重写ListView实现下拉刷新上拉加载
Android本身的ListView没有刷新功能,要想实现这一功能,就得继承ListView并重写它的方法。同时也要实现其OnScrollListener这一接口。
下拉刷新,需要在原本的ListView上部添加一个Head,ListView本身提供了addHeadView()这一方法,但是没有实现刷新的功能,我们可以自定义Head的内容,并加上刷新的功能。
上拉加载更多数据与下拉刷新类似,是在ListView的下部添加一个Footer。具体实现代码如下:
import java.text.SimpleDateFormat; import java.util.Date; import android.content.Context; import android.util.AttributeSet; import android.view.LayoutInflater; import android.view.MotionEvent; import android.view.View; import android.view.ViewGroup; import android.view.animation.RotateAnimation; import android.widget.AbsListView; import android.widget.ImageView; import android.widget.ListView; import android.widget.AbsListView.OnScrollListener; import android.widget.ProgressBar; import android.widget.TextView; public class ReFlashListView extends ListView implements OnScrollListener { View header; View footer; int headerHeight; int firstVisibleItem; // 当前第一个可见Item的位置 boolean isRemark; // 标记第一个出现的Item int startY; // 按下时的Y值 int state; // 当前的状态 int scrollState; // 滚动状态 final int NONE = 0; // 正常状态 final int PULL = 1; // 下拉刷新状态 final int RELESE = 2; // 松开释放状态 final int REFLASHING = 3; // 正在刷新状态 IReflashListener iReflashListener; int totalItemCount; int lastVisibleItem; boolean isLoading; //正在加载 private TextView txtViewLoading = null; private ProgressBar prgBarLoading = null; public ReFlashListView(Context context) { super(context); initView(context); // TODO Auto-generated constructor stub } public ReFlashListView(Context context, AttributeSet attrs) { super(context, attrs); initView(context); // TODO Auto-generated constructor stub } public ReFlashListView(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); initView(context); // TODO Auto-generated constructor stub } // 初始化界面,添加顶部布局至ListView public void initView(Context context) { LayoutInflater inflater = LayoutInflater.from(context); header = inflater.inflate(R.layout.header_layout, null); footer=inflater.inflate(R.layout.footer_layout, null); footer.findViewById(R.id.load_layout).setVisibility(View.GONE); measureView(header); headerHeight = header.getMeasuredHeight(); topPadding(-headerHeight); this.addHeaderView(header); this.addFooterView(footer); this.setOnScrollListener(this); txtViewLoading = (TextView)footer.findViewById(R.id.text_loading); prgBarLoading = (ProgressBar)footer.findViewById(R.id.loading_progress); } // 设置header布局的上边距 private void topPadding(int topPadding) { header.setPadding(header.getPaddingLeft(), topPadding, header.getPaddingRight(), header.getPaddingBottom()); header.invalidate(); } // 通知父布局占用的宽,高 private void measureView(View view) { ViewGroup.LayoutParams p = view.getLayoutParams(); if (p == null) { p = new ViewGroup.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.WRAP_CONTENT); } int width = ViewGroup.getChildMeasureSpec(0, 0, p.width); int height; int tempHeight = p.height; if (tempHeight > 0) { height = MeasureSpec.makeMeasureSpec(tempHeight, MeasureSpec.EXACTLY); } else { height = MeasureSpec.makeMeasureSpec(tempHeight, MeasureSpec.UNSPECIFIED); } view.measure(width, height); } @Override public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) { this.firstVisibleItem = firstVisibleItem; this.totalItemCount=totalItemCount; this.lastVisibleItem=firstVisibleItem+visibleItemCount; } @Override public void onScrollStateChanged(AbsListView view, int scrollState) { this.scrollState = scrollState; if(totalItemCount==lastVisibleItem && scrollState == SCROLL_STATE_IDLE){ if(!isLoading){ isLoading=true; footer.findViewById(R.id.load_layout).setVisibility(View.VISIBLE); iReflashListener.onLoad(); } } } @Override public boolean onTouchEvent(MotionEvent ev) { switch (ev.getAction()) { case MotionEvent.ACTION_DOWN: if (firstVisibleItem == 0) { isRemark = true; startY = (int) ev.getY(); } break; case MotionEvent.ACTION_MOVE: onMove(ev); break; case MotionEvent.ACTION_UP: if (state == RELESE) { state = REFLASHING; //刷新数据 iReflashListener.onReflash(); reflashViewByState(); } else if (state == PULL) { state = NONE; isRemark = false; reflashViewByState(); } break; } return super.onTouchEvent(ev); } /* * 判断移动过程中的操作 */ private void onMove(MotionEvent e) { int tempY = (int) e.getY(); int space = tempY - startY; int topPadding = space - headerHeight; if (!isRemark) { return; } switch (state) { case NONE: if (space > 0) { state = PULL; reflashViewByState(); } break; case PULL: topPadding(topPadding); if (space > headerHeight + 30 && scrollState == SCROLL_STATE_TOUCH_SCROLL) { state = RELESE; reflashViewByState(); } break; case RELESE: topPadding(topPadding); if (space < headerHeight + 30) { state = PULL; reflashViewByState(); } else if (space <= 0) { state = NONE; isRemark = false; reflashViewByState(); } break; } } /* * 根据当前状态,改变界面显示 */ private void reflashViewByState() { TextView tip = (TextView) header.findViewById(R.id.tip); ImageView arrow = (ImageView) header.findViewById(R.id.arrow); ProgressBar progress = (ProgressBar) header.findViewById(R.id.progress); RotateAnimation anim = new RotateAnimation(0, 180, RotateAnimation.RELATIVE_TO_SELF, 0.5f, RotateAnimation.RELATIVE_TO_SELF, 0.5f); anim.setDuration(500); anim.setFillAfter(true); RotateAnimation anim1 = new RotateAnimation(180, 0, RotateAnimation.RELATIVE_TO_SELF, 0.5f, RotateAnimation.RELATIVE_TO_SELF, 0.5f); anim1.setDuration(500); anim1.setFillAfter(true); switch (state) { case NONE: topPadding(-headerHeight); arrow.clearAnimation(); break; case PULL: arrow.setVisibility(View.VISIBLE); progress.setVisibility(View.GONE); tip.setText("下拉可以刷新"); arrow.clearAnimation(); arrow.setAnimation(anim1); break; case RELESE: arrow.setVisibility(View.VISIBLE); progress.setVisibility(View.GONE); tip.setText("松开可以刷新"); arrow.clearAnimation(); arrow.setAnimation(anim); break; case REFLASHING: topPadding(50); arrow.setVisibility(View.GONE); progress.setVisibility(View.VISIBLE); arrow.clearAnimation(); tip.setText("正在刷新..."); break; } } public void reflashComplete(){ state=NONE; reflashViewByState(); isRemark=false; TextView lastupdatetime=(TextView)header.findViewById(R.id.last_update_time); SimpleDateFormat format=new SimpleDateFormat("yyyy年MM月dd日 hh:mm:ss"); Date date=new Date(System.currentTimeMillis()); String time=format.format(date); lastupdatetime.setText(time); } public void loadingComplete(){ isLoading=false; footer.findViewById(R.id.load_layout).setVisibility(View.GONE); } public void allDataLoadingComplete(){ isLoading=false; txtViewLoading.setText("全部数据已经加载完成"); prgBarLoading.setVisibility(View.GONE); } public void setInterfacs(IReflashListener iReflashListener){ this.iReflashListener=iReflashListener; } public interface IReflashListener{ public void onReflash(); public void onLoad(); } }
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