现在的listview的下拉刷新各种各样，今天就来给大家提供一个比较简单的下拉刷新，自己动手敲吧。
大概的功能就是:listview下拉的时候提示下拉可以刷新，到一定的距离后提示松开可以刷新（旋转下拉箭头），手指离开屏幕后正在刷新...将提示箭头变成圆形进度条。
listview的下拉刷新的大概的几个步骤：
1、添加listview的头部界面 headerView;
2、监听listview的滚动事件 OnScrollListener();
3、监听listview的触摸事件 onTouch();
4、加载最新数据；
第一步 创建listview的头部布局 header
1、布局中包括了提示语的控件TextView,时间的Textview、有一个提示的图标ImageView、还有一个进度条ProgressBar默认不显示的。
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:paddingBottom="10dp"
android:paddingTop="10dp">
<LinearLayout
android:id="@+id/layout"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerInParent="true"
android:gravity="center"
android:orientation="vertical">
<TextView
android:id="@+id/tip"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="下拉可以刷新！" />
<TextView
android:id="@+id/lastupdate_time"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
</LinearLayout>
<ImageView
android:id="@+id/arrow"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginRight="20dp"
android:layout_toLeftOf="@id/layout"
android:src="@mipmap/pull_to_refresh_arrow" />
<ProgressBar
android:id="@+id/progress"
style="@style/Base.TextAppearance.AppCompat.Small"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginRight="20dp"
android:layout_toLeftOf="@id/layout"
android:visibility="gone" />
</RelativeLayout>
</LinearLayout>
2、创建好布局后将其添加在listview的头部
1> 继承listview，实现OnScrollListener的接口重写onScrollStateChanged()、onScroll()。
2> 在构造方法里添加布局文件headerView
LayoutInflater inflater = LayoutInflater.from(context);
header = inflater.inflate(R.layout.header_layout, null);
//添加头部的view
this.addHeaderView(header);
3> 头部的布局默认应该是隐藏的;实现的思路就是可以将头部布局的上边距设置成header高度的负值。
1.首先要得到header 的高度
/**
* 获取子控件高度和宽度
*
* @param view
*/
private void meadsureView(View view) {
ViewGroup.LayoutParams p = view.getLayoutParams();
if (p == null) {
p = new ViewGroup.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.WRAP_CONTENT);
}
int width = ViewGroup.getChildMeasureSpec(0, 0, p.width);
int height;
int tempHeight = p.height;
if (tempHeight > 0) {
height = MeasureSpec.makeMeasureSpec(tempHeight, MeasureSpec.EXACTLY);
} else {
height = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED);
}
view.measure(width, height);
}
2.设置header的上边距，上边距的值应该为header的负值。
/**
* 设置header布局的上边距
*
* @param topPadding
*/
private void topPadding(int topPadding) {
header.setPadding(header.getPaddingLeft(), topPadding, header.getPaddingRight(), header.getPaddingBottom());
header.invalidate();
}
3.初始化header
/**
* 初始化界面，添加顶部布局文件到listview
*
* @param context
*/
private void initView(Context context) {
LayoutInflater inflater = LayoutInflater.from(context);
header = inflater.inflate(R.layout.header_layout, null);
meadsureView(header);
headerHeight = header.getMeasuredHeight();
topPadding(-headerHeight);
//添加头部的view
this.addHeaderView(header);
this.setOnScrollListener(this);
}
通过以上三步我们就可以成功就header隐藏掉。
第二步 监听listview的滚动事件
1、初始记得设置OnScrollListener的监听事件this.setOnScrollListener(this);
2、重写下面两个方法
@Override
public void onScrollStateChanged(AbsListView absListView, int scrollState) {
this.scrollState = scrollState;
}
@Override
public void onScroll(AbsListView absListView, int firsVisibleItem, int visibleItemCount, int totalItemCount) {
//firsVisibleItem是否是第一条也就意味着是否在listview的最顶端从而判断header的显示隐藏以及之后的刷新等等
this.firsVisibleItem = firsVisibleItem;
}
3、监听用户的（onTouchEvent()）手势判断是按下、移动、抬起...
