本文實例講述了Android中ListView下拉刷新的實現方法。分享給大家供大家參考，具體如下：
ListView中的下拉刷新是非常常見的，也是經常使用的，看到有很多同學想要，那我就整理一下，供大家參考。那我就不解釋，直接上代碼了。
這里需要自己重寫一下ListView,重寫代碼如下:
package net.loonggg.listview; 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.LinearInterpolator; import android.view.animation.RotateAnimation; import android.widget.AbsListView; import android.widget.AbsListView.OnScrollListener; import android.widget.ImageView; import android.widget.LinearLayout; import android.widget.ListView; import android.widget.ProgressBar; import android.widget.TextView; public class MyListView extends ListView implements OnScrollListener { private final static int RELEASE_To_REFRESH = 0;// 下拉過程的狀態值 private final static int PULL_To_REFRESH = 1; // 從下拉返回到不刷新的狀態值 private final static int REFRESHING = 2;// 正在刷新的狀態值 private final static int DONE = 3; private final static int LOADING = 4; // 實際的padding的距離與界面上偏移距離的比例 private final static int RATIO = 3; private LayoutInflater inflater; // ListView頭部下拉刷新的布局 private LinearLayout headerView; private TextView lvHeaderTipsTv; private TextView lvHeaderLastUpdatedTv; private ImageView lvHeaderArrowIv; private ProgressBar lvHeaderProgressBar; // 定義頭部下拉刷新的布局的高度 private int headerContentHeight; private RotateAnimation animation; private RotateAnimation reverseAnimation; private int startY; private int state; private boolean isBack; // 用于保證startY的值在一個完整的touch事件中只被記錄一次 private boolean isRecored; private OnRefreshListener refreshListener; private boolean isRefreshable; public MyListView(Context context) { super(context); init(context); } public MyListView(Context context, AttributeSet attrs) { super(context, attrs); init(context); } private void init(Context context) { setCacheColorHint(context.getResources().getColor(R.color.transparent)); inflater = LayoutInflater.from(context); headerView = (LinearLayout) inflater.inflate(R.layout.lv_header, null); lvHeaderTipsTv = (TextView) headerView .findViewById(R.id.lvHeaderTipsTv); lvHeaderLastUpdatedTv = (TextView) headerView .findViewById(R.id.lvHeaderLastUpdatedTv); lvHeaderArrowIv = (ImageView) headerView .findViewById(R.id.lvHeaderArrowIv); // 設置下拉刷新圖標的最小高度和寬度 lvHeaderArrowIv.setMinimumWidth(70); lvHeaderArrowIv.setMinimumHeight(50); lvHeaderProgressBar = (ProgressBar) headerView .findViewById(R.id.lvHeaderProgressBar); measureView(headerView); headerContentHeight = headerView.getMeasuredHeight(); // 設置內邊距，正好距離頂部為一個負的整個布局的高度，正好把頭部隱藏 headerView.setPadding(0, -1 * headerContentHeight, 0, 0); // 重繪一下 headerView.invalidate(); // 將下拉刷新的布局加入ListView的頂部 addHeaderView(headerView, null, false); // 設置滾動監聽事件 setOnScrollListener(this); // 設置旋轉動畫事件 animation = new RotateAnimation(0, -180, RotateAnimation.RELATIVE_TO_SELF, 0.5f, RotateAnimation.RELATIVE_TO_SELF, 0.5f); animation.setInterpolator(new LinearInterpolator()); animation.setDuration(250); animation.setFillAfter(true); reverseAnimation = new RotateAnimation(-180, 0, RotateAnimation.RELATIVE_TO_SELF, 0.5f, RotateAnimation.RELATIVE_TO_SELF, 0.5f); reverseAnimation.setInterpolator(new LinearInterpolator()); reverseAnimation.setDuration(200); reverseAnimation.setFillAfter(true); // 一開始的狀態就是下拉刷新完的狀態，所以為DONE state = DONE; // 是否正在刷新 isRefreshable = false; } @Override public void onScrollStateChanged(AbsListView view, int scrollState) { } @Override public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) { if (firstVisibleItem == 0) { isRefreshable = true; } else { isRefreshable = false; } } @Override public boolean onTouchEvent(MotionEvent ev) { if (isRefreshable) { switch (ev.getAction()) { case MotionEvent.ACTION_DOWN: if (!isRecored) { isRecored = true; startY = (int) ev.getY();// 手指按下時記錄當前位置 } break; case MotionEvent.ACTION_UP: if (state != REFRESHING && state != LOADING) { if (state == PULL_To_REFRESH) { state = DONE; changeHeaderViewByState(); } if (state == RELEASE_To_REFRESH) { state = REFRESHING; changeHeaderViewByState(); onLvRefresh(); } } isRecored = false; isBack = false; break; case MotionEvent.ACTION_MOVE: int tempY = (int) ev.getY(); if (!isRecored) { isRecored = true; startY = tempY; } if (state != REFRESHING && isRecored && state != LOADING) { // 保證在設置padding的過程中，當前的位置一直是在head，否則如果當列表超出屏幕的話，當在上推的時候，列表會同時進行滾動 // 可以松手去刷新了 if (state == RELEASE_To_REFRESH) { setSelection(0); // 往上推了，推到了屏幕足夠掩蓋head的程度，但是還沒有推到全部掩蓋的地步 if (((tempY - startY) / RATIO < headerContentHeight)// 由松開刷新狀態轉變到下拉刷新狀態 && (tempY - startY) > 0) { state = PULL_To_REFRESH; changeHeaderViewByState(); } // 一下子推到頂了 else if (tempY - startY <= 0) {// 由松開刷新狀態轉變到done狀態 state = DONE; changeHeaderViewByState(); } } // 還沒有到達顯示松開刷新的時候,DONE或者是PULL_To_REFRESH狀態 if (state == PULL_To_REFRESH) { setSelection(0); // 下拉到可以進入RELEASE_TO_REFRESH的狀態 if ((tempY - startY) / RATIO >= headerContentHeight) {// 由done或者下拉刷新狀態轉變到松開刷新 state = RELEASE_To_REFRESH; isBack = true; changeHeaderViewByState(); } // 上推到頂了 else if (tempY - startY <= 0) {// 由DOne或者下拉刷新狀態轉變到done狀態 state = DONE; changeHeaderViewByState(); } } // done狀態下 if (state == DONE) { if (tempY - startY > 0) { state = PULL_To_REFRESH; changeHeaderViewByState(); } } // 更新headView的size if (state == PULL_To_REFRESH) { headerView.setPadding(0, -1 * headerContentHeight + (tempY - startY) / RATIO, 0, 0); } // 更新headView的paddingTop if (state == RELEASE_To_REFRESH) { headerView.setPadding(0, (tempY - startY) / RATIO - headerContentHeight, 0, 0); } } break; default: break; } } return super.onTouchEvent(ev); } // 當狀態改變時候，調用該方法，以更新界面 private void changeHeaderViewByState() { switch (state) { case RELEASE_To_REFRESH: lvHeaderArrowIv.setVisibility(View.VISIBLE); lvHeaderProgressBar.setVisibility(View.GONE); lvHeaderTipsTv.setVisibility(View.VISIBLE); lvHeaderLastUpdatedTv.setVisibility(View.VISIBLE); lvHeaderArrowIv.clearAnimation();// 清除動畫 lvHeaderArrowIv.startAnimation(animation);// 開始動畫效果 lvHeaderTipsTv.setText("松開刷新"); break; case PULL_To_REFRESH: lvHeaderProgressBar.setVisibility(View.GONE); lvHeaderTipsTv.setVisibility(View.VISIBLE); lvHeaderLastUpdatedTv.setVisibility(View.VISIBLE); lvHeaderArrowIv.clearAnimation(); lvHeaderArrowIv.setVisibility(View.VISIBLE); // 是由RELEASE_To_REFRESH狀態轉變來的 if (isBack) { isBack = false; lvHeaderArrowIv.clearAnimation(); lvHeaderArrowIv.startAnimation(reverseAnimation); lvHeaderTipsTv.setText("下拉刷新"); } else { lvHeaderTipsTv.setText("下拉刷新"); } break; case REFRESHING: headerView.setPadding(0, 0, 0, 0); lvHeaderProgressBar.setVisibility(View.VISIBLE); lvHeaderArrowIv.clearAnimation(); lvHeaderArrowIv.setVisibility(View.GONE); lvHeaderTipsTv.setText("正在刷新..."); lvHeaderLastUpdatedTv.setVisibility(View.VISIBLE); break; case DONE: headerView.setPadding(0, -1 * headerContentHeight, 0, 0); lvHeaderProgressBar.setVisibility(View.GONE); lvHeaderArrowIv.clearAnimation(); lvHeaderArrowIv.setImageResource(R.drawable.arrow); lvHeaderTipsTv.setText("下拉刷新"); lvHeaderLastUpdatedTv.setVisibility(View.VISIBLE); break; } } // 此方法直接照搬自網絡上的一個下拉刷新的demo，此處是“估計”headView的width以及height private void measureView(View child) { ViewGroup.LayoutParams params = child.getLayoutParams(); if (params == null) { params = new ViewGroup.LayoutParams( ViewGroup.LayoutParams.FILL_PARENT, ViewGroup.LayoutParams.WRAP_CONTENT); } int childWidthSpec = ViewGroup.getChildMeasureSpec(0, 0 + 0, params.width); int lpHeight = params.height; int childHeightSpec; if (lpHeight > 0) { childHeightSpec = MeasureSpec.makeMeasureSpec(lpHeight, MeasureSpec.EXACTLY); } else { childHeightSpec = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED); } child.measure(childWidthSpec, childHeightSpec); } public void setonRefreshListener(OnRefreshListener refreshListener) { this.refreshListener = refreshListener; isRefreshable = true; } public interface OnRefreshListener { public void onRefresh(); } public void onRefreshComplete() { state = DONE; lvHeaderLastUpdatedTv.setText("最近更新:" + new Date().toLocaleString()); changeHeaderViewByState(); } private void onLvRefresh() { if (refreshListener != null) { refreshListener.onRefresh(); } } public void setAdapter(LvAdapter adapter) { lvHeaderLastUpdatedTv.setText("最近更新:" + new Date().toLocaleString()); super.setAdapter(adapter); } }重寫完ListView之后，在布局文件中是這么使用的，頭部下拉刷新的布局文件lv_header.xml代碼如下：
