【移动应用开发技术】android 安卓自定义listview实现下拉刷新

【移动应用开发技术】android安卓自定义listview实现下拉刷新

【1】、重写listViewpublic

class

MyListView

extends

ListView

implements

OnScrollListener

{

private

final

static

int

RELEASE_To_REFRESH

=

0;//

下拉过程的状态值

private

final

static

int

PULL_To_REFRESH

=

1;

//

从下拉返回到不刷新的状态值

private

final

static

int

REFRESHING

=

2;//

正在刷新的状态值

private

final

static

int

DONE

=

3;

private

final

static

int

LOADING

=

4;

//

实际的padding的距离与界面上偏移距离的比例

private

final

static

int

RATIO

=

3;

private

LayoutInflater

inflater;

//

ListView头部下拉刷新的布局

private

LinearLayout

headerView;

private

TextView

lvHeaderTipsTv;

private

TextView

lvHeaderLastUpdatedTv;

private

ImageView

lvHeaderArrowIv;

private

ProgressBar

lvHeaderProgressBar;

//

定义头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;

//

用于保证startY的值在一个完整的touch事件中只被记录一次

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);

//

设置下拉刷新图标的最小高度和宽度

lvHeaderArrowIv.setMinimumWidth(70);

lvHeaderArrowIv.setMinimumHeight(50);

lvHeaderProgressBar

=

(ProgressBar)

headerView

.findViewById(R.id.lvHeaderProgressBar);

measureView(headerView);

headerContentHeight

=

headerView.getMeasuredHeight();

//

设置内边距，正好距离顶部为一个负的整个布局的高度，正好把头部隐藏

headerView.setPadding(0,

-1

*

headerContentHeight,

0,

0);

//

重绘一下

headerView.invalidate();

//

将下拉刷新的布局加入ListView的顶部

addHeaderView(headerView,

null,

false);

//

设置滚动监听事件

setOnScrollListener(this);

//

设置旋转动画事件

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);

//

一开始的状态就是下拉刷新完的状态，所以为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();//

手指按下时记录当前位置

}

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)

{

//

保证在设置padding的过程中，当前的位置一直是在head，否则如果当列表超出屏幕的话，当在上推的时候，列表会同时进行滚动

//

可以松手去刷新了

if

(state

==

RELEASE_To_REFRESH)

{

setSelection(0);

//

往上推了，推到了屏幕足够掩盖head的程度，但是还没有推到全部掩盖的地步

if

(((tempY

-

startY)

/

RATIO

<

headerContentHeight)//

由松开刷新状态转变到下拉刷新状态

&&

(tempY

-

startY)

>

0)

{

state

=

PULL_To_REFRESH;

changeHeaderViewByState();

}

//

一下子推到顶了

else

if

(tempY

-

startY

<=

0)

{//

由松开刷新状态转变到done状态

state

=

DONE;

changeHeaderViewByState();

}

}

//

还没有到达显示松开刷新的时候,DONE或者是PULL_To_REFRESH状态

if

(state

==

PULL_To_REFRESH)

{

setSelection(0);

//

下拉到可以进入RELEASE_TO_REFRESH的状态

if

((tempY

-

startY)

/

RATIO

>=

headerContentHeight)

{//

由done或者下拉刷新状态转变到松开刷新

state

=

RELEASE_To_REFRESH;

isBack

=

true;

changeHeaderViewByState();

}

//

上推到顶了

else

if

(tempY

-

startY

<=

0)

{//

由DOne或者下拉刷新状态转变到done状态

state

=

DONE;

changeHeaderViewByState();

}

}

//

done状态下

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);

}

//

当状态改变时候，调用该方法，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();//

清除动画

lvHeaderArrowIv.startAnimation(animation);//

开始动画效果

lvHeaderTipsTv.setText("松开刷新");

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状态转变来的

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;

}

}

//

此方法直接照搬自网络上的一个下拉刷新的demo，此处是“估计”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(BaseAdapter

adapter)

{

lvHeaderLastUpdatedTv.setText("最近更新:"

+

new

Date().toLocaleString());

super.setAdapter(adapter);

}

}【2】刷新头部xml文件lv_header.xml<?xml

version="1.0"

encoding="utf-8"?>

<!--

ListView的头部

-->

<LinearLayout

xmlns:android="/apk/res/android"

android:layout_width="fill_parent"

android:layout_height="wrap_content"

android:background="#000000"

>

<!--

内容

-->

<RelativeLayout

android:id="@+id/head_contentLayout"

android:layout_width="fill_parent"

android:layout_height="wrap_content"

android:paddingLeft="30dp"

>

<!--

箭头图像、进度条

-->

<FrameLayout

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:layout_alignParentLeft="true"

android:layout_centerVertical="true"

>

<!--

箭头

-->

<ImageView

android:id="@+id/lvHeaderArrowIv"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:layout_gravity="center"

android:src="@drawable/arrow"

/>

<!--

进度条

-->

<ProgressBar

android:id="@+id/lvHeaderProgressBar"

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"

andr