1> //isRemark标记的是否在当前的listview的顶端按下的
//startY是按下时的Y值
//state当前操作的状态
@Override
public boolean onTouchEvent(MotionEvent ev) {
switch (ev.getAction()) {
case MotionEvent.ACTION_DOWN:
if (firsVisibleItem == 0) {
isRemark = true;
startY = (int) ev.getY();
}
break;
case MotionEvent.ACTION_MOVE:
onMove(ev);
break;
case MotionEvent.ACTION_UP:
if (state == RELESE) {
state = REFLAHING;
//添加数据
reflashViewByState();
iReflashLisener.onReflash();
} else if (state == PULL) {
state = NONE;
isRemark = false;
reflashViewByState();
}
break;
}
return super.onTouchEvent(ev);
}
2>根据移动的距离判断在移动过程的状态。正常、下拉、松开、刷新四个状态。
//space是移动的距离
状态判断
space > 0 正常转下拉状态 (ps：下拉可以刷新)
space > headerHeight+30&&scrollState == SCROLL_STATE_TOUCH_SCROLL 下拉转松开状态 (ps：松开可以刷新)
space < headerHeight+30 松开转下拉状态 (ps：下拉可以刷新)
space <= 0 下拉转正常状态 (ps：header隐藏)
/**
* 判断listview在移动过程中的操作
*
* @param ev
*/
private void onMove(MotionEvent ev) {
if (!isRemark) {
return;
}
int tempY = (int) ev.getY();
int space = tempY - startY;
int topPadding = space - headerHeight;
switch (state) {
case NONE:
if (space > 0) {
state = PULL;
reflashViewByState();
}
break;
case PULL:
topPadding(topPadding);
if (space > headerHeight + 30 && scrollState == SCROLL_STATE_TOUCH_SCROLL) {
state = RELESE;
reflashViewByState();
}
break;
case RELESE:
topPadding(topPadding);
if (space < headerHeight + 30) {
state = PULL;
reflashViewByState();
} else if (space <= 0) {
state = NONE;
isRemark = false;
reflashViewByState();
}
break;
}
}
3>根据当前的操作状态（正常、下拉、松开、刷新）判断header的显示内容：
/**
* 判断当前状态更改header的布局
*/
private void reflashViewByState() {
TextView tip = (TextView) header.findViewById(R.id.tip);
ImageView arrow = (ImageView) header.findViewById(R.id.arrow);
ProgressBar progressBar = (ProgressBar) header.findViewById(R.id.progress);
RotateAnimation anim = new RotateAnimation(0, 180,
RotateAnimation.RELATIVE_TO_SELF, 0.5f,
RotateAnimation.RELATIVE_TO_SELF, 0.5f);
anim.setDuration(500);
anim.setFillAfter(true);
RotateAnimation anim1 = new RotateAnimation(180, 0,
RotateAnimation.RELATIVE_TO_SELF, 0.5f,
RotateAnimation.RELATIVE_TO_SELF, 0.5f);
anim1.setDuration(500);
anim1.setFillAfter(true);
switch (state) {
case NONE:
arrow.clearAnimation();
topPadding(-headerHeight);
break;
case PULL:
arrow.setVisibility(View.VISIBLE);
progressBar.setVisibility(View.GONE);
tip.setText("下拉可以刷新！");
arrow.clearAnimation();
arrow.setAnimation(anim1);
break;
case RELESE:
arrow.setVisibility(View.VISIBLE);
progressBar.setVisibility(View.GONE);
tip.setText("松开可以刷新！");
arrow.clearAnimation();
arrow.setAnimation(anim);
break;
case REFLAHING:
topPadding(50);
arrow.setVisibility(View.GONE);
progressBar.setVisibility(View.VISIBLE);
tip.setText("正在刷新...");
arrow.clearAnimation();
break;
}
}
4、为刷新数据提供一个接口，然后通过activity实现重现onReflash()方法。
/**
* 刷新数据接口
*/
public interface IReflashLisener {
void onReflash();
}
activity调用的结果：
@Override
public void onReflash() {
Handler handler = new Handler();
handler.postDelayed(new Runnable() {
@Override
public void run() {
//后台请求数据
addReflashData();
//通知界面
myAdapter.notifyDataSetChanged();
Toast.makeText(MainActivity.this, "刷新成功", Toast.LENGTH_SHORT).show();
mList.reflashComplete();
}
}, 2000);
}
下面是源码：
package com.nz.zdd.zlistview.widget;
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.RotateAnimation;
import android.widget.AbsListView;
import android.widget.AbsListView.OnScrollListener;
import android.widget.ImageView;
import android.widget.ListView;
import android.widget.ProgressBar;
import android.widget.TextView;
import com.nz.zdd.zlistview.R;
import java.text.SimpleDateFormat;
import java.util.Date;
/**
* Created by zdd on /9/8.
