1、使用ViewPager2实现懒加载 2、更新项目配置

Author: azhon

README.md

@@ -15,19 +15,20 @@
 ### 介绍：
 
 MVVM轻量快速开发框架：使用JetPack中的AndroidX + ViewModel + LiveData +
-DataBinding组件，同时使用RxJava2 + Retrofit2 + Glide等主流框架进行搭建
+DataBinding组件，同时使用ViewPager2 + RxJava2 + Retrofit2 +
+Glide等主流框架进行搭建
 
 <img src="https://img-blog.csdnimg.cn/2019040114344440.gif" width="300">
 
 ### Demo下载体验
 
-扫描下方二维码或者直接访问：[TODO-MVVM](https://www.pgyer.com/mvvm)
+点击下载：[TODO-MVVM](https://github.com/azhon/TODO-MVVM/releases/download/mvvm.apk)
 
-<img src="https://github.com/azhon/TODO-MVVM/blob/master/img/img_code.png" width="150" height="150">
 
 ### 项目编译
 
- 因为本项目使用的都是较新的东西，所以建议使用`Android Studio 3.5`或更高版本进行编译
+ 因为本项目使用的都是较新的东西，所以建议使用`Android Studio
+ 3.6.1`或更高版本进行编译
 
 ### 使用步骤
 

basicLib/build.gradle

@@ -37,11 +37,13 @@ dependencies {
     api 'com.squareup.retrofit2:adapter-rxjava2:2.4.0'
     api 'io.reactivex.rxjava2:rxjava:2.1.16'
     api 'io.reactivex.rxjava2:rxandroid:2.0.2'
-    api 'androidx.recyclerview:recyclerview:1.0.0'
+    api 'androidx.recyclerview:recyclerview:1.1.0'
     api 'com.github.bumptech.glide:glide:4.9.0'
     api 'com.android.support:design:28.0.0'
     api 'androidx.appcompat:appcompat:1.1.0'
     api 'androidx.constraintlayout:constraintlayout:1.1.3'
+    api 'androidx.viewpager2:viewpager2:1.0.0'
+    api 'com.google.android.material:material:1.1.0'
     annotationProcessor 'com.github.bumptech.glide:compiler:4.9.0'
     testImplementation 'junit:junit:4.12'
     androidTestImplementation 'androidx.test.ext:junit:1.1.1'

basicLib/src/main/java/com/azhon/basic/base/BaseLazyFragment.java

@@ -1,13 +1,7 @@
 package com.azhon.basic.base;
 
-import android.os.Bundle;
-import android.view.LayoutInflater;
-import android.view.View;
-import android.view.ViewGroup;
-
-import androidx.annotation.NonNull;
-import androidx.annotation.Nullable;
 import androidx.databinding.ViewDataBinding;
+import androidx.lifecycle.LifecycleObserver;
 
 import com.azhon.basic.lifecycle.BaseViewModel;
 
@@ -22,57 +16,15 @@
  */
 
 public abstract class BaseLazyFragment<VM extends BaseViewModel, DB extends ViewDataBinding>
-        extends BaseFragment<VM, DB> {
-
-    /**
-     * 懒加载
-     */
-    private boolean createView, activityCreated, lazy;
-    /**
-     * 这个Fragment是不是tab页面的第一个页面
-     */
-    private boolean isFirstTab;
+        extends BaseFragment<VM, DB> implements LifecycleObserver {
 
-    @Nullable
-    @Override
-    public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
-        View view = super.onCreateView(inflater, container, savedInstanceState);
-        createView = true;
-        return view;
-    }
-
-    @Override
-    public void onActivityCreated(@Nullable Bundle savedInstanceState) {
-        super.onActivityCreated(savedInstanceState);
-        activityCreated = true;
-    }
-
-    @Override
-    public void setUserVisibleHint(boolean isVisibleToUser) {
-        super.setUserVisibleHint(isVisibleToUser);
-        if (isVisibleToUser && createView && activityCreated && !lazy) {
-            //不是第一个Tab的Fragment 进行懒加载请求数据
-            lazy = true;
-            lazyLoad();
-        } else if (isVisibleToUser && !createView && !activityCreated && !lazy) {
-            //这个Fragment是多个Tab中的第一个
-            isFirstTab = true;
-        } else {
-            //对用户可见时，是否需要重新刷新数据
-            if (isVisibleToUser) {
-                visibleToUser();
-            }
-        }
-    }
+    private boolean visibleToUser;
 
     @Override
     public void onResume() {
         super.onResume();
-        /**
-         * 第一个Tab页面懒加载
-         */
-        if (isFirstTab && !lazy) {
-            lazy = true;
+        if (!visibleToUser) {
+            visibleToUser = true;
             lazyLoad();
         }
     }
@@ -81,9 +33,4 @@ public void onResume() {
      * 懒加载，只有在Fragment第一次创建且第一次对用户可见
      */
     protected abstract void lazyLoad();
-
-    /**
-     * 每次在Fragment与用户可见状态且不是第一次对用户可见
-     */
-    protected abstract void visibleToUser();
 }

build.gradle

@@ -7,7 +7,7 @@ buildscript {
 
     }
     dependencies {
-        classpath 'com.android.tools.build:gradle:3.6.0-alpha01'
+        classpath 'com.android.tools.build:gradle:3.6.1'
 
