Android自定义控件下拉刷新实例代码

实现效果:

图片素材:

--> 首先, 写先下拉刷新时的刷新布局 pull_to_refresh.xml:

<resources>
  <string name="app_name">PullToRefreshTest</string>
  <string name="pull_to_refresh">下拉可以刷新</string>
  <string name="release_to_refresh">释放立即刷新</string>
  <string name="refreshing">正在刷新...</string>
  <string name="not_updated_yet">暂未更新过</string>
  <string name="updated_at">上次更新于%1$s前</string>
  <string name="updated_just_now">刚刚更新</string>
  <string name="time_error">时间有问题</string>
</resources>
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
  android:id="@+id/pull_to_refresh_head"
  android:layout_width="match_parent"
  android:layout_height="60dp">
  <LinearLayout
    android:layout_width="200dp"
    android:layout_height="60dp"
    android:layout_centerInParent="true"
    android:orientation="horizontal">
    <RelativeLayout
      android:layout_width="0dp"
      android:layout_height="60dp"
      android:layout_weight="3">
      <ImageView
        android:id="@+id/arrow"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerInParent="true"
        android:src="@mipmap/indicator_arrow" />
      <ProgressBar
        android:id="@+id/progress_bar"
        android:layout_width="30dp"
        android:layout_height="30dp"
        android:layout_centerInParent="true"
        android:visibility="gone" />
    </RelativeLayout>
    <LinearLayout
      android:layout_width="0dp"
      android:layout_height="60dp"
      android:layout_weight="12"
      android:orientation="vertical">
      <TextView
        android:id="@+id/description"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1"
        android:gravity="center_horizontal|bottom"
        android:text="@string/pull_to_refresh" />
      <TextView
        android:id="@+id/updated_at"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1"
        android:gravity="center_horizontal|top"
        android:text="@string/updated_at" />
    </LinearLayout>
  </LinearLayout>
</RelativeLayout>

strings
pull_to_refresh
--> 然后, 也是主要的, 自定义下拉刷新的 View (包含下拉刷新所有操作) RefreshView.java:
package com.dragon.android.tofreshlayout;
import android.content.Context;
import android.content.SharedPreferences;
import android.os.AsyncTask;
import android.os.SystemClock;
import android.preference.PreferenceManager;
import android.util.AttributeSet;
import android.view.LayoutInflater;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewConfiguration;
import android.view.animation.RotateAnimation;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.ListView;
import android.widget.ProgressBar;
import android.widget.TextView;
public class RefreshView extends LinearLayout implements View.OnTouchListener {
private static final String TAG = RefreshView.class.getSimpleName();
public enum PULL_STATUS {
STATUS_PULL_TO_REFRESH(0), // 下拉状态
STATUS_RELEASE_TO_REFRESH(1), // 释放立即刷新状态
STATUS_REFRESHING(2), // 正在刷新状态
STATUS_REFRESH_FINISHED(3); // 刷新完成或未刷新状态
private int status; // 状态
PULL_STATUS(int value) {
this.status = value;
}
public int getValue() {
return this.status;
}
}
// 下拉头部回滚的速度
public static final int SCROLL_SPEED = -20;
// 一分钟的毫秒值，用于判断上次的更新时间
public static final long ONE_MINUTE = 60 * 1000;
// 一小时的毫秒值，用于判断上次的更新时间
public static final long ONE_HOUR = 60 * ONE_MINUTE;
// 一天的毫秒值，用于判断上次的更新时间
public static final long ONE_DAY = 24 * ONE_HOUR;
// 一月的毫秒值，用于判断上次的更新时间
public static final long ONE_MONTH = 30 * ONE_DAY;
// 一年的毫秒值，用于判断上次的更新时间
public static final long ONE_YEAR = 12 * ONE_MONTH;
// 上次更新时间的字符串常量，用于作为 SharedPreferences 的键值
private static final String UPDATED_AT = "updated_at";
// 下拉刷新的回调接口
private PullToRefreshListener mListener;
private SharedPreferences preferences; // 用于存储上次更新时间
private View header; // 下拉头的View
private ListView listView; // 需要去下拉刷新的ListView
private ProgressBar progressBar; // 刷新时显示的进度条
private ImageView arrow; // 指示下拉和释放的箭头
private TextView description; // 指示下拉和释放的文字描述
private TextView updateAt; // 上次更新时间的文字描述
private MarginLayoutParams headerLayoutParams; // 下拉头的布局参数
private long lastUpdateTime; // 上次更新时间的毫秒值
// 为了防止不同界面的下拉刷新在上次更新时间上互相有冲突，使用id来做区分
private int mId = -1;
private int hideHeaderHeight; // 下拉头的高度

