实时加载最新新闻列表（可展示网络图片）

一、设计思路

1、数据源：新闻api：https://www.jianshu.com/p/c54e25349b77。

2、网络请求：封装一个网络请求工具（使用HttpURLConnection）发送URL，返回数据string。

3、数据获取：使用 AsyncTask 异步加载网络数据，及调用工具类的工具函数。

4、数据解析：根据返回的数据和需要的数据，处理从网上获取的字符串，并使用Gson工具将处理后的字符串转换为我们熟悉的java对象。　

5、网络图片展示：自定义一个imageView，用于展示网络图片。（我的是：传入一个网络图片的网址->展示该网络图片）

6、数据展示：使用RecycleView展示列表数据（包括新闻图片、标题、概要、时间）。

7、分析可知需添加依赖：

dependencies {

    implementation 'androidx.recyclerview:recyclerview:1.1.0'
    implementation 'com.google.code.gson:gson:2.8.6'

}

二、效果

三、源代码

1、用于发送网络请求的工具类：

package com.me.androidstudy2.utils;

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;

public class HttpUtil {
    /**
     * 返回json
     * @param setUrl
     * @return
     */
    public static String setUrl(String setUrl){
        try {
            URL url = new URL(setUrl);
            HttpURLConnection conn = (HttpURLConnection)url.openConnection();
            conn.setConnectTimeout(5000);
            conn.setRequestMethod("GET");
            int responseCode = conn.getResponseCode();
            if (responseCode == HttpURLConnection.HTTP_OK){
                InputStream inputStream = conn.getInputStream();
                InputStreamReader inputStreamReader = new InputStreamReader(inputStream);
                BufferedReader reader = new BufferedReader(inputStreamReader);
                StringBuffer stringBuffer = new StringBuffer();
                String string = reader.readLine();
                while (string != null) {
                    stringBuffer.append(string);
                    string = reader.readLine();
                }
                Log.e("web",stringBuffer.toString());
                return stringBuffer.toString();
            }else{
                Log.e("web",responseCode+"");
            }
        } catch (MalformedURLException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return "";
    }
}

2、自定义一个imageView，用于展示网络图片。

package com.me.androidstudy2.view;

import android.annotation.SuppressLint;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Handler;
import android.os.Message;
import android.util.AttributeSet;
import android.widget.ImageView;
import android.widget.Toast;

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

/**
 * 使用时只需调用setImageURL(图片网址);即可
 */
@SuppressLint("AppCompatCustomView")
public class MyImageView extends ImageView {
    public static final int GET_DATA_SUCCESS = 1;
    public static final int NETWORK_ERROR = 2;
    public static final int SERVER_ERROR = 3;
    //子线程不能操作UI，通过Handler设置图片
    private Handler handler = new Handler() {
        @Override
        public void handleMessage(Message msg) {
            switch (msg.what){
                case GET_DATA_SUCCESS:
                    Bitmap bitmap = (Bitmap) msg.obj;
                    setImageBitmap(bitmap);
                    break;
                case NETWORK_ERROR:
                    Toast.makeText(getContext(),"网络连接失败",Toast.LENGTH_SHORT).show();
                    break;
                case SERVER_ERROR:
                    Toast.makeText(getContext(),"服务器发生错误",Toast.LENGTH_SHORT).show();
                    break;
            }
        }
    };

    public MyImageView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    }

    public MyImageView(Context context) {
        super(context);
    }

    public MyImageView(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    //设置网络图片
    public void setImageURL(final String path) {
        //开启一个线程用于联网
        new Thread() {
            @Override
            public void run() {
                try {
                    //把传过来的路径转成URL
                    URL url = new URL(path);
                    //获取连接
                    HttpURLConnection connection = (HttpURLConnection) url.openConnection();
                    //使用GET方法访问网络
                    connection.setRequestMethod("GET");
                    //超时时间为10秒
                    connection.setConnectTimeout(10000);
                    //获取返回码
                    int code = connection.getResponseCode();
                    if (code == 200) {
                        InputStream inputStream = connection.getInputStream();
                        //使用工厂把网络的输入流生产Bitmap
                        Bitmap bitmap = BitmapFactory.decodeStream(inputStream);
                        //利用Message把图片发给Handler
                        Message msg = Message.obtain();
                        msg.obj = bitmap;
                        msg.what = GET_DATA_SUCCESS;
                        handler.sendMessage(msg);
                          inputStream.close();
                    }else {
                        //服务启发生错误
                        handler.sendEmptyMessage(SERVER_ERROR);
                    }
                } catch (IOException e) {
                    e.printStackTrace();
                    //网络连接错误
                    handler.sendEmptyMessage(NETWORK_ERROR);
                }
            }
        }.start();
    }

