Android--GirdView下拉刷新功能

網上很少有關於GridView的下拉刷新數據，搜了一些解決方案，很多方法看起來很複雜，自己也沒有看懂（本人屬於頭腦笨的那種），不過這段文字給了我點啓發“具有下拉刷新功能的ListView/gridview其實也沒什麼複雜的，就是加一個head，然後判斷當前gridview時候拖動到了頂端，然後根據像下拖曳的距離與head的高度做對比以設置head的狀態（下拉刷新、鬆開刷新、還是隱藏掉等）”。其實GridView實現下拉刷新類似ListView是比較困難的，最主要的原因是gridView沒有addHeaderView方法，這也是爲什麼網上很少有關於GirdView的相關代碼，自己無意中按照上面那段話的啓示，把上一篇PullToRefreshListView類以及Activity裏面的佈局略加修改，在手機一運行居然實現了，把我樂的要命，給大家展示一下，代碼和ListView實現類似，代碼紅色部分爲不同處，大家看一下就知道比較簡單了（想想，很多事情都是相通的）。

//PullToRefreshGridView類複寫GridView，與ListView的PullToRefreshListView沒有多少區別，最主要的原因是gridView沒有addHeaderView方法，所以只能在GridView之前加head佈局,其他與ListView都是一樣的

packagesrc.com.lyg.refreshlist;

importjava.text.SimpleDateFormat;

importjava.util.Date;

importsrc.com.lyg.R;

importandroid.content.Context;

importandroid.util.AttributeSet;

importandroid.util.Log;

importandroid.view.LayoutInflater;

importandroid.view.MotionEvent;

importandroid.view.View;

importandroid.view.ViewGroup;

importandroid.view.animation.LinearInterpolator;

importandroid.view.animation.RotateAnimation;

importandroid.widget.AbsListView;

importandroid.widget.AbsListView.OnScrollListener;

importandroid.widget.BaseAdapter;

importandroid.widget.GridView;

importandroid.widget.ImageView;

importandroid.widget.LinearLayout;

importandroid.widget.ProgressBar;

importandroid.widget.TextView;

public classPullToRefreshGridView extends GridView implementsOnScrollListener {

private static final String TAG ="listview";

private final static intRELEASE_To_REFRESH = 0; // 釋放

private final static intPULL_To_REFRESH = 1;// 下拉刷新

private final static intREFRESHING = 2; // 正在刷新

private final static int DONE =3; // 按下

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;

private LinearLayout headView;

private TextView tipsTextview;

private TextView lastUpdatedTextView;

private ImageView arrowImageView;

private ProgressBar progressBar;

private RotateAnimation animation;

private RotateAnimation reverseAnimation;

// 用於保證startY的值在一個完整的touch事件中只被記錄一次

private boolean isRecored;

private int headContentWidth;

private int headContentHeight;

private int startY;

private int firstItemIndex;

private int state;

private boolean isBack;

private OnRefreshListener refreshListener;

private boolean isRefreshable;

public PullToRefreshGridViewActivity context;

publicPullToRefreshGridView(Context context){

super(context);

this.context=(PullToRefreshGridViewActivity)context;

init(context);

}

public PullToRefreshGridView(Context context, AttributeSetattrs) {

super(context, attrs);

this.context=(PullToRefreshGridViewActivity)context;

init(context);

}

public View getView(){

return headView;

}

private void init(Context context){

//setCacheColorHint(context.getResources().getColor(R.color.transparent));

inflater = LayoutInflater.from(context);

// head 佈局文件

headView = (LinearLayout) inflater.inflate(R.layout.head,null);

// 下拉箭頭

arrowImageView = (ImageView) headView.findViewById(R.id.head_arrowImageView);

arrowImageView.setMinimumWidth(70);

arrowImageView.setMinimumHeight(50);

// 進度條

progressBar = (ProgressBar) headView.findViewById(R.id.head_progressBar);

// 下拉提示刷新

tipsTextview = (TextView)headView.findViewById(R.id.head_tipsTextView);

//最新一次刷新時間

lastUpdatedTextView = (TextView)headView.findViewById(R.id.head_lastUpdatedTextView);

//計算head的高寬

measureView(headView);

headContentHeight = headView.getMeasuredHeight();

headContentWidth = headView.getMeasuredWidth();

//初始狀態是隱藏掉head 佈局

headView.setPadding(0, -1 * headContentHeight, 0, 0);

headView.invalidate();

Log.v("size", "width:" + headContentWidth + " height:" +headContentHeight);

setOnScrollListener(this);

//下拉以及恢復動畫

animation = new RotateAnimation(0, -180,RotateAnimation.RELATIVE_TO_SELF,0.5f,RotateAnimation.RELATIVE_TO_SELF,0.5f);

animation.setInterpolator(newLinearInterpolator());

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(newLinearInterpolator());

reverseAnimation.setDuration(200);

reverseAnimation.setFillAfter(true);

state = DONE;

isRefreshable = false;

}

public void onScroll(AbsListView arg0, intfirstVisiableItem, int arg2, int arg3){

firstItemIndex = firstVisiableItem;

