Android studio请求网络数据ListView异步加载展示文字条目 ImageLoadler加载图片

最新推荐文章于 2021-05-27 17:12:34 发布

彦4212

最新推荐文章于 2021-05-27 17:12:34 发布

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本文介绍了一个基于Android平台的新闻列表应用实现过程，包括使用ListView展示新闻列表、通过自定义Adapter加载图文内容、利用异步任务进行网络数据请求，并借助Gson解析JSON数据，同时运用Universal Image Loader处理图片加载。

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主函数布局是一个ListView

item布局是TextView和ImageView 数量的多少视情况而定

再写一个网络请求数据的类最后面有代码： ”urlConnection 请求数据类的封装“

类名一定要一样

封装数据类还有别忘了依赖和权限

依赖：

imageloader compile ‘com.nostra13.universalimageloader:universal-image-loader:1.9.5’

gson compile 'com.google.code.gson:gson:2.6.2'

Tablayout compile 'com.android.support:design:26+'

pulltorefresh compile 'com.android.support:support-v4:23.3.0' 或 compile 'com.github.userswlwork:pull-to-refresh:1.0.0'

Banner无限轮播 		compile 'com.youth.banner:banner:1.4.9'

权限：

<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>

主页面 MainActivity
package com.example.myapplication;

import android.graphics.Bitmap;
import android.os.AsyncTask;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.ListView;
import android.widget.TextView;

import com.google.gson.Gson;
import com.nostra13.universalimageloader.core.DisplayImageOptions;
import com.nostra13.universalimageloader.core.ImageLoader;
import com.nostra13.universalimageloader.core.assist.ImageScaleType;

import java.util.List;

public class MainActivity extends AppCompatActivity {

    private ListView lv;
    String urlTotal = "https://api.tianapi.com/wxnew/?key=8d6e3228d25298f13af4fc40ce6c9679&num=10&page=1";
    private MAdapter mAdapter;
    private List<News.NewslistBean> list;
    private String imageUrl="";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        lv = (ListView) findViewById(R.id.lv);
        initData();


    }

    private void initData() {
        new MJsonAsyncTask().execute(urlTotal);
    }

    class MJsonAsyncTask extends AsyncTask<String, Void, String> {
        public MJsonAsyncTask() {
            super();
        }
        //主线程可以更新ui
        @Override
        protected void onPostExecute(String s) {
            super.onPostExecute(s);
            News news = new Gson().fromJson(s, News.class);
            list = news.getNewslist();
            mAdapter = new MAdapter();
            lv.setAdapter(mAdapter);
        }

        //这个回调方法是子线程;
        @Override
        protected String doInBackground(String... strings) {
            //取第0个元素,就是url;
            String netjson = NetWordUtils.getNetjson(strings[0]);//调用网络请求工具类
            return netjson;
        }
    }
    class MAdapter extends BaseAdapter {
        @Override
        public int getCount() {
            return list.size();
        }

        @Override
        public Object getItem(int i) {
            return list.get(i);
        }

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

        @Override
        public View getView(int i, View containerView, ViewGroup viewGroup) {
            View view = View.inflate(MainActivity.this, R.layout.item, null);
            TextView tv_name = (TextView) view.findViewById(R.id.tv);
            ImageView iv = (ImageView) view.findViewById(R.id.iv);
            tv_name.setText(list.get(i).getTitle());
            /**
             * getView方法每个条目显示的时候都会调用,所以我们在这个请求图片,并设置
             *  把图片url传递给asyncTask
             */
            //new MAsyncTaskImage(iv).execute(list.get(i).getPicUrl());
            ImageLoader.getInstance().displayImage(list.get(i).getPicUrl(),iv);
        //    Log.d("wyy",list.get(i).getPicUrl());
            return view;
        }
    }

}

mapp类（清单文件中记得写name=".mapp"）;
package com.example.myapplication;

import android.app.Application;

import com.nostra13.universalimageloader.core.ImageLoader;
import com.nostra13.universalimageloader.core.ImageLoaderConfiguration;

/**
 * Created by DELL- on 2017/11/6.
 */

public class mapp extends Application {
    @Override
    public void onCreate() {
        super.onCreate();
        ImageLoaderConfiguration config = new ImageLoaderConfiguration.Builder(this).build();//开始构建
        ImageLoader.getInstance().init(config);//全局初始化此配置
    }
}
清单文件：

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.myapplication">
    <uses-permission android:name="android.permission.INTERNET" />
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
    <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>
    <application
        android:name=".mapp"
        android:allowBackup="true" android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name" android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true" android:theme="@style/AppTheme">
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

NetWordUtils类（工具类）

package com.example.myapplication;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.util.Log;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
/**
 *  2017-09-27.
 */
public class NetWordUtils {

    private static String  tag = "NetWordUtils";
    /**
     * 获取网络json
     *
     * @param urlString
     * @return
     */
    public static String getNetjson(String urlString) {

        try {
            URL url = new URL(urlString);
            HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
            urlConnection.setRequestMethod("GET");//若果是get请求可以不用配置; 其他请求必须配置
            urlConnection.setConnectTimeout(8000);//设置链接超时间

            InputStream inputStream = urlConnection.getInputStream();//获取网络返回的输入流;
            //可拼接的字符串
            StringBuilder stringBuilder = new StringBuilder();
            BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream));
            String temp = "";
            while ((temp = bufferedReader.readLine()) != null) {
                stringBuilder.append(temp);
                temp = "";
            }
            //这个是网络获取的数据
            String data = stringBuilder.toString();
            Log.e(tag, "getData: " + data);
            return data;
        } catch (MalformedURLException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return "";
    }
}