*/
public class ZReFlashListView extends ListView implements OnScrollListener {
/**
* 顶部布局文件
*/
private View header;
/**
* 顶部布局文件的高度
*/
private int headerHeight;
/**
* 当前item的位置
*/
private int firsVisibleItem;
/**
* 判断是否是listview最顶端按下的
*/
public boolean isRemark;
/**
* 记录按下的Y值
*/
private int startY;
/**
* 当前状态
*/
private int state;
/**
* 正常状态
*/
private final int NONE = 0;
/**
* 提示下拉状态
*/
private final int PULL = 1;
/**
* 松开提示状态
*/
private final int RELESE = 2;
/**
* 正在刷新状态
*/
private final int REFLAHING = 3;
/**
* lsitview当前滚动状态
*/
private int scrollState;
public IReflashLisener iReflashLisener;
public void setInterface(IReflashLisener iReflashLisener) {
this.iReflashLisener = iReflashLisener;
}
public ZReFlashListView(Context context) {
super(context);
initView(context);
}
public ZReFlashListView(Context context, AttributeSet attrs) {
super(context, attrs);
initView(context);
}
public ZReFlashListView(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
initView(context);
}
/**
* 初始化界面，添加顶部布局文件到listview
*
* @param context
*/
private void initView(Context context) {
LayoutInflater inflater = LayoutInflater.from(context);
header = inflater.inflate(R.layout.header_layout, null);
meadsureView(header);
headerHeight = header.getMeasuredHeight();
topPadding(-headerHeight);
//添加头部的view
this.addHeaderView(header);
this.setOnScrollListener(this);
}
/**
* 获取子控件高度和宽度
*
* @param view
*/
private void meadsureView(View view) {
ViewGroup.LayoutParams p = view.getLayoutParams();
if (p == null) {
p = new ViewGroup.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.WRAP_CONTENT);
}
int width = ViewGroup.getChildMeasureSpec(0, 0, p.width);
int height;
int tempHeight = p.height;
if (tempHeight > 0) {
height = MeasureSpec.makeMeasureSpec(tempHeight, MeasureSpec.EXACTLY);
} else {
height = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED);
}
view.measure(width, height);
}
/**
* 设置header布局的上边距
*
* @param topPadding
*/
private void topPadding(int topPadding) {
header.setPadding(header.getPaddingLeft(), topPadding, header.getPaddingRight(), header.getPaddingBottom());
header.invalidate();
}
@Override
public boolean onTouchEvent(MotionEvent ev) {
switch (ev.getAction()) {
case MotionEvent.ACTION_DOWN:
if (firsVisibleItem == 0) {
isRemark = true;
startY = (int) ev.getY();
}
break;
case MotionEvent.ACTION_MOVE:
onMove(ev);
break;
case MotionEvent.ACTION_UP:
if (state == RELESE) {
state = REFLAHING;
//添加数据
reflashViewByState();
iReflashLisener.onReflash();
} else if (state == PULL) {
state = NONE;
isRemark = false;
reflashViewByState();
}
break;
}
return super.onTouchEvent(ev);
}
/**
* 判断listview在移动过程中的操作
*
* @param ev
*/
private void onMove(MotionEvent ev) {
if (!isRemark) {
return;
}
int tempY = (int) ev.getY();
int space = tempY - startY;
int topPadding = space - headerHeight;
switch (state) {
case NONE:
if (space > 0) {
state = PULL;
reflashViewByState();
}
break;
case PULL:
topPadding(topPadding);
if (space > headerHeight + 30 && scrollState == SCROLL_STATE_TOUCH_SCROLL) {
state = RELESE;
reflashViewByState();
}
break;
case RELESE:
topPadding(topPadding);
if (space < headerHeight + 30) {
state = PULL;
reflashViewByState();
} else if (space <= 0) {
state = NONE;
isRemark = false;
reflashViewByState();
}
break;
}
}
/**
* 判断当前状态更改header的布局
*/
private void reflashViewByState() {
TextView tip = (TextView) header.findViewById(R.id.tip);
ImageView arrow = (ImageView) header.findViewById(R.id.arrow);
