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android 上拉加载

分类: IT文章 • 2022-04-29 19:38:35
场景：Android 下拉刷新上拉加载成效功能

Android 下拉刷新上拉加载效果功能

应用场景：

在App开发中，对于信息的获取与演示，不可能全部将其获取与演示，为了在用户使用中，给予用户以友好、方便的用户体验，以滑动、下拉的效果动态加载数据的要求就会出现。为此，该效果功能就需要应用到所需要的展示页面中。

知识点介绍：

本文主要根据开源项目android-pulltorefresh展开介绍。
android-pulltorefresh 
【一个强大的拉动刷新开源项目，支持各种控件下拉刷新 ListView、ViewPager、WevView、ExpandableListView、GridView、(Horizontal )ScrollView、Fragment上下左右拉动刷新，比下面johannilsson那个只支持ListView的强大的多。并且他实现的下拉刷新ListView在item不足一屏情况下也不会显示刷新提示，体验更好。】 
项目地址：
https://github.com/chrisbanes/Android-PullToRefresh 
Demo地址：
https://github.com/Trinea/TrineaDownload/blob/master/pull-to-refreshview-demo.apk?raw=true 

使用方式：

第一步：新建Android工程SampleDemo
第二步：在res/values下新建attrs.xml
<?xml version="1.0" encoding="utf-8"?>
<resources>
    <declare-styleable name="PullToRefresh">
        <attr name="mode" format="reference" >
            <flag name="pullDownFromTop" value="0x1" />
            <flag name="pullUpFromBottom" value="0x2" />
            <flag name="both" value="0x3" />
        </attr>
    </declare-styleable>
</resources>
srings.xml
<?xml version="1.0" encoding="utf-8"?>
<resources>
    <string name="app_name">SampleDemo</string>
    <string name="action_settings">Settings</string>
    <string name="pull_to_refresh_pull_down_label">滑动刷新</string>
    <string name="pull_to_refresh_release_label">释放刷新</string>
    <string name="pull_to_refresh_refreshing_label">加载中</string>
    <string name="pull_to_refresh_tap_label">点击刷新</string>
</resources>
第三步：将所需要的图片文件放入相应的文件夹下面，所用的图片文件有：
android 上拉加载
第四步：
1、导入或将开源项目android-pulltorefresh中需要的类文件(.java)，加入到自己的项目中的指定包内。
该演示用例涉及的类文件为：
【library\src\com\handmark\pulltorefresh\library】
PullToRefreshAdapterViewBase.java
PullToRefreshBase.java
PullToRefreshListView.java
【library\src\com\handmark\pulltorefresh\library\internal】
EmptyViewMethodAccessor.java
LoadingLayout.java
2、构建自己所需要的类文件(.java)。
【PullTask.java】
import java.util.LinkedList;

import com.example.sampledemo.view.PullToRefreshListView;

import android.os.AsyncTask;
import android.widget.BaseAdapter;

public class PullTask extends AsyncTask<Void, Void, String>{

	private PullToRefreshListView pullToRefreshListView;  //实现下拉刷新与上拉加载的ListView
	private int pullState;               //记录判断，上拉与下拉动作
	private BaseAdapter baseAdapter;     //ListView适配器，用于提醒ListView数据已经更新
	private LinkedList<String> linkedList;
	
	public PullTask(PullToRefreshListView pullToRefreshListView, int pullState,
			BaseAdapter baseAdapter, LinkedList<String> linkedList) {
		this.pullToRefreshListView = pullToRefreshListView;
		this.pullState = pullState;
		this.baseAdapter = baseAdapter;
		this.linkedList = linkedList;
	}
	
	@Override
	protected String doInBackground(Void... params) {
		try {
			Thread.sleep(1000);
		} catch (InterruptedException e) {
		}
		return "StringTest";
	}

	@Override
	protected void onPostExecute(String result) {
		if(pullState == 1) {//name="pullDownFromTop" value="0x1" 下拉
			linkedList.addFirst("顶部数据");
		}
		if(pullState == 2) {//name="pullUpFromBottom" value="0x2" 上拉
			linkedList.addLast("底部数据");
		}
		baseAdapter.notifyDataSetChanged();
		pullToRefreshListView.onRefreshComplete();
		super.onPostExecute(result);
	}
}

【PullAdapter.java】
import java.util.LinkedList;

import com.example.sampledemo.R;

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.TextView;

public class PullAdapter extends BaseAdapter {

	private LinkedList<String> linkedList;
	private LayoutInflater mInflater;
	
	public PullAdapter(LinkedList<String> linkedList, Context context) {
		mInflater = LayoutInflater.from(context);
		this.linkedList = linkedList;
	}
	
