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炫酷-背景图上下循环滚动登录页，Android RecyclerView实现方法
某站的登录页背景不停循环滚动，和街边的广告箱很像，感觉不错我也心动了。决定高仿一下，参考了几篇文章后就动手了。
实现步骤：
1.效果图展示
2.自定义实现滚动效果RecyclerView
3.适配器Adapter实现
4.适配器布局文件
5.主程序调用过程
6.主布局文件
7.总结
1.效果图展示
image
2.自定义实现滚动效果RecyclerView
AutoPollRecyclerView.java
public class AutoPollRecyclerView extends RecyclerView {
private static final long TIME_AUTO_POLL = 16;
AutoPollTask autoPollTask;
private boolean running; //标示是否正在自动轮询
private boolean canRun;//标示是否可以自动轮询,可在不需要的是否置false
public AutoPollRecyclerView(Context context, @Nullable AttributeSet attrs) {
super(context, attrs);
autoPollTask = new AutoPollTask(this);
}
static class AutoPollTask implements Runnable {
private final WeakReference<AutoPollRecyclerView> mReference;
//使用弱引用持有外部类引用->防止内存泄漏
public AutoPollTask(AutoPollRecyclerView reference) {
this.mReference = new WeakReference<AutoPollRecyclerView>(reference);
}
@Override
public void run() {
AutoPollRecyclerView recyclerView = mReference.get();
if (recyclerView != null && recyclerView.running && recyclerView.canRun) {
recyclerView.scrollBy(2, 2);
recyclerView.postDelayed(recyclerView.autoPollTask, recyclerView.TIME_AUTO_POLL);
}
}
}
//开启:如果正在运行,先停止->再开启
public void start() {
if (running)
stop();
canRun = true;
running = true;
postDelayed(autoPollTask, TIME_AUTO_POLL);
}
public void stop() {
running = false;
removeCallbacks(autoPollTask);
}
@Override
public boolean onTouchEvent(MotionEvent e) {
switch (e.getAction()) {
case MotionEvent.ACTION_DOWN:
if (running)
stop();
break;
case MotionEvent.ACTION_UP:
case MotionEvent.ACTION_CANCEL:
case MotionEvent.ACTION_OUTSIDE:
if (canRun)
start();
break;
}
//return false，注释掉onTouchEvent()方法里面的stop和start方法，则列表自动滚动且不可触摸
return super.onTouchEvent(e);}
}
3.适配器Adapter实现
AutoPollAdapter.java
public class AutoPollAdapter extends RecyclerView.Adapter<AutoPollAdapter.BaseViewHolder> {
private final Context mContext;
public AutoPollAdapter(Context context) {
this.mContext = context;
}
@Override
public BaseViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View view = LayoutInflater.from(mContext).inflate(R.layout.auto_list_item, parent, false);
BaseViewHolder holder = new BaseViewHolder(view);
return holder;
}
@Override
public void onBindViewHolder(BaseViewHolder holder, int position) {
}
@Override
public int getItemCount() {
return Integer.MAX_VALUE;
}
class BaseViewHolder extends RecyclerView.ViewHolder {
ImageView imageView;
public BaseViewHolder(View itemView) {
super(itemView);
imageView = itemView.findViewById(R.id.iv_login_bg);
}
}
}
4.适配器布局文件
auto_list_item.xml
<?xml version="1.0" encoding="utf-8"?>
<ImageView xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/iv_login_bg"
android:layout_width="480dp"
android:layout_height="2065dp"
android:scaleType="matrix"
android:adjustViewBounds="true"
android:background="@drawable/login_bg01"/>
5.主程序调用过程
LoginActivity.java
public class LoginActivity extends AppCompatActivity {
private AutoPollRecyclerView recyclerView;
@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_login);
recyclerView = findViewById(R.id.recyclerview);
recyclerView.setLayoutManager(
new LinearLayoutManager(
this,
//设置LinearLayoutManager.HORIZONTAL 则水平滚动
LinearLayoutManager.VERTICAL, false));
AutoPollAdapter autoPollAdapter = new AutoPollAdapter(getApplicationContext());
recyclerView.setAdapter(autoPollAdapter);
//启动滚动
recyclerView.start();
}
}
6.主布局文件
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent">
<com.imooc.guessmusic.view.AutoPollRecyclerView
android:id="@+id/recyclerview"
android:layout_width="match_parent"
android:layout_height="wrap_content"
tools:ignore="MissingConstraints" />
<ImageView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:scaleType="fitXY"
android:src="@drawable/login_dark" />
<ImageView
android:layout_width="120dp"
android:layout_height="120dp"
android:layout_gravity="center_horizontal"
android:layout_marginTop="120dp"
android:src="@drawable/login_logo" />
<TextView
android:layout_width="400dp"
android:layout_height="60dp"
android:layout_marginTop="60dp"
android:layout_gravity="center"
android:background="@drawable/btn_c"
android:gravity="center"
android:textSize="22sp"
android:textStyle="bold"
android:textColor="@color/black"
android:text="微信登录" />
<TextView
android:layout_width="400dp"
android:layout_height="60dp"
android:layout_marginTop="150dp"
android:layout_gravity="center"
android:background="@drawable/btn_c_b"
android:gravity="center"
android:textSize="22sp"
android:textColor="@color/text_white"
android:text="手机号码快捷登录" />
</FrameLayout>
7.总结
Demo里面使用了沉浸式效果，如何实现请参考下面的文章。
Android-沉浸式的实现
Demo里面使用了今日头条适配方案能适配97%的手机，3%刘海屏与水滴屏未做适配，是如何实现请参考下面的文章。
今日头条的屏幕适配方案，简易使用
核心代码就是自定义的RecyclerView代码，如果你想做其它效果的滚动可以参考下面的文章。
Android实现类似中奖信息自动滚动效果
原代码献上：https://pan.baidu.com/s/18sy-Gvjav8Dz2PwctrDcFw
提取码：sr0i
作者：Perston
链接：https://www.jianshu.com/p/8e3bd35c8a82
