实现XlistView的简洁方法PullToRefreshListView

来源：互联网发布：u盘做linux启动盘编辑：程序博客网时间：2024/06/06 02:56

XListView是一个含有下拉刷新、上拉加载功能的控件。特点是代码量极少（只有3个java文件和2个xml文件即可实现），虽然功能较为单一，但是在项目开发中很实用。并且由于代码量小，可以很轻松的理解下拉刷新和下拉加载的源码机制，并加以自定制。

下拉刷新这个功能我们都比较常见了，下面我要介绍的就是这个功能的实现。下面就是我们比较常见的PullToRefreshListView，是让listView有下拉刷新功能。

首先他的

下载项目包，将library包导入即可，其他的包暂时不用

主视图

<?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:id="@+id/activity_main"
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.bwie.myapplication123.MainActivity">
>

<com.handmark.pulltorefresh.library.PullToRefreshListView
xmlns:ptr="http://schemas.android.com/apk/res-auto"
android:id="@+id/pull_refresh_list"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:cacheColorHint="#000000"
android:divider="#19000000"
android:dividerHeight="4dp"
android:fadingEdge="none"
android:fastScrollEnabled="false"
android:footerDividersEnabled="false"
android:headerDividersEnabled="false"
android:smoothScrollbar="true"
ptr:ptrAnimationStyle="rotate"
ptr:ptrHeaderTextColor="#ffffff"
ptr:ptrHeaderSubTextColor="#00ffff"
ptr:ptrHeaderBackground="@null"
ptr:ptrDrawable="@mipmap/ic_launcher"/>
</RelativeLayout>

<?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">

<TextView
android:text="TextView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/newsname"
android:layout_weight="1" />
<TextView
android:text="TextView"
android:layout_marginLeft="10dp"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/newstime"
android:layout_weight="1" />
</LinearLayout>

开始编写代码

1.找到这个控件，并且设置监听器

这里面用到了一个日期的工具类，其实就是设置上次下拉的时间的。此外在下拉后会触发一个异步任务

package com.bwie.myapplication;

import android.os.AsyncTask;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.widget.ListView;
import android.widget.Toast;

import com.google.gson.Gson;
import com.handmark.pulltorefresh.library.PullToRefreshBase;
import com.handmark.pulltorefresh.library.PullToRefreshListView;

import java.util.ArrayList;
import java.util.List;

public class MainActivity extends AppCompatActivity {

private PullToRefreshListView listView;
private static final String JSON_URL = "http://www.93.gov.cn/93app/data.do?channelId=2&startNum=";
private ArrayList<News> newsList;
private MyBaseAdapter myAdatper;
private List<News.DataBean> data;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//初始化组件
initView();
//初始化加载数据
initData();
}

public void initData(){
pullToRefreshData();
}
//下载刷新，加载数据，显示数据
public void pullToRefreshData(){
new AsyncTask<String,Integer,String>(){
@Override
protected String doInBackground(String... params) {

String json = new NetWorkUtil().getJsonByHttpUrlConnection(JSON_URL+"1");

return json;
}

@Override
protected void onPostExecute(String s) {
super.onPostExecute(s);
//解析json
Gson gson =new Gson();
News news = gson.fromJson(s, News.class);
data = news.getData();

myAdatper = new MyBaseAdapter(MainActivity.this, data);
listView.setAdapter(myAdatper);

listView.onRefreshComplete();//停止刷新
}
}.execute();
}

int index = 1;
//下载刷新，加载数据，显示数据
public void loadMoreData(){
new AsyncTask<String,Integer,String>(){
@Override
protected String doInBackground(String... params) {
index++;
String json = new NetWorkUtil().getJsonByHttpUrlConnection(JSON_URL+index);
return json;
}

@Override
protected void onPostExecute(String s) {
super.onPostExecute(s);
//解析json
/* SuperClass superClass = new Gson().fromJson(s, SuperClass.class);
newsList.addAll(superClass.getData());*/
Gson gson =new Gson();
News news = gson.fromJson(s, News.class);
data.addAll(news.getData());
myAdatper.notifyDataSetChanged();
}
}.execute();
}

public void initView(){
listView = (PullToRefreshListView) findViewById(R.id.pull_refresh_list);
listView.setOnRefreshListener(new PullToRefreshBase.OnRefreshListener<ListView>() {
@Override
public void onRefresh(PullToRefreshBase<ListView> refreshView) {
//当下拉刷新，进入此方法
Toast.makeText(MainActivity.this,"下拉刷新",Toast.LENGTH_SHORT).show();
//加载新数据，刷新显示
pullToRefreshData();

}
});
listView.setOnLastItemVisibleListener(new PullToRefreshBase.OnLastItemVisibleListener() {
@Override
public void onLastItemVisible() {
Toast.makeText(MainActivity.this,"上拉显示出listview的最后一行",Toast.LENGTH_SHORT).show();
loadMoreData();
}
});
}
}

//一个工具类

package com.bwie.myapplication123;

import android.util.Log;

import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;

/**
* Created by Administrator on 2017/9/15.
*/

public class NetWorkUtil {
public String getJsonByHttpUrlConnection(String jsonUrl){
URL url = null;
HttpURLConnection httpURLConnection = null;
String jsonStr = "";
try {
url = new URL(jsonUrl);//创建URL对象，连接JSON_URL对应的服务器
httpURLConnection = (HttpURLConnection) url.openConnection();//打开连接
httpURLConnection.setConnectTimeout(5000);//设置请求时长为5秒
httpURLConnection.setReadTimeout(5000);//设置读取服务器响应数据的时长

int resCode = httpURLConnection.getResponseCode();//得到响应结果码

if(resCode == 200){//表示响应成功，可以获得相应的额结果
//得到响应的结果,,服务器响应的输入流
InputStream inputStream = httpURLConnection.getInputStream();
byte[] buffers = new byte[1024];
int length = 0;
while((length = inputStream.read(buffers)) != -1){//本次循环成立，说明读取到了数据
jsonStr += new String(buffers,0,length);
}
//循环完毕，读取数据完毕
Log.d("main",jsonStr);
}
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return jsonStr;
}
}

在这里Ben我就不传了
接下来还有一个适配器
package com.bwie.myapplication123;

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

import java.util.List;

public class MyBaseAdapter extends BaseAdapter {
private Context context;
private List<News.DataBean> newsList;

public MyBaseAdapter(Context context, List<News.DataBean> newsList) {
this.context = context;
this.newsList = newsList;
}

@Override
public int getCount() {
return newsList.size();
}

@Override
public Object getItem(int position) {
return null;
}

@Override
public long getItemId(int position) {
return 0;
}

@Override
public View getView(int position, View convertView, ViewGroup parent) {
ViewHolder viewHolder = null;
if(convertView == null){
viewHolder = new ViewHolder();
convertView = View.inflate(context, R.layout.list_item, null);
viewHolder.newsName = (TextView) convertView.findViewById(R.id.newsname);
viewHolder.newsTime = (TextView) convertView.findViewById(R.id.newstime);

convertView.setTag(viewHolder);
}else{
viewHolder = (ViewHolder) convertView.getTag();
}

//配置数据
News.DataBean dataBean = newsList.get(position);

viewHolder.newsName.setText(dataBean.getTITLE().substring(0,5));
viewHolder.newsTime.setText(dataBean.getSHOWTIME());
return convertView;
}

class ViewHolder{
TextView newsName,newsTime;
}
}

别忘了加权限<uses-permission android:name="android.permission.INTERNET"/>

阅读全文

1 0