<?xml version="1.0" encoding="utf-8"?> <!-- ListView的頭部 --> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="fill_parent" android:layout_height="wrap_content" android:background="#000000" > <!-- 內容 --> <RelativeLayout android:id="@+id/head_contentLayout" android:layout_width="fill_parent" android:layout_height="wrap_content" android:paddingLeft="30dp" > <!-- 箭頭圖像、進度條 --> <FrameLayout android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_alignParentLeft="true" android:layout_centerVertical="true" > <!-- 箭頭 --> <ImageView android:id="@+id/lvHeaderArrowIv" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_gravity="center" android:src="@drawable/arrow" /> <!-- 進度條 --> <ProgressBar android:id="@+id/lvHeaderProgressBar" style="?android:attr/progressBarStyleSmall" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_gravity="center" android:visibility="gone" /> </FrameLayout> <!-- 提示、最近更新 --> <LinearLayout android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_centerHorizontal="true" android:gravity="center_horizontal" android:orientation="vertical" > <!-- 提示 --> <TextView android:id="@+id/lvHeaderTipsTv" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="下拉刷新" android:textColor="@color/white" android:textSize="20sp" /> <!-- 最近更新 --> <TextView android:id="@+id/lvHeaderLastUpdatedTv" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="上次更新" android:textColor="@color/gold" android:textSize="10sp" /> </LinearLayout> </RelativeLayout> </LinearLayout>
在Main.xml中進行設置，代碼如下：
<?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="fill_parent" android:layout_height="fill_parent" android:background="#000000" android:orientation="vertical" > <net.loonggg.listview.MyListView android:id="@+id/lv" android:layout_width="fill_parent" android:layout_height="fill_parent" /> </LinearLayout>
然后就是在MainActivity中實現，代碼如下：
package net.loonggg.listview; import java.util.ArrayList; import java.util.List; import net.loonggg.listview.MyListView.OnRefreshListener; import android.app.Activity; import android.os.AsyncTask; import android.os.Bundle; import android.view.View; public class MainActivity extends Activity { private List<String> list; private MyListView lv; private LvAdapter adapter; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); lv = (MyListView) findViewById(R.id.lv); list = new ArrayList<String>(); list.add("loonggg"); list.add("我們都是開發者"); list.add("我們都是開發者"); list.add("我們都是開發者"); list.add("我們都是開發者"); list.add("我們都是開發者"); list.add("我們都是開發者"); list.add("我們都是開發者"); list.add("我們都是開發者"); list.add("我們都是開發者"); list.add("我們都是開發者"); list.add("我們都是開發者"); list.add("我們都是開發者"); list.add("我們都是開發者"); list.add("我們都是開發者"); list.add("我們都是開發者"); list.add("我們都是開發者"); adapter = new LvAdapter(list, this); lv.setAdapter(adapter); lv.setonRefreshListener(new OnRefreshListener() { @Override public void onRefresh() { new AsyncTask<Void, Void, Void>() { protected Void doInBackground(Void... params) { try { Thread.sleep(1000); } catch (Exception e) { e.printStackTrace(); } list.add("刷新后添加的內容"); return null; } @Override protected void onPostExecute(Void result) { adapter.notifyDataSetChanged(); lv.onRefreshComplete(); } }.execute(null, null, null); } }); }}這里還需要為ListView設置一下Adapter,自定義的Adapter如下：
package net.loonggg.listview; import java.util.List; import android.content.Context; import android.view.View; import android.view.ViewGroup; import android.widget.BaseAdapter; import android.widget.TextView; public class LvAdapter extends BaseAdapter { private List<String> list; private Context context; public LvAdapter(List<String> list, Context context) { this.list = list; this.context = context; } @Override public int getCount() { return list.size(); } @Override public Object getItem(int position) { return list.get(position); } @Override public long getItemId(int position) { return position; } @Override public View getView(int position, View convertView, ViewGroup parent) { TextView tv = new TextView(context.getApplicationContext()); tv.setText(list.get(position)); return tv; } }到這里就完了，代碼中的解釋非常詳細，具體的我就不多說了，也不解釋了，自己看看并研究吧！
希望本文所述對大家Android程序設計有所幫助。
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