Android获取网络图片并显示

初始网络加载比较耗时,读者可以更加优化代码

xml:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:background="#465"
    android:orientation="vertical" android:layout_width="match_parent"
    android:gravity="center"
    android:layout_height="match_parent">


    <ImageView
        android:id="@+id/bitmap_image"
        android:layout_gravity="center"
        android:layout_width="310dp"
        android:layout_height="200dp">

    </ImageView>

    <Button
        android:id="@+id/img_button"
        android:textColor="#fff"
        android:background="#5456"
        android:textSize="15sp"
        android:text="下一张"
        android:layout_marginTop="20dp"
        android:layout_width="160dp"
        android:layout_height="50dp">

    </Button>


</LinearLayout>

注意加上权限:

注意加上权限
    <uses-permission android:name="android.permission.WRITE_HISTORY_BOOKMARKS>"></uses-permission>
    <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"></uses-permission>
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"></uses-permission>
    <uses-permission android:name="android.permission.INTERNET" />
    <uses-permission android:name="android.permission.READ_PHONE_STATE" />
    <uses-permission android:name="android.permission.CHANGE_NETWORK_STATE" />
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
    <uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />

activity:

package fengxing.primer.shouce.net_image;

import android.app.Activity;
import android.content.Context;
import android.content.SharedPreferences;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Bundle;
import android.os.Environment;
import android.os.Handler;
import android.os.Message;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.Toast;

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;

import java.io.IOException;
import java.io.InputStream;
import java.util.LinkedList;
import java.util.List;

import fengxing.primer.shouce.R;
import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.Response;

public class NetImagesActivity extends Activity {

    private final static int SHOW_NET_IMAGE = 0;
    private final static String TAG="NetImagesActivity";
    private List<Bitmap> bitmapList = new LinkedList<Bitmap>();
    private Button button;
    private ImageView imageView;
    private List<String> urlList = new LinkedList<String>();
    private OkHttpClient okHttpClient = new OkHttpClient();
    private InputStream inputStream = null;
    private Response response=null;
    private Request request=null;
    private int index = 0;


    private Handler handler = new Handler(){
        @Override
        public void handleMessage(@NonNull Message msg) {
            super.handleMessage(msg);

            switch (msg.what){
                case SHOW_NET_IMAGE:
                {
                    switchImages();
                }
                    break;
                default:
                    break;
            }
        }
    };

    /**
     * 初始化界面
     * @param savedInstanceState
     */
    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_net_image);

        initData();
        initView();
        loadImages();

    }



    /**
     * 切换图片
     */
    private void switchImages() {
        if (bitmapList.size()>0) {
            if (bitmapList.size()==urlList.size()) {
                Toast.makeText(NetImagesActivity.this, "第: " + index + "张", Toast.LENGTH_SHORT).show();
                if (index < bitmapList.size()) {
                    imageView.setImageBitmap(bitmapList.get(index));
                    index++;
                    if (index >= bitmapList.size()) {
                        index = 0;
                    }
                }
            }
        }else{
            Toast.makeText(NetImagesActivity.this,"图片正在加载...",Toast.LENGTH_SHORT).show();
        }
    }

    /**
     * 加载网络图片
     */
    private void loadImages() {
        new Thread(new Runnable() {
            @Override
            public void run() {
                for (int i = 0 ; i < urlList.size();i++){
                    request = new Request.Builder()
                            .get()
                            .url(urlList.get(i))
                            .build();

                    try {
                        response = okHttpClient.newCall(request).execute();
                        if (response.isSuccessful()){
                            inputStream = response.body().byteStream();
                            bitmapList.add(BitmapFactory.decodeStream(inputStream));
                        }
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }

                button.setText("加载完成(显示图片)");

            }
        }).start();
    }

    /**
     * 初始化控件
     */
    private void initView() {
        button = findViewById(R.id.img_button);
        button.setText("图片加载中...");
        imageView=findViewById(R.id.bitmap_image);

        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Message message = new Message();
                message.what=SHOW_NET_IMAGE;
                handler.sendMessage(message);
            }
        });
    }

    /**
     * 初始化数据
     */
    private void initData() {
        urlList.add("https://i.loli.net/2019/10/07/CcSrLmoInxZtedp.jpg");
        urlList.add("https://i.loli.net/2019/10/07/nfdZYmVGzawI1yP.jpg");
        urlList.add("https://i.loli.net/2019/10/07/hewX2FuEfDmKQTI.jpg");
    }


    /**
     * 关闭资源
     */
    @Override
    protected void onDestroy() {
        super.onDestroy();
        if (inputStream!=null){
            try {
                inputStream.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }


    /**
     * 关闭activity之前保存数据
     */
    @Override
    protected void onStop() {
        super.onStop();
    }
}

效果图