現在QQ空間和新浪微博ListView下拉刷新做的比較炫,正好公司也有這樣的需求,實現起來還是相對簡單的。關鍵是要自定義一個ListView頭部(初始化的時候裏面的控件是不可見的),然後在點擊、拖動、鬆開的時候觸發事件,顯示ListView頭,計算出拖拽的距離,跟ListView頭的高度做比較,以此來顯示對應的ListView頭裏的控件(下拉圖標、提示文字、圓形進度條等)。好了,下面貼出效果圖:
好,開始上代碼,先是佈局文件main.xml,沒什麼好說的:
<?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"
android:background="@color/mainColor">
<!-- 這裏是自定義的ListView -->
<com.focustech.android.CustomListView
android:id="@+id/list"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
/>
</LinearLayout>
ListView頭佈局head.xml:
<?xmlversion="1.0"encoding="utf-8"?>
<LinearLayoutxmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<RelativeLayout
android:id="@+id/head_contentLayout"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:paddingLeft="30dp">
<FrameLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_centerVertical="true">
<ImageView
android:id="@+id/head_arrowImageView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:src="@drawable/ic_pulltorefresh_arrow"/>
<ProgressBar
android:id="@+id/head_progressBar"
style="?android:attr/progressBarStyleSmall"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:visibility="gone"/>
</FrameLayout>
<LinearLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:gravity="center_horizontal"
android:orientation="vertical">
<TextView
android:id="@+id/head_tipsTextView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="下拉可以刷新"
android:textColor="#ffffff"
android:textSize="20sp"/>
<TextView
android:id="@+id/head_lastUpdatedTextView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="最近更新"
android:textColor="#cc6600"
android:textSize="10sp"/>
</LinearLayout>
</RelativeLayout>
</LinearLayout>
ListView item項佈局listview_item.xml:
<?xmlversion="1.0"encoding="utf-8"?>
<LinearLayoutxmlns:Android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<ImageView
android:id="@+id/imageView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:src="@drawable/pretty_girl"
/>
<TextView
android:id="@+id/textview"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
/>
</LinearLayout>
清單文件也貼出來吧,其實就是自動生成的,什麼都不用改:
<?xmlversion="1.0"encoding="utf-8"?>
<manifestxmlns:android="http://schemas.android.com/apk/res/android"
package="com.focustech.android"
android:versionCode="1"
android:versionName="1.0">
<uses-sdkandroid:minSdkVersion="14"/>
<application
android:icon="@drawable/ic_launcher"
android:label="@string/app_name">
<activity
android:label="@string/app_name"
android:name="com.focustech.android.MainActivity">
<intent-filter>
<actionandroid:name="android.intent.action.MAIN"/>
<categoryandroid:name="android.intent.category.LAUNCHER"/>
</intent-filter>
</activity>
</application>
</manifest>
此Demo的Activity:
package com.focustech.android;
import android.app.Activity;
import android.database.DataSetObserver;
import android.graphics.Color;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ListAdapter;
import android.widget.TextView;
import com.focustech.android.CustomListView.OnRefreshListener;
import com.focustech.android.R;
publicclass MainActivity extends Activity {
private ListAdapter adapter;
int size = 10;
publicvoid onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
final CustomListView list = (CustomListView) findViewById(R.id.list);
adapter = new ListAdapter() {
publicvoid unregisterDataSetObserver(DataSetObserver arg0) {
}
publicvoid registerDataSetObserver(DataSetObserver arg0) {
}
publicboolean isEmpty() {
returnfalse;
}
publicboolean hasStableIds() {