}

3、activity的逻辑代码

package com.me.androidstudy2;

import android.app.Activity;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;

import com.google.gson.Gson;
import com.me.androidstudy2.adapter.NewAdapter;
import com.me.androidstudy2.domain.News;
import com.me.androidstudy2.utils.HttpUtil;

public class XwActivity extends Activity {
    private News news = new News();
    private RecyclerView recyclerView;
    private SentUrlTask sentUrlTask;
    private NewAdapter adapter = new NewAdapter();

    public void initView(){
        recyclerView = findViewById(R.id.rv_news);
    }

    public void action(){
        sentUrlTask = new SentUrlTask("http://3g.163.com/touch/reconstruct/article/list/BBM54PGAwangning/0-20.html");
        sentUrlTask.execute();

    }

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_xw);
        initView();
        action();
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        if (sentUrlTask != null) {
            sentUrlTask.cancel(true);
        }
    }

    private class SentUrlTask extends AsyncTask<Void,Void,String> {

        private  String url;

        public SentUrlTask(String url) {
            this.url = url;
        }

        @Override
        protected String doInBackground(Void... voids) {
            return HttpUtil.setUrl(url);
        }

        @Override
        protected void onPostExecute(@NonNull String s) {
            super.onPostExecute(s);
            Gson gson = new Gson();
            String ss = s.substring(9,s.length()-1);
            news = gson.fromJson(ss, News.class);
            adapter.setData(news.getBBM54PGAwangning());
            recyclerView.setAdapter(adapter);
            recyclerView.setLayoutManager(new LinearLayoutManager(XwActivity.this));
            recyclerView.setAdapter(adapter);
            Log.e("new-ss:",news.getBBM54PGAwangning().get(0).getTitle());
        }
    }

}

4、新闻列表的适配器：

1）MyViewHolder

package com.me.androidstudy2.adapter;

import android.view.View;
import android.widget.ImageView;
import android.widget.TextView;

import androidx.annotation.NonNull;
import androidx.recyclerview.widget.RecyclerView;

import com.me.androidstudy2.R;
import com.me.androidstudy2.view.MyImageView;

class MyViewHolder extends RecyclerView.ViewHolder {
    TextView title ;
    TextView content ;
    TextView date ;
    MyImageView img ;

    public MyViewHolder(@NonNull View itemView) {
        super(itemView);
        title = itemView.findViewById(R.id.tv_title);
        content = itemView.findViewById(R.id.tv_content);
        date = itemView.findViewById(R.id.tv_date);
        img = itemView.findViewById(R.id.iv_new);
    }
}

2）NewAdapter

package com.me.androidstudy2.adapter;

import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;

import androidx.annotation.NonNull;
import androidx.recyclerview.widget.RecyclerView;

import com.me.androidstudy2.R;
import com.me.androidstudy2.domain.New;

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

public class NewAdapter extends RecyclerView.Adapter<MyViewHolder> {
    List<New> data ;

    public List<New> getData() {
        return data;
    }

    public void setData(List<New> data) {
        this.data = data;
    }

    @NonNull
    @Override
    public MyViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        LayoutInflater layoutInflater = LayoutInflater.from(parent.getContext());
        View itemView = layoutInflater.inflate(R.layout.item_layout,parent,false);
        return new MyViewHolder(itemView);
    }

    @Override
    public void onBindViewHolder(@NonNull MyViewHolder holder, int position) {
        holder.img.setImageURL(data.get(position).getImgsrc());
        holder.content.setText(data.get(position).getDigest());
        holder.title.setText(data.get(position).getTitle());
        holder.date.setText(data.get(position).getPtime());
    }

    @Override
    public int getItemCount() {
        return data.size();
    }
}

5、新闻实体：

1）New

package com.me.androidstudy2.domain;

public class New {
    private String title;
    private String imgsrc;
    private String digest;
    private String ptime;

    public String getPtime() {
        return ptime;
    }

    public void setPtime(String ptime) {
        this.ptime = ptime;
    }

    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }

    public String getImgsrc() {
        return imgsrc;
    }

    public void setImgsrc(String imgsrc) {
        this.imgsrc = imgsrc;
    }

    public String getDigest() {
        return digest;
    }

    public void setDigest(String digest) {
        this.digest = digest;
    }
}

2）News

package com.me.androidstudy2.domain;

import java.util.List;

