewPager的addPageChangeListener接收的是一个OnPageChangeListener的接口，
而这个接口中有三个方法，当想要监听页面变化时需要重写这三个方法。
而ViewPager2的registerOnPageChangeCallback方法接收的是一个叫OnPageChangeCallback的抽象类，
因此我们可以选择性的重写需要的方法即可。移除了setPargeMargin方法。
* */
public class MainActivity extends AppCompatActivity {
private ViewPager2 viewPager2;
private Button btn;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
viewPager2 = findViewById(R.id.view_pager);
btn = findViewById(R.id.btn);
// MyAdapter myAdapter = new MyAdapter();
//竖直滑动
// viewPager2.setOrientation(ViewPager2.ORIENTATION_VERTICAL);
// viewPager2.setAdapter(myAdapter);
// 页面滑动事件监听
viewPager2.registerOnPageChangeCallback(new ViewPager2.OnPageChangeCallback() {
@Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
super.onPageScrolled(position, positionOffset, positionOffsetPixels);
System.out.println("onPageScrolled" + +position);
}
@Override
public void onPageSelected(int position) {
super.onPageSelected(position);
System.out.println("onPageSelected " + position);
}
@Override
public void onPageScrollStateChanged(int state) {
super.onPageScrollStateChanged(state);
System.out.println("onPageScrollStateChanged state-->" + +state);
}
});
// 设置页面间距
viewPager2.setPageTransformer(new MarginPageTransformer((int) getResources().getDimension(R.dimen.dp10)));
//按钮点击可以模拟用户滑动
btn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
//禁止ViewPager2的滑动
viewPager2.setUserInputEnabled(false);
//拖拽,按钮点击可以模拟用户滑动
viewPager2.beginFakeDrag();
if (viewPager2.fakeDragBy(-310f))
viewPager2.endFakeDrag();
}
});
// 设置页面切换动画
CompositePageTransformer compositePageTransformer = new CompositePageTransformer();
compositePageTransformer.addTransformer(new ScaleInTransformer());
compositePageTransformer.addTransformer(new MarginPageTransformer((int) getResources().getDimension(R.dimen.dp10)));
viewPager2.setPageTransformer(compositePageTransformer);
//ViewPager2与Fragment 结合使用
viewPager2.setAdapter(new MyFragmentStateAdapter(this));
viewPager2.setOffscreenPageLimit(3);
}
}
FragmentFactory
package com.loaderman.viewpage2;
import androidx.fragment.app.Fragment;
import java.util.HashMap;
public class FragmentFactory {
private static HashMap<Integer, Fragment> savedFragment = new HashMap<Integer, Fragment>();
public static Fragment getFragment(int position) {
Fragment fragment = savedFragment.get(position);
if (fragment == null) {
switch (position) {
case 0:
fragment = new Home1Fragment();
break;
case 1:
fragment = new Home2Fragment();
break;
case 2:
fragment = new Home3Fragment();
break;
case 3:
fragment = new Home4Fragment();
break;
}
savedFragment.put(position, fragment);
}
return fragment;
}
}
package com.loaderman.viewpage2;
import android.graphics.Color;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.fragment.app.Fragment;
public class Home1Fragment extends Fragment {
@Nullable
@Override
public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
TextView tv = new TextView(getContext());
tv.setText("Home1Fragment");
tv.setBackgroundColor(Color.RED);
return tv;
}
}
效果：
学习参考：https://juejin.im/post/5df4aabe6fb9a0161104c8eb 【kotlin学习参考】
标签：java,androidx,position,ViewPager2,import,Android,public,view 来源： https://www.cnblogs.com/loaderman/p/12096016.html