         // NOTE: Do not place your application dependencies here; they belong
         // in the individual module build.gradle files

gradle/wrapper/gradle-wrapper.properties

@@ -1,6 +1,6 @@
-#Wed Oct 30 13:16:57 CST 2019
+#Wed Mar 25 22:55:36 CST 2020
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-5.4.1-all.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-5.6.4-all.zip

img/img_1.png

@@ -1,14 +1,16 @@
 package com.azhon.mvvm.lazy;
 
-import androidx.annotation.Nullable;
+import androidx.annotation.NonNull;
 import androidx.fragment.app.Fragment;
-import androidx.fragment.app.FragmentPagerAdapter;
-import androidx.viewpager.widget.ViewPager;
+import androidx.fragment.app.FragmentActivity;
+import androidx.viewpager2.adapter.FragmentStateAdapter;
+import androidx.viewpager2.widget.ViewPager2;
 
 import com.azhon.basic.base.BaseNoModelActivity;
 import com.azhon.mvvm.R;
 import com.azhon.mvvm.databinding.ActivityLazyBinding;
 import com.google.android.material.tabs.TabLayout;
+import com.google.android.material.tabs.TabLayoutMediator;
 
 import java.util.ArrayList;
 import java.util.List;
@@ -36,7 +38,7 @@ protected int onCreate() {
     @Override
     protected void initView() {
         setTitle("Fragment懒加载使用示例");
-        ViewPager viewPager = dataBinding.viewPager;
+        ViewPager2 viewPager = dataBinding.viewPager;
         TabLayout tabLayout = dataBinding.tabLayout;
 
         list.add(LazyFragment.newInstance("5562b419e4b00c57d9b94ae2"));
@@ -51,10 +53,14 @@ protected void initView() {
         tabLayout.addTab(tabLayout.newTab().setText(title[2]), 2);
         tabLayout.addTab(tabLayout.newTab().setText(title[3]), 3);
 
-        MyFragmentPagerAdapter adapter = new MyFragmentPagerAdapter();
+        MyFragmentPagerAdapter adapter = new MyFragmentPagerAdapter(this);
         viewPager.setAdapter(adapter);
-        tabLayout.setupWithViewPager(viewPager);
-        tabLayout.setTabsFromPagerAdapter(adapter);
+        new TabLayoutMediator(tabLayout, viewPager, new TabLayoutMediator.TabConfigurationStrategy() {
+            @Override
+            public void onConfigureTab(@NonNull TabLayout.Tab tab, int position) {
+                tab.setText(title[position]);
+            }
+        }).attach();
 
     }
 
@@ -63,25 +69,21 @@ protected void initData() {
 
     }
 
-    private class MyFragmentPagerAdapter extends FragmentPagerAdapter {
-        public MyFragmentPagerAdapter() {
-            super(LazyActivity.this.getSupportFragmentManager());
+    public class MyFragmentPagerAdapter extends FragmentStateAdapter {
+
+        public MyFragmentPagerAdapter(@NonNull FragmentActivity fragmentActivity) {
+            super(fragmentActivity);
         }
 
         @Override
-        public Fragment getItem(int position) {
+        public Fragment createFragment(int position) {
             return list.get(position);
         }
 
         @Override
-        public int getCount() {
+        public int getItemCount() {
             return list.size();
         }
-
-        @Nullable
-        @Override
-        public CharSequence getPageTitle(int position) {
-            return title[position];
-        }
     }
+
 }

img/img_code.png

@@ -80,11 +80,6 @@ protected void lazyLoad() {
         viewModel.loadData(category);
     }
 
-    @Override
-    protected void visibleToUser() {
-        Log.e(TAG, "与用户可见 " + category);
-    }
-
     @Override
     public void onItemClick(JueJinBean.DBean.EntrylistBean bean, int position) {
         startActivity(new Intent(context, DetailActivity.class)

sample/src/main/java/com/azhon/mvvm/lazy/LazyActivity.java

@@ -26,7 +26,7 @@
             android:layout_height="1dp"
             android:background="#eeeeee" />
 
-        <androidx.viewpager.widget.ViewPager
+        <androidx.viewpager2.widget.ViewPager2
             android:id="@+id/view_pager"
             android:layout_width="match_parent"
             android:layout_height="0dp"

sample/src/main/java/com/azhon/mvvm/lazy/LazyFragment.java

@@ -1,5 +1,5 @@
 <resources>
     <string name="app_name">TODO-MVVM</string>
-    <string name="introduce">　MVVM轻量快速开发框架：使用JetPack中的AndroidX + ViewModel + LiveData + DataBinding组件，同时使用RxJava2 + Retrofit2 + Glide等主流框架进行搭建</string>
+    <string name="introduce">　MVVM轻量快速开发框架：使用JetPack中的AndroidX + ViewModel + LiveData + DataBinding组件，同时使用ViewPager2 + RxJava2 + Retrofit2 + Glide等主流框架进行搭建</string>
     <string name="vm_hint">　在当前页面开启屏幕自动旋转，旋转为横屏页面会重新创建；但是之前请求的数据依旧还在，这也许就是ViewModel的魅力所在。（manifest中没有配置android:configChanges）</string>
 </resources>