分享一个可下拉刷新的ScrollView

原理：就是动态改变ScrollView header的margin实现

主要的代码：

http://blog.csdn.net/swust_chenpeng/article/details/39289721

代码其实还是比较容易，但是但是，自己还是花了很多时间，脑袋瓜不够灵活呀...

下面是ScrollViewHeader的代码：

public class ScrollViewHeader extends RelativeLayout {  

    public final static int STATE_NORMAL = 0;
    public final static int STATE_READY = 1;
    public final static int STATE_REFRESHING = 2;
    private final int ROTATE_ANIM_DURATION = 180;
    private int topMargin = 0;
    private int state = STATE_NORMAL;
    private TextView refreshTv = null;
    private TextView refreshTimeTv = null;
    private ProgressBar refreshProgress = null;
    private ImageView refreshArrow = null;
    private Animation animationUp = null;
    private Animation animationDown = null;  

    public ScrollViewHeader(Context context) {
        super(context);
        // TODO Auto-generated constructor stub
        if(!isInEditMode())
            initView(context);
    }  

    public ScrollViewHeader(Context context, AttributeSet attrs) {
        super(context, attrs);
        // TODO Auto-generated constructor stub
        if(!isInEditMode())
            initView(context);
    }  

    public ScrollViewHeader(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        // TODO Auto-generated constructor stub
        if(!isInEditMode())
            initView(context);
    }  

    /**
     * 初始化相关的view
     */
    public void initView(Context context) {
        animationDown = new RotateAnimation(-180f, 0, Animation.RELATIVE_TO_SELF, 0.5f, Animation.RELATIVE_TO_SELF, 0.5f);
        animationDown.setDuration(ROTATE_ANIM_DURATION);
        animationDown.setFillAfter(true);
        animationUp = new RotateAnimation(0, -180f, Animation.RELATIVE_TO_SELF, 0.5f, Animation.RELATIVE_TO_SELF, 0.5f);
        animationUp.setDuration(ROTATE_ANIM_DURATION);
        animationUp.setFillAfter(true);
        setPadding(10, 25, 10, 25);
        View view = LayoutInflater.from(context).inflate(R.layout.scrollview_header, this, true);
        refreshTv = (TextView) view.findViewById(R.id.refresh_text);
        refreshTimeTv = (TextView) view.findViewById(R.id.refresh_time);
        refreshProgress = (ProgressBar) view.findViewById(R.id.refresh_progress);
        refreshArrow = (ImageView) view.findViewById(R.id.refresh_arrow);
    }  

    /**
     * 设置scrollviewHeader的状态
     * @param state
     */
    public void setState(int state) {
        if(this.state == state) {
            return ;
        }
        switch (state) {
        case STATE_NORMAL:
            refreshTv.setText("下拉刷新");
            refreshArrow.setVisibility(View.VISIBLE);
            refreshProgress.setVisibility(View.INVISIBLE);
            if(this.state == STATE_READY) {
                refreshArrow.startAnimation(animationDown);
            } else if(this.state == STATE_REFRESHING) {
                refreshArrow.clearAnimation();
            }
            break;
        case STATE_READY:
            refreshTv.setText("松开刷新");
            refreshArrow.setVisibility(View.VISIBLE);
            refreshProgress.setVisibility(View.INVISIBLE);
            refreshArrow.startAnimation(animationUp);
            break;
        case STATE_REFRESHING:
            refreshTv.setText("正在加载...");
            refreshProgress.setVisibility(View.VISIBLE);
            refreshArrow.clearAnimation();
            refreshArrow.setVisibility(View.INVISIBLE);
            break;
        default:
            break;
        }
        this.state = state;
    }  

    /**
     * 更新header的margin
     * @param margin
     */
    public void updateMargin(int margin) {
        //这里用Linearlayout的原因是Headerview的父控件是scrollcontainer是一个linearlayout
        LinearLayout.LayoutParams params = (LinearLayout.LayoutParams) this.getLayoutParams();
        params.topMargin = margin;
        topMargin = margin;
        setLayoutParams(params);
    }  

    /**
     * 获取header的margin
     * @return
     */
    public int getTopMargin() {
        return topMargin;
    }
}  

header的布局文件，scrollview_header

<?xml version="1.0" encoding="utf-8"?>
<merge xmlns:android="http://schemas.android.com/apk/res/android" >  

    <LinearLayout
        android:id="@+id/refresh_des"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerInParent="true"
        android:gravity="center"
        android:orientation="vertical" >  

        <TextView
            android:id="@+id/refresh_text"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="下拉刷新" />  

        <TextView
            android:id="@+id/refresh_time"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="5分钟前更新" />
    </LinearLayout>  

    <ProgressBar
        android:id="@+id/refresh_progress"
        android:layout_width="30dip"
        android:layout_height="30dip"
        android:layout_centerVertical="true"
        android:layout_marginRight="10dip"
        android:layout_toLeftOf="@id/refresh_des"
        android:visibility="invisible" />  

    <ImageView
        android:id="@+id/refresh_arrow"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerVertical="true"
        android:layout_marginRight="10dip"
        android:layout_toLeftOf="@id/refresh_des"
        android:src="@drawable/arrow" />  

</merge>  

好了，相关的源码就只有3个文件...