	@Override
	public int getCount() {
		return linkedList.size();
	}

	@Override
	public Object getItem(int position) {
		return linkedList.get(position);
	}

	@Override
	public long getItemId(int position) {
		return position;
	}

	@Override
	public View getView(int position, View convertView, ViewGroup parent) {
		ViewHolder holder=null;

		if (convertView == null) {
			holder = new ViewHolder();
			convertView = mInflater.inflate(R.layout.layout_main_listitem, null);
			holder.textView = (TextView) convertView.findViewById(R.id.textView);
			convertView.setTag(holder);
		}else {
			holder = (ViewHolder) convertView.getTag();
		}
		if(linkedList.size()>0){
			final String dataStr = linkedList.get(position);
			holder.textView.setText(dataStr);
		}
		return convertView;
	}

	private static class ViewHolder {
		TextView textView;        //数据显示区域
	}
}

第四步：为PullAdapter.java 设计布局文件layout_main_listitem.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="match_parent"
    android:background="#FFFFFF"
    android:orientation="vertical" >
    <TextView
        android:id="@+id/textView"
        android:textColor="#99CC66"
        android:textSize="18dp"
        android:layout_marginTop="4dp"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="left" />
</LinearLayout>

滑动时出现提醒布局文件pull_to_refresh_header.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:paddingTop="10dp"
    android:paddingBottom="10dip">
     <TextView
        android:id="@+id/pull_to_refresh_text"
        android:text="@string/pull_to_refresh_pull_down_label"
        android:textAppearance="?android:attr/textAppearanceMedium"
        android:textStyle="bold"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerInParent="true" />
    <ProgressBar
        android:id="@+id/pull_to_refresh_progress"
        android:indeterminate="true"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginLeft="30dip"
        android:layout_marginRight="20dip"
        android:visibility="gone"
        android:layout_centerVertical="true"
        style="?android:attr/progressBarStyleSmall" /> 
    <ImageView
        android:id="@+id/pull_to_refresh_image"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginLeft="30dip"
        android:layout_marginRight="20dip"
        android:layout_centerVertical="true" />
</RelativeLayout>

MainActivity.java 主布局文件activity_main.xml
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
 xmlns:cp="http://schemas.android.com/apk/res/com.example.sampledemo"
    android:layout_width="match_parent"
    android:background="#FFFFFF"
    android:layout_height="match_parent">
	<com.example.sampledemo.view.PullToRefreshListView
	    android:id="@+id/pullrefresh"
	    android:background="#FFFFFF"
         android:layout_width="fill_parent"
         android:layout_height="fill_parent"
         android:divider="@android:color/black"
    		android:dividerHeight="0.1dip"
    		android:cacheColorHint="#00000000" 
		cp:mode="both">
	</com.example.sampledemo.view.PullToRefreshListView>
</RelativeLayout>

第五步：编写MainActivity.java 
import java.util.Arrays;
import java.util.LinkedList;

import com.example.sampledemo.view.PullToRefreshBase.OnRefreshListener;
import com.example.sampledemo.view.PullToRefreshListView;
import com.example.sampledemo.view.adapter.PullAdapter;
import com.example.sampledemo.view.task.PullTask;

import android.os.Bundle;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.app.Activity;
/**
 * @ClassName MainActivity.java
 * @Author MaHaochen
 * @Date 2014-4-30 15:56:47
 */
public class MainActivity extends Activity {
	private LinkedList<String> mListItems;
	private PullToRefreshListView mPullRefreshListView;
	private ArrayAdapter<String> mAdapter;
	private ListView mListView;
	private PullAdapter pullAdapter;
	private String[] mStrings = { "初始数据01","初始数据02","初始数据03","初始数据04","初始数据05" 

};
	
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		initViews();
	}

	private void initViews() {
		mPullRefreshListView = (PullToRefreshListView) findViewById(R.id.pullrefresh);
		mPullRefreshListView.setOnRefreshListener(mOnrefreshListener);
		mListView = mPullRefreshListView.getRefreshableView();
		mListItems = new LinkedList<String>();
		mListItems.addAll(Arrays.asList(mStrings));
		pullAdapter = new PullAdapter(mListItems, MainActivity.this);
		mListView.setAdapter(pullAdapter);
	}
	
	OnRefreshListener mOnrefreshListener = new OnRefreshListener() {
		public void onRefresh() {
		PullTask pullTask =	new PullTask(mPullRefreshListView, 

mPullRefreshListView.getRefreshType(), pullAdapter, mListItems);
		pullTask.execute();
		}
	};
}

下载地址：

http://download.csdn.net/detail/ma_hoking/7276365

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