ScrollView的简单应用

    ScrollView可实现控件在超出屏幕范围的情况下滚动显示。
    用法：在XML文件中将需滚动的控件包含在ScrollView中，当控件超出屏幕范围时可通过滚动查看

布局文件:

<LinearLayout 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" 
    android:orientation="vertical">

    <Button
        android:id="@+id/up"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="UP"
        />

     <Button
        android:id="@+id/down"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="DOWN"
        />

    <ScrollView 
        android:id="@+id/scroll"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:scrollbars="none"
        >
    <TextView
        android:id="@+id/content"
        android:textSize="15sp"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"/>
    </ScrollView>
</LinearLayout>

MainActivity:

package com.example.lowp;

import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.View.OnTouchListener;
import android.widget.Button;
import android.widget.ScrollView;
import android.widget.TextView;
import android.widget.Toast;


public class MainActivity extends Activity implements OnClickListener{

    private TextView textView;
    private ScrollView scrollView;
    private Button but_up;
    private Button but_down;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        but_up = (Button)findViewById(R.id.up);
        but_up.setOnClickListener(this);
        but_down = (Button)findViewById(R.id.down);
        but_down.setOnClickListener(this);

        textView = (TextView)findViewById(R.id.content);
        textView.setText(getResources().getString(R.string.content));

        scrollView = (ScrollView)findViewById(R.id.scroll);
        scrollView.setOnTouchListener(new OnTouchListener() {

            @Override
            public boolean onTouch(View v, MotionEvent event) {
                switch (event.getAction()) {

                case MotionEvent.ACTION_MOVE:
                    /**
                     * （1）getSrcollY()——滚动条滑动的距离
                     * 
                     */

                    //顶部状态
                    if(scrollView.getScrollY() <= 0){
                        Log.i("main", "顶部");
                    }                   
                    //底部状态
                    //TextView的总高度 <= 屏幕高度 + 滚动条的滑动距离
                    if(scrollView.getChildAt(0).getMeasuredHeight() <= scrollView.getHeight() + scrollView.getScrollY()){
                        Log.i("main", "底部");
                        Log.i("main", "TextView的总高度 = " + scrollView.getChildAt(0).getMeasuredHeight() + "   屏幕高度 = " + scrollView.getHeight() + "   滚动条的滑动距离 = " + scrollView.getScrollY()) ;
                        Toast.makeText(MainActivity.this, "底部", 1).show();

                        textView.append(getResources().getString(R.string.content));
                    }
                    break;
                }
                return false;
            }
        });

    }

    @Override
    public void onClick(View v) {
        switch (v.getId()) {
        /**
         * scrollTo:始终以滚动试图起点位置开始计算
         * scrollBy:以上一次滚动试图的位置开始计算
         */

        case R.id.up:
            scrollView.scrollBy(0, -30);
            break;
        case R.id.down:
            scrollView.scrollBy(0, 30);
            break;

        }

    }

}

运行效果: