首先是布局资源
activity_main.xml
<?xml version="1.0" encoding="utf-8"?><RelativeLayout 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" android:orientation="vertical" tools:context=".MainActivity"> <com.example.stickview.MyScrollView android:id="@+id/scroll" android:layout_width="match_parent" android:layout_height="wrap_content"> <LinearLayout android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical"> <TextView android:layout_width="match_parent" android:layout_height="200dp" android:background="#ffff00" /> <TextView android:id="@+id/t2" android:layout_width="match_parent" android:layout_height="100dp" android:background="@color/colorAccent" android:text="我是全局悬浮view"/> <TextView android:layout_width="match_parent" android:layout_height="600dp" android:background="@color/colorPrimaryDark" /> </LinearLayout> </com.example.stickview.MyScrollView> <TextView android:id="@+id/t1" android:layout_width="match_parent" android:layout_height="100dp" android:background="@color/colorAccent" android:text="我是假全局悬浮view" android:visibility="gone" /></RelativeLayout>MainActivity代码
package com.example.stickview;import androidx.appcompat.app.AppCompatActivity;import android.os.Bundle;import android.widget.TextView;public class MainActivity extends AppCompatActivity { MyScrollView scroll; TextView t1,t2; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); scroll = (MyScrollView)findViewById(R.id.scroll); t1 = (TextView)findViewById(R.id.t1); t2 = (TextView)findViewById(R.id.t2); scroll.setView(t1,t2); }}
自定义ScrollView代码
package com.example.stickview;import android.content.Context;import android.util.AttributeSet;import android.view.View;import android.widget.ScrollView;import android.widget.TextView;public class MyScrollView extends ScrollView { private static StopCall stopCall; Context ctx; TextView t1,t2; //ScrollView向上滑动到顶部的距离 private int upH; public MyScrollView(Context context) { super(context); } public MyScrollView(Context context, AttributeSet attrs) { super(context, attrs); this.ctx = context; //赋值：300很重要，这个值是顶部2上面的高度，也就是本例中图片的高度 upH = dpToPx(ctx,200);//单位是dp } public MyScrollView(Context context, AttributeSet attrs, int defStyleAttr) { super(context, attrs, defStyleAttr); } public static void setCallback(StopCall c){ stopCall =c ; } @Override protected void onScrollChanged(int l, int t, int oldl, int oldt) { super.onScrollChanged(l, t, oldl, oldt); if(t>upH) { stopSlide(true); } else{ stopSlide(false); } }/** * 接口实现，可不可就 */ public void stopSlide(boolean isStop){ if (isStop) { t1.setVisibility(View.VISIBLE); t2.setVisibility(View.GONE); } else { t2.setVisibility(View.VISIBLE); t1.setVisibility(View.GONE); } } public interface StopCall { public void stopSlide(boolean isStop); } public static int dpToPx(Context context,float dpValue) {//dp转换为px float scale=context.getResources().getDisplayMetrics().density;//获得当前屏幕密度 return (int)(dpValue*scale+0.5f); } public void setView(TextView t1,TextView t2) { this.t1 = t1; this.t2 = t2; } }