Android开发之细说ListView上拉加载，下拉刷新过程

摘要学习记下的笔记下拉刷新-------    1.addHeaderView必须在setAdapter之前调用    2.将paddingTop设置一个headerView高度的负值去隐藏它       getHeight()和getMeasuredHeight()的区别：    getMeasuredHeight():获取测量完的高度，只要在onMeasure方法执行完，就可以用                        它获取到宽高，在自定义控件内部多使用这个                        使用view.measure(0,0)方法可以主动通知系统去测量，然后就                        可以直接使用它获取宽高    getHeight()：必须在onLayout方法执行完后，才能获得宽高                view.getViewTreeObserver().addOnGlobalLayoutListener(new OnGlobalLayoutListener() {                    @Override                    public void onGlobalLayout() {                    headerView.getViewTreeObserver().removeGlobalOnLayoutListener(this);                    int headerViewHeight = headerView.getHeight();                    //直接可以获取宽高            }        });    3.setSelection(position);将对应位置的item放置到屏幕顶端 第一步：制作一个旋转的箭头动画indeterminate_drawable.xml

<?xml version="1.0" encoding="utf-8"?>
<rotate xmlns:android="http://schemas.android.com/apk/res/android"
android:drawable="@drawable/indicate_rotate"
android:fromDegrees="0"  从0度开始旋转
android:pivotX="50%"     参照点自身X轴一半
android:pivotY="50%"     自身Y轴一半
android:toDegrees="360"/>   旋转360度

第二步：下拉加载布局文件layout_header.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:gravity="center_horizontal"
android:orientation="horizontal" >

<RelativeLayout android:layout_width="wrap_content"
android:layout_marginTop="10dp"
android:layout_marginBottom="10dp"
android:layout_height="wrap_content">

<ImageView android:layout_width="wrap_content"
android:layout_centerInParent="true"
android:id="@+id/iv_arrow"
android:background="@drawable/indicator_arrow"
android:layout_height="wrap_content"/>

<ProgressBar android:layout_width="30dp"
android:layout_centerInParent="true"
android:layout_height="30dp"
android:visibility="invisible"    初始化不可见
android:id="@+id/pb_rotate"
android:indeterminateDuration="1000"    旋转周期1秒
android:indeterminateDrawable="@drawable/indeterminate_drawable"   设置刚刚自定义的旋转箭头动画
/>

</RelativeLayout>

<LinearLayout android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="10dp"
android:layout_marginBottom="10dp"
android:gravity="center"
android:layout_marginLeft="15dp"
android:orientation="vertical">
<TextView android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textSize="20sp"
android:id="@+id/tv_state"
android:textColor="#aa000000"
android:text="下拉刷新"/>
<TextView android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textSize="14sp"
android:id="@+id/tv_time"
android:textColor="@android:color/darker_gray"
android:text="最后刷新："/>

</LinearLayout>

</LinearLayout>

第三步：上拉加载布局文件layout_footer.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:gravity="center_horizontal"
android:orientation="horizontal" >

<RelativeLayout android:layout_width="wrap_content"
android:layout_marginTop="10dp"
android:layout_marginBottom="10dp"
android:layout_height="wrap_content">

<ImageView android:layout_width="wrap_content"
android:layout_centerInParent="true"
android:id="@+id/iv_arrow"
android:background="@drawable/indicator_arrow"
android:layout_height="wrap_content"/>

<ProgressBar android:layout_width="30dp"
android:layout_centerInParent="true"
android:layout_height="30dp"
android:visibility="invisible"
android:id="@+id/pb_rotate"
android:indeterminateDuration="1000"
android:indeterminateDrawable="@drawable/indeterminate_drawable"
/>

</RelativeLayout>

<LinearLayout android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="10dp"
android:layout_marginBottom="10dp"
android:gravity="center"
android:layout_marginLeft="15dp"
android:orientation="vertical">
<TextView android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textSize="20sp"
android:id="@+id/tv_state"
android:textColor="#aa000000"
android:text="下拉刷新"/>
<TextView android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textSize="14sp"
android:id="@+id/tv_time"
android:textColor="@android:color/darker_gray"
android:text="最后刷新："/>

</LinearLayout>

</LinearLayout>

第四步：R.layout.activity_main

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context="com.zd.listviewtest.MainActivity">

<com.zd.listviewtest.RefreshListView
android:id="@+id/refreshListView"
android:layout_height="match_parent"
android:layout_width="match_parent" />

