十、ScrollView简短应用

一、绘制界面，两个按钮，一个scrollview中添加一个textview

scrollview.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    xmlns:app="http://schemas.android.com/apk/res-auto">

    <Button
        android:id="@+id/scrollview_up"
        android:text="up"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />
    <Button
        android:id="@+id/scrollview_down"
        app:layout_constraintLeft_toRightOf="@+id/scrollview_up"
        android:text="down"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />
    <ScrollView
        android:id="@+id/scrollView_scrollview"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:scrollbars="none">

        <TextView
            android:id="@+id/scrollview_content"
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:textSize="20dp"/>
    </ScrollView>
</android.support.constraint.ConstraintLayout>

scrollview.java

package com.example.administrator.listview;

import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.MotionEvent;
import android.view.View;
import android.widget.Button;
import android.widget.ScrollView;
import android.widget.TextView;
import android.widget.Toast;

/**
 * Created by Administrator on 2018/3/16 0016.
 */

public class scrollview extends AppCompatActivity implements View.OnClickListener{
    private TextView scrollview_textview;
    private ScrollView scrollView;
    private Button scrollview_up;
    private Button scrollview_down;
    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.scrollview);
        scrollview_textview=findViewById(R.id.scrollview_content);
        scrollView=findViewById(R.id.scrollView_scrollview);
        scrollview_textview.setText(R.string.scrollviewcontent);
        scrollview_up=findViewById(R.id.scrollview_up);
        scrollview_down=findViewById(R.id.scrollview_down);
        scrollview_up.setOnClickListener(this);
        scrollview_down.setOnClickListener(this);
        scrollView.setOnTouchListener(new View.OnTouchListener() {
            @Override
            public boolean onTouch(View view, MotionEvent motionEvent) {
                switch (motionEvent.getAction()){
                    //手指何时抬起
                    case MotionEvent.ACTION_UP:{
                        Toast.makeText(scrollview.this,"手指何时抬起",Toast.LENGTH_SHORT).show();
                        System.out.println("手指何时抬起");
                        break;
                    }
                    //手指何时落下
                    case MotionEvent.ACTION_DOWN:{
                        System.out.println("手指何时落下");
                        break;
                    }
                    case MotionEvent.ACTION_MOVE:{
                        /*
                        * getscrollY()--滚动条滑动的距离
                        * getMeasuredHeight
                        * getHeight
                        * */
                        //顶部状态
                        if(scrollView.getScrollY()<=0){
                            System.out.println("onTouch: 滑动到顶部");
                        }
                        //底部状态
                        //当textview的高度<=屏幕的高度+滚动条的滚动距离
                        if (scrollView.getChildAt(0).getMeasuredHeight()
                                <=scrollView.getHeight()+scrollView.getScrollY()){
                            System.out.println("onTouch: 滑动到底部");
                            System.out.println("scrollView.getChildAt(0).getMeasuredHeight()"+scrollView.getChildAt(0).getMeasuredHeight()+" scrollView.getHeight()="+scrollView.getHeight()+" scrollView.getScrollY()"+scrollView.getScrollY());
                            //滑动到底部时，模拟刷新功能，向textview中添加一段文字
                            scrollview_textview.append(getResources().getString(R.string.scrollviewcontent));
                        }

                        break;
                    }
                }
                return false;
            }
        });
    }

    @Override
    public void onClick(View view) {
        /*
        * scrollTo一步到位
        * scrollBy可以持续点击
        * */
        switch (view.getId()){
            case R.id.scrollview_up:{
                scrollView.scrollBy(0,-30);
                break;
            }
            case R.id.scrollview_down:{
                scrollView.scrollBy(0,30);
                break;
            }
        }

    }
}