private PULL_STATUS currentStatus = PULL_STATUS.STATUS_REFRESH_FINISHED;
// 记录上一次的状态是什么，避免进行重复操作
private PULL_STATUS lastStatus = currentStatus;
private float yDown; // 手指按下时的屏幕纵坐标
private int touchSlop; // 在被判定为滚动之前用户手指可以移动的最大值。
private boolean loadOnce; // 是否已加载过一次layout，这里onLayout中的初始化只需加载一次
private boolean ableToPull; // 当前是否可以下拉，只有ListView滚动到头的时候才允许下拉

public RefreshView(Context context, AttributeSet attrs) {
super(context, attrs);
preferences = PreferenceManager.getDefaultSharedPreferences(context);
header = LayoutInflater.from(context).inflate(R.layout.pull_to_refresh, null, true);
progressBar = (ProgressBar) header.findViewById(R.id.progress_bar);
arrow = (ImageView) header.findViewById(R.id.arrow);
description = (TextView) header.findViewById(R.id.description);
updateAt = (TextView) header.findViewById(R.id.updated_at);
touchSlop = ViewConfiguration.get(context).getScaledTouchSlop();
refreshUpdatedAtValue();
setOrientation(VERTICAL);
addView(header, 0);
//Log.d(TAG, "RefreshView Constructor() getChildAt(0): " + getChildAt(0));
//Log.d(TAG, "RefreshView Constructor() getChildAt(0): " + getChildAt(1));
// listView = (ListView) getChildAt(1);
// listView.setOnTouchListener(this);
}

@Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
super.onLayout(changed, l, t, r, b);
if (changed && !loadOnce) {
hideHeaderHeight = -header.getHeight();
headerLayoutParams = (MarginLayoutParams) header.getLayoutParams();
headerLayoutParams.topMargin = hideHeaderHeight;
listView = (ListView) getChildAt(1);
//Log.d(TAG, "onLayout() getChildAt(0): " + getChildAt(0));
//Log.d(TAG, "onLayout() listView: " + listView);
listView.setOnTouchListener(this);
loadOnce = true;
}
}

@Override
public boolean onTouch(View v, MotionEvent event) {
setCanAbleToPull(event); // 判断是否可以下拉
if (ableToPull) {
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
yDown = event.getRawY();
break;
case MotionEvent.ACTION_MOVE:
// 获取移动中的 Y 轴的位置
float yMove = event.getRawY();
// 获取从按下到移动过程中移动的距离
int distance = (int) (yMove - yDown);
// 如果手指是上滑状态，并且下拉头是完全隐藏的，就屏蔽下拉事件
if (distance <= 0 && headerLayoutParams.topMargin <= hideHeaderHeight) {
return false;
}
if (distance < touchSlop) {
return false;
}
// 判断是否已经在刷新状态
if (currentStatus != PULL_STATUS.STATUS_REFRESHING) {
// 判断设置的 topMargin 是否 > 0, 默认初始设置为 -header.getHeight()
if (headerLayoutParams.topMargin > 0) {
currentStatus = PULL_STATUS.STATUS_RELEASE_TO_REFRESH;
} else {
// 否则状态为下拉中的状态
currentStatus = PULL_STATUS.STATUS_PULL_TO_REFRESH;
}
// 通过偏移下拉头的 topMargin 值，来实现下拉效果
headerLayoutParams.topMargin = (distance / 2) + hideHeaderHeight;
header.setLayoutParams(headerLayoutParams);
}
break;
case MotionEvent.ACTION_UP:
default:
if (currentStatus == PULL_STATUS.STATUS_RELEASE_TO_REFRESH) {
// 松手时如果是释放立即刷新状态，就去调用正在刷新的任务
new RefreshingTask().execute();
} else if (currentStatus == PULL_STATUS.STATUS_PULL_TO_REFRESH) {
// 松手时如果是下拉状态，就去调用隐藏下拉头的任务
new HideHeaderTask().execute();
}
break;
}
// 时刻记得更新下拉头中的信息
if (currentStatus == PULL_STATUS.STATUS_PULL_TO_REFRESH
|| currentStatus == PULL_STATUS.STATUS_RELEASE_TO_REFRESH) {
updateHeaderView();
// 当前正处于下拉或释放状态，要让 ListView 失去焦点，否则被点击的那一项会一直处于选中状态
listView.setPressed(false);
listView.setFocusable(false);
listView.setFocusableInTouchMode(false);
lastStatus = currentStatus;
// 当前正处于下拉或释放状态，通过返回 true 屏蔽掉 ListView 的滚动事件
return true;
}
}
return false;
}