public class News {
    private List<New> BBM54PGAwangning;
    private List<New> BA10TA81wangning;
    private List<New> BA8E6OEOwangning;
    private List<New> BA8EE5GMwangning;
    private List<New> BAI67OGGwangning;
    private List<New> BA8D4A3Rwangning;
    private List<New> BAI6I0O5wangning;
    private List<New> BAI6JOD9wangning;
    private List<New> BA8F6ICNwangning;
    private List<New> BAI6RHDKwangning;
    private List<New> BA8FF5PRwangning;
    private List<New> BDC4QSV3wangning;
    private List<New> BEO4GINLwangning;

    public List<New> getBA10TA81wangning() {
        return BA10TA81wangning;
    }

    public void setBA10TA81wangning(List<New> BA10TA81wangning) {
        this.BA10TA81wangning = BA10TA81wangning;
    }

    public List<New> getBA8E6OEOwangning() {
        return BA8E6OEOwangning;
    }

    public void setBA8E6OEOwangning(List<New> BA8E6OEOwangning) {
        this.BA8E6OEOwangning = BA8E6OEOwangning;
    }

    public List<New> getBA8EE5GMwangning() {
        return BA8EE5GMwangning;
    }

    public void setBA8EE5GMwangning(List<New> BA8EE5GMwangning) {
        this.BA8EE5GMwangning = BA8EE5GMwangning;
    }

    public List<New> getBAI67OGGwangning() {
        return BAI67OGGwangning;
    }

    public void setBAI67OGGwangning(List<New> BAI67OGGwangning) {
        this.BAI67OGGwangning = BAI67OGGwangning;
    }

    public List<New> getBA8D4A3Rwangning() {
        return BA8D4A3Rwangning;
    }

    public void setBA8D4A3Rwangning(List<New> BA8D4A3Rwangning) {
        this.BA8D4A3Rwangning = BA8D4A3Rwangning;
    }

    public List<New> getBAI6I0O5wangning() {
        return BAI6I0O5wangning;
    }

    public void setBAI6I0O5wangning(List<New> BAI6I0O5wangning) {
        this.BAI6I0O5wangning = BAI6I0O5wangning;
    }

    public List<New> getBAI6JOD9wangning() {
        return BAI6JOD9wangning;
    }

    public void setBAI6JOD9wangning(List<New> BAI6JOD9wangning) {
        this.BAI6JOD9wangning = BAI6JOD9wangning;
    }

    public List<New> getBA8F6ICNwangning() {
        return BA8F6ICNwangning;
    }

    public void setBA8F6ICNwangning(List<New> BA8F6ICNwangning) {
        this.BA8F6ICNwangning = BA8F6ICNwangning;
    }

    public List<New> getBAI6RHDKwangning() {
        return BAI6RHDKwangning;
    }

    public void setBAI6RHDKwangning(List<New> BAI6RHDKwangning) {
        this.BAI6RHDKwangning = BAI6RHDKwangning;
    }

    public List<New> getBA8FF5PRwangning() {
        return BA8FF5PRwangning;
    }

    public void setBA8FF5PRwangning(List<New> BA8FF5PRwangning) {
        this.BA8FF5PRwangning = BA8FF5PRwangning;
    }

    public List<New> getBDC4QSV3wangning() {
        return BDC4QSV3wangning;
    }

    public void setBDC4QSV3wangning(List<New> BDC4QSV3wangning) {
        this.BDC4QSV3wangning = BDC4QSV3wangning;
    }

    public List<New> getBEO4GINLwangning() {
        return BEO4GINLwangning;
    }

    public void setBEO4GINLwangning(List<New> BEO4GINLwangning) {
        this.BEO4GINLwangning = BEO4GINLwangning;
    }

    public List<New> getBBM54PGAwangning() {
        return BBM54PGAwangning;
    }

    public void setBBM54PGAwangning(List<New> BBM54PGAwangning) {
        this.BBM54PGAwangning = BBM54PGAwangning;
    }
}

6、新闻项的布局

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="horizontal" android:layout_width="match_parent"
    android:layout_height="wrap_content">
    <com.me.androidstudy2.view.MyImageView
        android:id="@+id/iv_new"
        android:layout_width="100dp"
        android:layout_height="100dp"
        android:layout_margin="4dp"/>
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:gravity="center"
        android:padding="4dp"
        android:orientation="vertical">
        <TextView
            android:id="@+id/tv_title"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:textSize="24dp"
            android:maxLines="1"
            android:text="title"/>
        <TextView
            android:id="@+id/tv_content"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:textSize="13dp"
            android:maxLines="3"
            android:text="content"/>
        <TextView
            android:id="@+id/tv_date"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:gravity="right"
            android:textSize="10dp"
            android:layout_marginRight="5dp"
            android:text="content"/>
    </LinearLayout>

</LinearLayout>

7、activity的布局：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" android:layout_width="match_parent"
    android:layout_height="match_parent">


    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/rv_news"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />
</LinearLayout>