ProgressBar progressBar = (ProgressBar) header.findViewById(R.id.progress);
RotateAnimation anim = new RotateAnimation(0, 180,
RotateAnimation.RELATIVE_TO_SELF, 0.5f,
RotateAnimation.RELATIVE_TO_SELF, 0.5f);
anim.setDuration(500);
anim.setFillAfter(true);
RotateAnimation anim1 = new RotateAnimation(180, 0,
RotateAnimation.RELATIVE_TO_SELF, 0.5f,
RotateAnimation.RELATIVE_TO_SELF, 0.5f);
anim1.setDuration(500);
anim1.setFillAfter(true);
switch (state) {
case NONE:
arrow.clearAnimation();
topPadding(-headerHeight);
break;
case PULL:
arrow.setVisibility(View.VISIBLE);
progressBar.setVisibility(View.GONE);
tip.setText("下拉可以刷新！");
arrow.clearAnimation();
arrow.setAnimation(anim1);
break;
case RELESE:
arrow.setVisibility(View.VISIBLE);
progressBar.setVisibility(View.GONE);
tip.setText("松开可以刷新！");
arrow.clearAnimation();
arrow.setAnimation(anim);
break;
case REFLAHING:
topPadding(50);
arrow.setVisibility(View.GONE);
progressBar.setVisibility(View.VISIBLE);
tip.setText("正在刷新...");
arrow.clearAnimation();
break;
}
}
/**
* 获取成功后
*/
public void reflashComplete() {
state = NONE;
isRemark = false;
reflashViewByState();
SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy年MM月dd日 hh:mm:ss");
Date date = new Date(System.currentTimeMillis());
String time = simpleDateFormat.format(date);
TextView lastupdate_time = (TextView) header.findViewById(R.id.lastupdate_time);
lastupdate_time.setText(time);
}
@Override
public void onScrollStateChanged(AbsListView absListView, int scrollState) {
this.scrollState = scrollState;
}
@Override
public void onScroll(AbsListView absListView, int firsVisibleItem, int visibleItemCount, int totalItemCount) {
this.firsVisibleItem = firsVisibleItem;
}
/**
* 刷新数据接口
*/
public interface IReflashLisener {
void onReflash();
}
}
MainActivity中调用：
package com.nz.zdd.zlistview;
import android.app.Activity;
import android.os.Handler;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.ListView;
import android.widget.Toast;
import com.nz.zdd.zlistview.adapter.MyAdapter;
import com.nz.zdd.zlistview.entity.Person;
import com.nz.zdd.zlistview.widget.ZReFlashListView;
import java.util.ArrayList;
import java.util.List;
public class MainActivity extends Activity implements ZReFlashListView.IReflashLisener {
private ZReFlashListView mList;
private Person mPerson;
private MyAdapter myAdapter;
private List<Person> mListData = new ArrayList<>();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
addData();
initView();
}
private void initView() {
mList = (ZReFlashListView) findViewById(R.id.listData);
mList.setInterface(this);
myAdapter = new MyAdapter(mListData, MainActivity.this);
mList.setAdapter(myAdapter);
myAdapter.notifyDataSetChanged();
}
private void addData() {
for (int i = 0; i < 20; i++) {
mPerson = new Person();
mPerson.setName("张三");
mPerson.setSex("男");
mPerson.setAge(i);
mListData.add(mPerson);
}
}
@Override
public void onReflash() {
Handler handler = new Handler();
handler.postDelayed(new Runnable() {
@Override
public void run() {
//后台请求数据
addReflashData();
//通知界面
myAdapter.notifyDataSetChanged();
Toast.makeText(MainActivity.this, "刷新成功", Toast.LENGTH_SHORT).show();
mList.reflashComplete();
}
}, 2000);
}
private void addReflashData() {
for (int i = 0; i < 5; i++) {
mPerson = new Person();
mPerson.setName("李四");
mPerson.setSex("女");
mPerson.setAge(i);
mListData.add(0,mPerson);
}
}
}
好了基本上的功能都已经实现了，如果有喜欢的可以试试。。讲的不对的地方看看代码。欢迎留言。