public void setOnRefreshListener(PullToRefreshListener listener, int id) {
mListener = listener;
mId = id;
}

public void finishRefreshing() {
currentStatus = PULL_STATUS.STATUS_REFRESH_FINISHED;
preferences.edit().putLong(UPDATED_AT + mId, System.currentTimeMillis()).commit();
new HideHeaderTask().execute();
}

private void setCanAbleToPull(MotionEvent event) {
View firstChild = listView.getChildAt(0);
if (firstChild != null) {
// 获取 ListView 中第一个Item的位置
int firstVisiblePos = listView.getFirstVisiblePosition();
// 判断第一个子控件的 Top 是否和第一个 Item 位置相等
if (firstVisiblePos == 0 && firstChild.getTop() == 0) {
if (!ableToPull) {
// getRawY() 获得的是相对屏幕 Y 方向的位置
yDown = event.getRawY();
}
// 如果首个元素的上边缘，距离父布局值为 0，就说明 ListView 滚动到了最顶部，此时应该允许下拉刷新
ableToPull = true;
} else {
if (headerLayoutParams.topMargin != hideHeaderHeight) {
headerLayoutParams.topMargin = hideHeaderHeight;
header.setLayoutParams(headerLayoutParams);
}
ableToPull = false;
}
} else {
// 如果 ListView 中没有元素，也应该允许下拉刷新
ableToPull = true;
}
}

private void updateHeaderView() {
if (lastStatus != currentStatus) {
if (currentStatus == PULL_STATUS.STATUS_PULL_TO_REFRESH) {
description.setText(getResources().getString(R.string.pull_to_refresh));
arrow.setVisibility(View.VISIBLE);
progressBar.setVisibility(View.GONE);
rotateArrow();
} else if (currentStatus == PULL_STATUS.STATUS_RELEASE_TO_REFRESH) {
description.setText(getResources().getString(R.string.release_to_refresh));
arrow.setVisibility(View.VISIBLE);
progressBar.setVisibility(View.GONE);
rotateArrow();
} else if (currentStatus == PULL_STATUS.STATUS_REFRESHING) {
description.setText(getResources().getString(R.string.refreshing));
progressBar.setVisibility(View.VISIBLE);
arrow.clearAnimation();
arrow.setVisibility(View.GONE);
}
refreshUpdatedAtValue();
}
}

private void rotateArrow() {
float pivotX = arrow.getWidth() / 2f;
float pivotY = arrow.getHeight() / 2f;
float fromDegrees = 0f;
float toDegrees = 0f;
if (currentStatus == PULL_STATUS.STATUS_PULL_TO_REFRESH) {
fromDegrees = 180f;
toDegrees = 360f;
} else if (currentStatus == PULL_STATUS.STATUS_RELEASE_TO_REFRESH) {
fromDegrees = 0f;
toDegrees = 180f;
}
RotateAnimation animation = new RotateAnimation(fromDegrees, toDegrees, pivotX, pivotY);
animation.setDuration(100);
animation.setFillAfter(true);
arrow.startAnimation(animation);
}

private void refreshUpdatedAtValue() {
lastUpdateTime = preferences.getLong(UPDATED_AT + mId, -1);
long currentTime = System.currentTimeMillis();
long timePassed = currentTime - lastUpdateTime;
long timeIntoFormat;
String updateAtValue;
if (lastUpdateTime == -1) {
updateAtValue = getResources().getString(R.string.not_updated_yet);
} else if (timePassed < 0) {
updateAtValue = getResources().getString(R.string.time_error);
} else if (timePassed < ONE_MINUTE) {
updateAtValue = getResources().getString(R.string.updated_just_now);
} else if (timePassed < ONE_HOUR) {
timeIntoFormat = timePassed / ONE_MINUTE;
String value = timeIntoFormat + "分钟";
updateAtValue = String.format(getResources().getString(R.string.updated_at), value);
} else if (timePassed < ONE_DAY) {
timeIntoFormat = timePassed / ONE_HOUR;
String value = timeIntoFormat + "小时";
updateAtValue = String.format(getResources().getString(R.string.updated_at), value);
} else if (timePassed < ONE_MONTH) {
timeIntoFormat = timePassed / ONE_DAY;
String value = timeIntoFormat + "天";
updateAtValue = String.format(getResources().getString(R.string.updated_at), value);
} else if (timePassed < ONE_YEAR) {
timeIntoFormat = timePassed / ONE_MONTH;
String value = timeIntoFormat + "个月";
updateAtValue = String.format(getResources().getString(R.string.updated_at), value);
} else {
timeIntoFormat = timePassed / ONE_YEAR;
String value = timeIntoFormat + "年";
updateAtValue = String.format(getResources().getString(R.string.updated_at), value);
}
updateAt.setText(updateAtValue);
}