</RelativeLayout>

第五步：自定义一个带下拉刷新，上拉加载的listView

package com.zaizai.dropdownrefresh.view;import java.text.SimpleDateFormat;import java.util.Date;import android.widget.AbsListView.OnScrollListener;import android.content.Context;import android.util.AttributeSet;import android.view.MotionEvent;import android.view.View;import android.view.animation.RotateAnimation;import android.widget.AbsListView;import android.widget.ImageView;import android.widget.ListView;import android.widget.ProgressBar;import android.widget.TextView;import com.zaizai.dropdownrefresh.R;public class RefreshListView extends ListView implements OnScrollListener {private View headerView;//headerViewprivate ImageView ivArrow;private ProgressBar pbRotate;private TextView tvState, tvTime;private View footerView;private int footerViewHeight;private int headerViewHeight;//headerView高private int downY;//按下时y坐标private final int PULL_REFRESH = 0;//下拉刷新的状态private final int RELEASE_REFRESH = 1;//松开刷新的状态private final int REFRESHING = 2;//正在刷新的状态private int currentState = PULL_REFRESH;private RotateAnimation upAnimation, downAnimation;private boolean isLoadingMore = false;//当前是否正在处于加载更多public RefreshListView(Context context) {super(context);init();}public RefreshListView(Context context, AttributeSet attrs) {super(context, attrs);init();}private void init() {//设置滚动监听事件setOnScrollListener(this);initHeaderView();initRotateAnimation();initFooterView();}/*** 初始化headerView*/private void initHeaderView() {headerView = View.inflate(getContext(), R.layout.layout_header, null);ivArrow = (ImageView) headerView.findViewById(R.id.iv_arrow);pbRotate = (ProgressBar) headerView.findViewById(R.id.pb_rotate);tvState = (TextView) headerView.findViewById(R.id.tv_state);tvTime = (TextView) headerView.findViewById(R.id.tv_time);headerView.measure(0, 0);//主动通知系统去测量该view;headerViewHeight = headerView.getMeasuredHeight(); //获得View的高度headerView.setPadding(0, -headerViewHeight, 0, 0);  //将View隐藏，在下拉时在显示//将其放在第一个view位置addHeaderView(headerView);}/*** 初始化旋转动画*/private void initRotateAnimation() {upAnimation = new RotateAnimation(0, -180,RotateAnimation.RELATIVE_TO_SELF, 0.5f,RotateAnimation.RELATIVE_TO_SELF, 0.5f);upAnimation.setDuration(300);upAnimation.setFillAfter(true);downAnimation = new RotateAnimation(-180, -360,RotateAnimation.RELATIVE_TO_SELF, 0.5f,RotateAnimation.RELATIVE_TO_SELF, 0.5f);downAnimation.setDuration(300);downAnimation.setFillAfter(true);}private void initFooterView() {footerView = View.inflate(getContext(), R.layout.layout_footer, null);footerView.measure(0, 0);//主动通知系统去测量该view;footerViewHeight = footerView.getMeasuredHeight(); //获得底部view的高度footerView.setPadding(0, -footerViewHeight, 0, 0);   //将其隐藏addFooterView(footerView);  //设置为最底部的View}@Overridepublic boolean onTouchEvent(MotionEvent ev) {switch (ev.getAction()) {case MotionEvent.ACTION_DOWN: {//获得按下的Y值downY = (int) ev.getY();break;}case MotionEvent.ACTION_MOVE: {if (currentState == REFRESHING) {//正在加载数据未完成，此时拖动不处理break;}//下拉的距离int deltaY = (int) (ev.getY() - downY);int paddingTop = -headerViewHeight + deltaY;//下拉的距离大于0且第一个条目已经出现if (paddingTop > -headerViewHeight && getFirstVisiblePosition() == 0) {/*根据下拉的距离重新定位headerView*/headerView.setPadding(0, paddingTop, 0, 0);//          Log.e("RefreshListView", "paddingTop: "+paddingTop);if (paddingTop >= 0 && currentState == PULL_REFRESH) {//从下拉刷新进入松开刷新状态currentState = RELEASE_REFRESH;//更新headerView状态refreshHeaderView();} else if (paddingTop < 0 && currentState == RELEASE_REFRESH) {//进入下拉刷新状态currentState = PULL_REFRESH;refreshHeaderView();}return true;//拦截TouchMove。不d8ed让listview处理该次move事件,会造成listview无法滑动}break;}case MotionEvent.ACTION_UP: {if (currentState == PULL_REFRESH) {//隐藏headerViewheaderView.setPadding(0, -headerViewHeight, 0, 0);} else if (currentState == RELEASE_REFRESH) {headerView.setPadding(0, 0, 0, 0);currentState = REFRESHING;refreshHeaderView();if (listener != null) {listener.onPullRefresh();}}break;}default: {break;}}return super.onTouchEvent(ev);}/*** 根据currentState来更新headerView状态*/private void refreshHeaderView() {switch (currentState) {case PULL_REFRESH:tvState.setText("下拉刷新");ivArrow.startAnimation(downAnimation);break;case RELEASE_REFRESH:tvState.setText("松开刷新");ivArrow.startAnimation(upAnimation);break;case REFRESHING:ivArrow.clearAnimation();//因为向上的旋转动画有可能没有执行完ivArrow.setVisibility(View.INVISIBLE);pbRotate.setVisibility(View.VISIBLE);tvState.setText("正在刷新...");break;}}/*** 完成刷新操作，重置状态,在你获取完数据并更新完adater之后，去在UI线程中调用该方法*/public void completeRefresh() {if (isLoadingMore) {//重置footerView状态footerView.setPadding(0, -footerViewHeight, 0, 0);isLoadingMore = false;} else {//重置headerView状态headerView.setPadding(0, -headerViewHeight, 0, 0);currentState = PULL_REFRESH;pbRotate.setVisibility(View.INVISIBLE);ivArrow.setVisibility(View.VISIBLE);tvState.setText("下拉刷新");tvTime.setText("最后刷新：" + getCurrentTime());}}/*** 获取当前系统时间，并格式化** @return*/private String getCurrentTime() {SimpleDateFormat format = new SimpleDateFormat("yy-MM-dd HH:mm:ss");return format.format(new Date());}private OnRefreshListener listener;public void setOnRefreshListener(OnRefreshListener listener) {this.listener = listener;}public interface OnRefreshListener {void onPullRefresh();void onLoadingMore();}/*** SCROLL_STATE_IDLE:闲置状态，就是手指松开* SCROLL_STATE_TOUCH_SCROLL：手指触摸滑动，就是按着来滑动* SCROLL_STATE_FLING：快速滑动后松开*/@Overridepublic void onScrollStateChanged(AbsListView view, int scrollState) {if (scrollState == OnScrollListener.SCROLL_STATE_IDLE&& getLastVisiblePosition() == (getCount() - 1) && !isLoadingMore) {isLoadingMore = true;footerView.setPadding(0, 0, 0, 0);//显示出footerViewsetSelection(getCount());//让listview最后一条显示出来if (listener != null) {listener.onLoadingMore();}}}@Overridepublic void onScroll(AbsListView view, int firstVisibleItem,int visibleItemCount, int totalItemCount) {}}

