AsyncTask异步；ListView列表展示数据

AsyncTask异步ListView列表展示数据

libs文件夹下加入jar包（导包）： gson

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添加权限：

网络请求权限：INTERNET
<uses-permission android:name="android.permission.INTERNET"/>
网络判断权限：ACCESS_NETWORK_STATE
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>

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布局：

<ListView    android:id="@+id/list_view"    android:layout_width="match_parent"    android:layout_height="match_parent" />==========================================================================

json解析类：https://api.tianapi.com/wxnew/?key=32b83b189e5e5e520db1612a83d82033&num=10

============================================================主要方法：import android.os.AsyncTask;import android.support.v7.app.AppCompatActivity;import android.os.Bundle;import android.widget.ListView;import com.google.gson.Gson;import java.io.BufferedReader;import java.io.InputStream;import java.io.InputStreamReader;import java.net.HttpURLConnection;import java.net.URL;import java.util.List;public class MainActivity extends AppCompatActivity {    private ListView listview;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        listview = findViewById(R.id.list_view);        MyTask myTask = new MyTask();        myTask.execute("https://api.tianapi.com/wxnew/?key=32b83b189e5e5e520db1612a83d82033&num=10");    }    class MyTask extends AsyncTask<String, Void, String> {        @Override        protected String doInBackground(String... strings) {            StringBuilder builder = new StringBuilder();            try {                URL url = new URL(strings[0]);                HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();                urlConnection.setConnectTimeout(5000);                urlConnection.setReadTimeout(5000);                urlConnection.setRequestMethod("GET");                if (urlConnection.getResponseCode() == 200) {                    InputStream inputStream = urlConnection.getInputStream();                    BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));                    String str;                    while ((str = reader.readLine()) != null) {                        builder.append(str);                    }                }            } catch (Exception e) {                e.printStackTrace();            }            return builder.toString();        }        @Override        protected void onPostExecute(String s) {            super.onPostExecute(s);            Gson gson = new Gson();            Result result = gson.fromJson(s, Result.class);            List<Result.NewslistBean> data = result.getNewslist();            MyAdapter myAdapter = new MyAdapter(data, MainActivity.this);            listview.setAdapter(myAdapter);        }    }}

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MyAdapter 适配器方法：

import android.content.Context;import android.graphics.Bitmap;import android.graphics.BitmapFactory;import android.os.AsyncTask;import android.view.LayoutInflater;import android.view.View;import android.view.ViewGroup;import android.widget.BaseAdapter;import android.widget.ImageView;import android.widget.TextView;import java.io.InputStream;import java.net.HttpURLConnection;import java.net.URL;import java.util.List;class MyAdapter extends BaseAdapter {    private List<Result.NewslistBean> data;    private Context context;    public MyAdapter(List<Result.NewslistBean> data, Context context) {        this.data = data;        this.context = context;    }    @Override    public int getCount() {        return data.size();    }    @Override    public Object getItem(int i) {        return data.get(i);    }    @Override    public long getItemId(int i) {        return i;    }    @Override    public View getView(int i, View view, ViewGroup viewGroup) {        ViewHolder holder;        if (view == null) {            view= LayoutInflater.from(context).inflate(R.layout.item,null);            holder = new ViewHolder();            holder.name=view.findViewById(R.id.name);            holder.img=view.findViewById(R.id.img);            view.setTag(holder);        }else {            holder = (ViewHolder) view.getTag();        }        holder.name.setText(data.get(i).getDescription());        new MyTask(holder.img).execute(data.get(i).getPicUrl());        return view;    }    class ViewHolder {        public TextView name;        public ImageView img;    }    class MyTask extends AsyncTask<String, Void, Bitmap> {        private ImageView img;        public MyTask(ImageView img) {            this.img = img;        }        @Override        protected Bitmap doInBackground(String... strings) {            Bitmap bitmap = null;            try {                URL url = new URL(strings[0]);                HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();                urlConnection.setConnectTimeout(5000);                urlConnection.setReadTimeout(5000);                urlConnection.setRequestMethod("GET");                if (urlConnection.getResponseCode() == 200) {                    InputStream inputStream = urlConnection.getInputStream();                    bitmap = BitmapFactory.decodeStream(inputStream);                }            } catch (Exception e) {                e.printStackTrace();            }            return bitmap;        }        @Override        protected void onPostExecute(Bitmap bitmap) {            super.onPostExecute(bitmap);            img.setImageBitmap(bitmap);        }    }}-------------------------------------------

R.layout.item

<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">    <ImageView        android:id="@+id/img"        android:layout_width="50dp"        android:layout_height="50dp"        android:layout_margin="10dp"        tools:layout_editor_absoluteX="16dp"        tools:layout_editor_absoluteY="16dp" />    <TextView        android:id="@+id/name"        android:layout_width="200dp"        android:layout_height="50dp"        android:layout_alignTop="@+id/img"        android:layout_toEndOf="@+id/img"        android:layout_toRightOf="@+id/img"        tools:layout_editor_absoluteX="80dp"        tools:layout_editor_absoluteY="16dp" /></RelativeLayout>==================================================================

原文地址：https://www.cnblogs.com/shenhuiran/p/8125669.html