returnfalse;
}
publicint getViewTypeCount() {
return1;
}
public View getView(int position, View convertView, ViewGroup parent) {
convertView = LayoutInflater.from(getApplicationContext())
.inflate(R.layout.listview_item, null);
TextView mTextView = (TextView) convertView
.findViewById(R.id.textview);
mTextView.setText("pretty girl" + position);
mTextView.setTextColor(Color.RED);
return convertView;
}
publicint getItemViewType(int arg0) {
return arg0;
}
publiclong getItemId(int arg0) {
return arg0;
}
public Object getItem(int arg0) {
returnnull;
}
publicint getCount() {
return size;
}
@Override
publicboolean isEnabled(int position) {
returnfalse;
}
@Override
publicboolean areAllItemsEnabled() {
returnfalse;
}
};
list.setAdapter(adapter);
// 在list上註冊自定義的監聽器
list.setonRefreshListener(new OnRefreshListener() {
publicvoid onRefresh() {
new Thread(new Runnable() {
publicvoid run() {
try {
Thread.sleep(1000);
} catch (Exception e) {
}
runOnUiThread(new Runnable() {
publicvoid run() {
list.onRefreshComplete();
}
});
size++;
}
}).start();
}
});
}
}
實現了OnScrollListener的自定義ListView:
package com.focustech.Android;
import java.util.Date;
import android.content.Context;
import android.util.AttributeSet;
import android.util.Log;
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;
import com.focustech.android.R;
publicclass CustomListView extends ListView implements OnScrollListener {
// 鬆開刷新標誌
privatefinalstaticint RELEASE_To_REFRESH = 0;
// 下拉刷新標誌
privatefinalstaticint PULL_To_REFRESH = 1;
// 正在刷新標誌
privatefinalstaticint REFRESHING = 2;
// 刷新完成標誌
privatefinalstaticint DONE = 3;
private LayoutInflater inflater;
private LinearLayout headView;
private TextView tipsTextview;
private TextView lastUpdatedTextView;
private ImageView arrowImageView;
private ProgressBar progressBar;
// 用來設置箭頭圖標動畫效果
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
privateboolean isRecored;
privateint headContentWidth;
privateint headContentHeight;
privateint startY;
privateint firstItemIndex;
privateint state;
privateboolean isBack;
public OnRefreshListener refreshListener;
privatefinalstatic String TAG = "Monitor Current Infomation";
public CustomListView(Context context, AttributeSet attrs) {
super(context, attrs);
init(context);
}
privatevoid init(Context context) {
inflater = LayoutInflater.from(context);
headView = (LinearLayout) inflater.inflate(R.layout.head, null);
arrowImageView = (ImageView) headView
.findViewById(R.id.head_arrowImageView);
arrowImageView.setMinimumWidth(50);
arrowImageView.setMinimumHeight(50);
progressBar = (ProgressBar) headView
.findViewById(R.id.head_progressBar);
tipsTextview = (TextView) headView.findViewById(R.id.head_tipsTextView);
lastUpdatedTextView = (TextView) headView
.findViewById(R.id.head_lastUpdatedTextView);
measureView(headView);
headContentHeight = headView.getMeasuredHeight();
headContentWidth = headView.getMeasuredWidth();
headView.setPadding(0, -1 * headContentHeight, 0, 0);
headView.invalidate();
Log.v("size", "width:" + headContentWidth + " height:"
+ headContentHeight);
addHeaderView(headView);
setOnScrollListener(this);
animation = new RotateAnimation(0, -180,
RotateAnimation.RELATIVE_TO_SELF, 0.5f,
RotateAnimation.RELATIVE_TO_SELF, 0.5f);
animation.setInterpolator(new LinearInterpolator());
animation.setDuration(500);
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(500);
reverseAnimation.setFillAfter(true);
}