}

public void onScrollStateChanged(AbsListView arg0,int arg1) {

}

public boolean onTouchEvent(MotionEvent event){

if (isRefreshable) {

switch (event.getAction()) {

// 在down時候記錄當前Y的位置

case MotionEvent.ACTION_DOWN:

if (firstItemIndex == 0 &&!isRecored) {

isRecored = true;

startY = (int) event.getY();

Log.v(TAG, "在down時候記錄當前位置‘");

}

break;

case MotionEvent.ACTION_UP:

if (state != REFRESHING&& state != LOADING){

if (state == DONE) {

// 什麼都不做

}

//由下拉刷新狀態，到done狀態

if (state == PULL_To_REFRESH) {

state = DONE;

changeHeaderViewByState();

Log.v(TAG, "由下拉刷新狀態，到done狀態");

}

if (state == RELEASE_To_REFRESH) {

state = REFRESHING;

changeHeaderViewByState();

onRefresh();

Log.v(TAG, "由鬆開刷新狀態，到done狀態");

}

isRecored = false;

isBack = false;

break;

case MotionEvent.ACTION_MOVE:

int tempY = (int) event.getY();

if (!isRecored &&firstItemIndex == 0) {

Log.v(TAG, "在move時候記錄下位置");

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

// 可以鬆手去刷新了

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 <headContentHeight)

&& (tempY - startY)> 0) {

state = PULL_To_REFRESH;

changeHeaderViewByState();

Log.v(TAG, "由鬆開刷新狀態轉變到下拉刷新狀態");

}

// 一下子推到頂了

else if (tempY - startY <= 0){

state = DONE;

changeHeaderViewByState();

Log.v(TAG, "由鬆開刷新狀態轉變到done狀態");

}

// 往下拉了，或者還沒有上推到屏幕頂部掩蓋head的地步

else {

// 不用進行特別的操作，只用更新paddingTop的值就行了

}

// 還沒有到達顯示鬆開刷新的時候,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 >=headContentHeight) {

state = RELEASE_To_REFRESH;

isBack = true;

changeHeaderViewByState();

Log.v(TAG, "由done或者下拉刷新狀態轉變到鬆開刷新");

}

// 上推到頂了

else if (tempY - startY <= 0){

state = DONE;

changeHeaderViewByState();

Log.v(TAG, "由DOne或者下拉刷新狀態轉變到done狀態");

}

// 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) {

headView.setPadding(0, -1 * headContentHeight

+ (tempY - startY) / RATIO, 0, 0);

}

// 更新headView的paddingTop

if (state == RELEASE_To_REFRESH) {

headView.setPadding(0, (tempY - startY) / RATIO

- headContentHeight, 0, 0);

}

break;

}

return super.onTouchEvent(event);

}

private void changeHeaderViewByState(){

switch (state) {

//鬆開刷新狀態

case RELEASE_To_REFRESH:

arrowImageView.setVisibility(View.VISIBLE);

progressBar.setVisibility(View.GONE);

tipsTextview.setVisibility(View.VISIBLE);

lastUpdatedTextView.setVisibility(View.VISIBLE);

arrowImageView.clearAnimation();

arrowImageView.startAnimation(animation);

tipsTextview.setText("鬆開刷新");

Log.v(TAG, "當前狀態，鬆開刷新");

break;

//下拉刷新

case PULL_To_REFRESH:

progressBar.setVisibility(View.GONE);

tipsTextview.setVisibility(View.VISIBLE);

lastUpdatedTextView.setVisibility(View.VISIBLE);

arrowImageView.clearAnimation();

arrowImageView.setVisibility(View.VISIBLE);

// 是由RELEASE_To_REFRESH狀態轉變來的

//箭頭反轉向上

if (isBack) {

isBack= false;

arrowImageView.clearAnimation();

arrowImageView.startAnimation(reverseAnimation);

tipsTextview.setText("下拉刷新");

} else {

tipsTextview.setText("下拉刷新");

}

Log.v(TAG, "當前狀態，下拉刷新");

break;

//刷新中狀態

case REFRESHING:

headView.setPadding(0, 0, 0, 0);

progressBar.setVisibility(View.VISIBLE);

arrowImageView.clearAnimation();

arrowImageView.setVisibility(View.GONE);

tipsTextview.setText("正在刷新...");

lastUpdatedTextView.setVisibility(View.VISIBLE);

Log.v(TAG,"當前狀態,正在刷新...");

break;

//刷新完畢

case DONE:

headView.setPadding(0, -1 * headContentHeight, 0,0);

progressBar.setVisibility(View.GONE);

arrowImageView.clearAnimation();

arrowImageView.setImageResource(R.drawable.goicon);

tipsTextview.setText("下拉刷新");

lastUpdatedTextView.setVisibility(View.VISIBLE);

Log.v(TAG, "當前狀態，done");

break;

}

public void setonRefreshListener(OnRefreshListenerrefreshListener) {

this.refreshListener =refreshListener;

isRefreshable = true;

}

public interface OnRefreshListener{

public void onRefresh();

