andorid 下拉刷新

1:android的下拉刷新操做是須要一個ListView,經過onTouchEvent來判斷用戶的手勢操做,用戶觸摸屏幕而且下拉時,當下拉超過指定的設定高度時就提示用戶進行刷新。android

2:當進行刷新時,header顯示加載條,並提示用戶上次更新的時間。佈局

3:數據加載結束後,經過handle刷新界面,並隱藏header,至此下拉刷新結束。spa

android onTouchEvent事件代碼:code

    public boolean onTouchEvent(MotionEvent event)
    {
        if (isRefreshable)
        {
            switch (event.getAction())
            {
                case MotionEvent.ACTION_DOWN:
                    if (firstItemIndex == 0 && !isRecored)
                    {
                        isRecored = true;
                        startY = (int) event.getY();//獲取用戶觸摸位置
                    }
                    break;
                case MotionEvent.ACTION_UP:
                    if (state != REFRESHING && state != LOADING)
                    {
                        if (state == DONE)
                        {
                        }
                        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的過程當中,當前的位置一直是在head,不然若是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
                        // 能夠鬆手去刷新了
                        if (state == RELEASE_To_REFRESH)
                        {
                            setSelection(0);
                            // 往上推了,推到了屏幕足夠掩蓋head的程度,可是尚未推到所有掩蓋的地步
                            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");
                            }
                            // 一會兒推到頂了
                            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,或者尚未上推到屏幕頂部掩蓋head的地步
                            else
                            {
                                // 不用進行特別的操做,只用更新paddingTop的值就好了
                            }
                        }
                        // 尚未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);
                            // 下拉到能夠進入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);
    }
// 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:
                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");
                date = new Date().toLocaleString();//記錄上次更新的時間
                break;
            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
                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;
            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;
            case DONE:
                headView.setPadding(0, -1 * headContentHeight, 0, 0);
                progressBar.setVisibility(View.GONE);
                arrowImageView.clearAnimation();
                arrowImageView.setImageResource(R.drawable.arrow);
                tipsTextview.setText("下拉刷新");
                lastUpdatedTextView.setVisibility(View.VISIBLE);
                Log.v(TAG, "當前狀態,done");
                break;
        }
    }

佈局文件:xml

<?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="wrap_content">
  <RelativeLayout android:layout_width="fill_parent" android:layout_height="wrap_content"
      android:id="@+id/head_contentLayout" 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:layout_width="wrap_content" android:layout_height="wrap_content"
              android:layout_gravity="center" android:src="@drawable/arrow"
              android:id="@+id/head_arrowImageView"/>
          <!-- 進度條 -->
          <ProgressBar android:layout_width="wrap_content" android:layout_height="wrap_content"
                style="?android:attr/progressBarStyleSmall" android:layout_gravity="center"
                android:id="@+id/head_progressBar" 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:orientation="vertical"
          android:gravity="center_horizontal">
          <!-- 提示 -->
          <TextView android:layout_width="wrap_content" android:layout_height="wrap_content"
              android:text="下拉刷新" android:textColor="@color/white" android:textSize="20dip"
                android:id="@+id/head_tipsTextView"/>
          <!-- 最近更新 -->
          <TextView android:layout_width="wrap_content" android:layout_height="wrap_content"
              android:id="@+id/head_lastUpdatedTextView" android:text="上次更新"
                android:textColor="@color/white" android:textSize="12dip"/>
      </LinearLayout>
  </RelativeLayout>
</LinearLayout>

效果圖:
blog

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