class RefreshingTask extends AsyncTask<Void, Integer, Void> {
@Override
protected Void doInBackground(Void... params) {
int topMargin = headerLayoutParams.topMargin;
while (true) {
topMargin = topMargin + SCROLL_SPEED;
if (topMargin <= 0) {
topMargin = 0;
break;
}
publishProgress(topMargin);
SystemClock.sleep(10);
}
currentStatus = PULL_STATUS.STATUS_REFRESHING;
publishProgress(0);
if (mListener != null) {
mListener.onRefresh();
}
return null;
}
@Override
protected void onProgressUpdate(Integer... topMargin) {
updateHeaderView();
headerLayoutParams.topMargin = topMargin[0];
header.setLayoutParams(headerLayoutParams);
}
}

class HideHeaderTask extends AsyncTask<Void, Integer, Integer> {
@Override
protected Integer doInBackground(Void... params) {
int topMargin = headerLayoutParams.topMargin;
while (true) {
topMargin = topMargin + SCROLL_SPEED;
if (topMargin <= hideHeaderHeight) {
topMargin = hideHeaderHeight;
break;
}
publishProgress(topMargin);
SystemClock.sleep(10);
}
return topMargin;
}
@Override
protected void onProgressUpdate(Integer ... topMargin) {
headerLayoutParams.topMargin = topMargin[0];
header.setLayoutParams(headerLayoutParams);
}
@Override
protected void onPostExecute(Integer topMargin) {
headerLayoutParams.topMargin = topMargin;
header.setLayoutParams(headerLayoutParams);
currentStatus = PULL_STATUS.STATUS_REFRESH_FINISHED;
}
}

public interface PullToRefreshListener {
// 刷新时会去回调此方法，在方法内编写具体的刷新逻辑。注意此方法是在子线程中调用的， 可以不必另开线程来进行耗时操作
void onRefresh();
}
}

--> 第三步, 写主布局:

<?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"
  tools:context=".MainActivity" >
  <com.dragon.android.tofreshlayout.RefreshView
    android:id="@+id/refreshable_view"
    android:layout_width="match_parent"
    android:layout_height="match_parent" >
    <ListView
      android:id="@+id/list_view"
      android:layout_width="match_parent"
      android:layout_height="match_parent" >
    </ListView>
  </com.dragon.android.tofreshlayout.RefreshView>
</RelativeLayout>

--> 最后, Java 代码添加 ListView 的数据:

package com.dragon.android.tofreshlayout;
import android.os.Bundle;
import android.os.SystemClock;
import android.support.v7.app.AppCompatActivity;
import android.webkit.WebView;
import android.widget.ArrayAdapter;
import android.widget.ListView;
public class MainActivity extends AppCompatActivity {
  RefreshView refreshableView;
  ListView listView;
  ArrayAdapter<String> adapter;
  private WebView webView;
  private static int NUM = 30;
  String[] items = new String[NUM];
  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    getSupportActionBar().hide();
    for (int i = 0; i < items.length; i++) {
      items[i] = "列表项" + i;
    }
    refreshableView = (RefreshView) findViewById(R.id.refreshable_view);
    listView = (ListView) findViewById(R.id.list_view);
    adapter = new ArrayAdapter<>(this, android.R.layout.simple_list_item_1, items);
    listView.setAdapter(adapter);
    refreshableView.setOnRefreshListener(new RefreshView.PullToRefreshListener() {
      @Override
      public void onRefresh() {
        SystemClock.sleep(3000);
        refreshableView.finishRefreshing();
      }
    }, 0);
  }
}

程序 Demo: 链接：http://pan.baidu.com/s/1ge6Llw3 密码：skna

***************其实还应该再封装的...*****************

以上所述是小编给大家介绍的Android自定义控件下拉刷新实例代码，希望对大家有所帮助，如果大家有任何疑问请给我留言，小编会及时回复大家的。在此也非常感谢大家对编程网网站的支持！

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