publicvoid onScroll(AbsListView arg0, int firstVisiableItem, int arg2,
int arg3) {
firstItemIndex = firstVisiableItem;
}
publicvoid onScrollStateChanged(AbsListView arg0, int arg1) {
}
publicboolean onTouchEvent(MotionEvent event) {
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
if (firstItemIndex == 0 && !isRecored) {
startY = (int) event.getY();
isRecored = true;
Log.v(TAG, "記錄按下時的位置");
}
break;
case MotionEvent.ACTION_UP:
if (state != REFRESHING) {
if (state == DONE) {
Log.v(TAG, "什麼都不做");
}
if (state == PULL_To_REFRESH) {
state = DONE;
changeHeaderViewByState();
Log.v(TAG, "由下拉刷新狀態到刷新完成狀態");
}
if (state == RELEASE_To_REFRESH) {
state = REFRESHING;
changeHeaderViewByState();
onRefresh();
Log.v(TAG, "由鬆開刷新狀態,到刷新完成狀態");
}
}
isRecored = false;
isBack = false;
break;
case MotionEvent.ACTION_MOVE:
int tempY = (int) event.getY();
if (!isRecored && firstItemIndex == 0) {
Log.v(TAG, "記錄拖拽時的位置");
isRecored = true;
startY = tempY;
}
if (state != REFRESHING && isRecored) {
// 可以鬆開刷新了
if (state == RELEASE_To_REFRESH) {
// 往上推,推到屏幕足夠掩蓋head的程度,但還沒有全部掩蓋
if ((tempY - startY < 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
elseif (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,或者還沒有上推到屏幕頂部掩蓋head
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) {
// 下拉到可以進入RELEASE_TO_REFRESH的狀態
if (tempY - startY >= 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
elseif (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), 0, 0);
headView.invalidate();
}
// 更新headView的paddingTop
if (state == RELEASE_To_REFRESH) {
headView.setPadding(0, tempY - startY - headContentHeight,
0, 0);
headView.invalidate();
}
}
break;
}
returnsuper.onTouchEvent(event);
}
// 當狀態改變時候,調用該方法,以更新界面
privatevoid 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("鬆開可以刷新");
Log.v(TAG, "當前狀態,鬆開刷新");
break;
case PULL_To_REFRESH:
progressBar.setVisibility(View.GONE);
tipsTextview.setVisibility(View.VISIBLE);
lastUpdatedTextView.setVisibility(View.VISIBLE);
arrowImageView.clearAnimation();
arrowImageView.setVisibility(View.VISIBLE);
if (isBack) {
isBack = false;
arrowImageView.clearAnimation();
arrowImageView.startAnimation(reverseAnimation);
tipsTextview.setText("下拉可以刷新");
} else {
tipsTextview.setText("下拉可以刷新");
}
Log.v(TAG, "當前狀態,下拉刷新");
break;
case REFRESHING:
headView.setPadding(0, 0, 0, 0);
headView.invalidate();
progressBar.setVisibility(View.VISIBLE);
arrowImageView.clearAnimation();
arrowImageView.setVisibility(View.GONE);
tipsTextview.setText("正在刷新,請稍後...");
lastUpdatedTextView.setVisibility(View.GONE);
Log.v(TAG, "當前狀態,正在刷新...");
break;
case DONE:
headView.setPadding(0, -1 * headContentHeight, 0, 0);
headView.invalidate();
progressBar.setVisibility(View.GONE);
arrowImageView.clearAnimation();
// 此處更換圖標
arrowImageView.setImageResource(R.drawable.ic_pulltorefresh_arrow);
tipsTextview.setText("下拉可以刷新");
lastUpdatedTextView.setVisibility(View.VISIBLE);
Log.v(TAG, "當前狀態,done");
break;
}
}
publicvoid setonRefreshListener(OnRefreshListener refreshListener) {
this.refreshListener = refreshListener;
}
publicinterface OnRefreshListener {
publicvoid onRefresh();
}
publicvoid onRefreshComplete() {
state = DONE;
lastUpdatedTextView.setText("最近更新:" + new Date().toLocaleString());
changeHeaderViewByState();
}
privatevoid onRefresh() {
if (refreshListener != null) {
refreshListener.onRefresh();
}
}
// 此處是“估計”headView的width以及height
privatevoid 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);
}
}