}

public void onRefreshComplete(){

state = DONE;

SimpleDateFormat format=newSimpleDateFormat("yyyy年MM月dd日 HH:mm");

String date=format.format(newDate());

lastUpdatedTextView.setText("最近更新:"+ date);

changeHeaderViewByState();

}

private void onRefresh(){

if (refreshListener != null){

refreshListener.onRefresh();

}

//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 p =child.getLayoutParams();

if (p == null) {

p = new ViewGroup.LayoutParams(

ViewGroup.LayoutParams.FILL_PARENT,

ViewGroup.LayoutParams.WRAP_CONTENT);

}

int childWidthSpec = ViewGroup.getChildMeasureSpec(0,0 + 0, p.width);

int lpHeight = p.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 setAdapter(BaseAdapter adapter){

SimpleDateFormat format=newSimpleDateFormat("yyyy年MM月dd日 HH:mm");

String date=format.format(newDate());

lastUpdatedTextView.setText("最近更新:" +date);

super.setAdapter(adapter);

}

//activity裏面的實現，紅色是與ListView的不同方式，其他的都是類似

//packagesrc.com.lyg.refreshlist;

importjava.util.ArrayList;

importjava.util.HashMap;

importjava.util.List;

importsrc.com.lyg.R;

importsrc.com.lyg.refreshlist.PullToRefreshGridView.OnRefreshListener;

importandroid.app.Activity;

importandroid.os.AsyncTask;

importandroid.os.Bundle;

importandroid.view.Gravity;

importandroid.widget.FrameLayout.LayoutParams;

importandroid.widget.LinearLayout;

importandroid.widget.SimpleAdapter;

public classPullToRefreshGridViewActivity extends Activity {

private SimpleAdapter citySimpleAdapter;

public static LinearLayout head;

String[] areaName = new String[] { "南京", "蘇州", "無錫", "南通","徐州", "常州",

"揚州", "泰州", "鹽城", "鎮江", "淮安", "連雲港", "宿遷" };

// 存放13個城市

private List<HashMap<String,String>> cityList = newArrayList<HashMap<String,String>>();

public void onCreate(Bundle savedInstanceState){

super.onCreate(savedInstanceState);

setContentView(R.layout.grid_main);

//數據模擬城市初始化

for (int i = 0; i < areaName.length *6; i++) {

HashMap<String, String> hashMap =new HashMap<String,String>();

hashMap.put("id", String.valueOf(i));

hashMap.put("name", areaName[i % 13].toString());

cityList.add(hashMap);

}

final PullToRefreshGridView gridView =(PullToRefreshGridView)findViewById(R.id.order_form_grid);

head = (LinearLayout)findViewById(R.id.head);

LayoutParams p = newLayoutParams(LayoutParams.FILL_PARENT,LayoutParams.WRAP_CONTENT,Gravity.CENTER);

//獲取PullToRefreshGridView裏面的head佈局

head.addView(gridView.getView(), p);

citySimpleAdapter = new SimpleAdapter(this,cityList,

R.layout.weather_textview, new String[] { "name"},

new int[] { R.id.txtRepDlgCity });

gridView.setAdapter(citySimpleAdapter);

gridView.setonRefreshListener(new OnRefreshListener(){

public void onRefresh() {

new AsyncTask<Void, Void,Void>() {

protected Void doInBackground(Void... params) {

try {

Thread.sleep(1000);

} catch (Exception e) {

e.printStackTrace();

}

HashMap<String, String> hashMap =new HashMap<String,String>();

hashMap.put("id",String.valueOf(cityList.size()));

hashMap.put("name","刷新新增城市");

cityList.add(0,hashMap);

return null;

}

@Override

protected void onPostExecute(Void result){

citySimpleAdapter.notifyDataSetChanged();

gridView.onRefreshComplete();

}

}.execute();

}

});

}

//Activity裏面的XML文件在PullToRefreshGridView之前加了一個LinearLayout，用來添加從PullToRefreshGridView類中獲取到的head佈局

<?xmlversion="1.0"encoding="utf-8"?>

<LinearLayoutxmlns:android="http://schemas.android.com/apk/res/android"

android:layout_width="fill_parent"

android:layout_height="fill_parent"

android:orientation="vertical" >

<TextView

android:layout_width="fill_parent"

android:layout_height="50dp"

android:gravity="center"

android:text="GridView下拉刷新測試"/>

<LinearLayout

android:id="@+id/head"

android:layout_width="fill_parent"

android:layout_height="wrap_content">

</LinearLayout>

<src.com.lyg.refreshlist.PullToRefreshGridView

android:id="@+id/order_form_grid"

android:layout_width="fill_parent"

android:layout_height="wrap_content"

android:background="@android:color/darker_gray"

android:cacheColorHint="#00000000"

android:gravity="center"

android:horizontalSpacing="5dp"

android:numColumns="2"

android:paddingLeft="10dp"

android:paddingRight="20dp"

android:stretchMode="columnWidth"

android:verticalSpacing="5dp" >

</src.com.lyg.refreshlist.PullToRefreshGridView>

</LinearLayout>

HonB

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