第五步：自定义listView使用

package com.zaizai.dropdownrefresh;import android.os.Handler;import android.os.SystemClock;import android.support.v7.app.AppCompatActivity;import android.os.Bundle;import android.view.View;import android.view.ViewGroup;import android.view.Window;import android.widget.BaseAdapter;import android.widget.TextView;import com.zaizai.dropdownrefresh.view.RefreshListView;import java.util.ArrayList;public class MainActivity extends AppCompatActivity {private RefreshListView refreshListView;private ArrayList<String> list = new ArrayList<String>();private MyAdapter adapter;private Handler handler = new Handler() {public void handleMessage(android.os.Message msg) {//更新UIadapter.notifyDataSetChanged();refreshListView.completeRefresh();};};@Overrideprotected void onCreate(Bundle savedInstanceState) {requestWindowFeature(Window.FEATURE_NO_TITLE);super.onCreate(savedInstanceState);initView();initData();}private void initView() {setContentView(R.layout.activity_main);refreshListView = (RefreshListView) findViewById(R.id.refreshListView);}private void initData() {for (int i = 0; i < 15; i++) {list.add("listview原来的数据 - " + i);}//    final View headerView = View.inflate(this, R.layout.layout_header, null);//第一种方法//    headerView.getViewTreeObserver().addOnGlobalLayoutListener(new OnGlobalLayoutListener() {//       @Override//       public void onGlobalLayout() {//          headerView.getViewTreeObserver().removeGlobalOnLayoutListener(this);//          int headerViewHeight = headerView.getHeight();//////          Log.e("MainActivity", "headerViewHeight: "+headerViewHeight);//          headerView.setPadding(0, -headerViewHeight, 0, 0);//          refreshListView.addHeaderView(headerView);////       }//    });//第二种方法//    headerView.measure(0, 0);//主动通知系统去测量//    int headerViewHeight = headerView.getMeasuredHeight();//    Log.e("MainActivity", "headerViewHeight: "+headerViewHeight);//    headerView.setPadding(0, -headerViewHeight, 0, 0);//    refreshListView.addHeaderView(headerView);//adapter = new MyAdapter();refreshListView.setAdapter(adapter);refreshListView.setOnRefreshListener(new RefreshListView.OnRefreshListener() {@Overridepublic void onPullRefresh() {//需要联网请求服务器的数据，然后更新UIrequestDataFromServer(false);}@Overridepublic void onLoadingMore() {requestDataFromServer(true);}});}/*** 模拟向服务器请求数据*/private void requestDataFromServer(final boolean isLoadingMore) {new Thread() {public void run() {SystemClock.sleep(3000);//模拟请求服务器的一个时间长度if (isLoadingMore) {list.add("加载更多的数据-1");list.add("加载更多的数据-2");list.add("加载更多的数据-3");} else {list.add(0, "下拉刷新的数据");}//在UI线程更新UIhandler.sendEmptyMessage(0);};}.start();}class MyAdapter extends BaseAdapter {@Overridepublic int getCount() {return list.size();}@Overridepublic Object getItem(int position) {return null;}@Overridepublic long getItemId(int position) {return 0;}@Overridepublic View getView(int position, View convertView, ViewGroup parent) {TextView textView = new TextView(MainActivity.this);textView.setPadding(20, 20, 20, 20);textView.setTextSize(18);textView.setText(list.get(position));return textView;}}}

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