Android在ImageView上直接显示网络图片Handler使用

XML

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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"
    android:orientation="vertical"
    tools:context=".HtttpPicActivity">

    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="获取"
        android:id="@+id/img_get"
        />

    <ImageView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:src="@drawable/diglett"
        android:id="@+id/img_url"
        />



</LinearLayout>

JAVA

package com.example.network;

import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;

import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.Toast;

import java.io.IOException;
import java.io.InputStream;
import java.lang.ref.WeakReference;
import java.net.HttpURLConnection;
import java.net.URL;

public class HtttpPicActivity extends AppCompatActivity {


    public static final String HTTP_URL = "https://img2.mukewang.com/5adfee7f0001cbb906000338-240-135.jpg";
    public static final int CODE = 100005;
    public static final int SERVER_ERROR = 100006;
    private Button mImgGet;
    private ImageView mImgUrl;
    private MyHandler myHandler;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_htttp_pic);

        mImgGet = (Button) findViewById(R.id.img_get);
        mImgUrl = (ImageView) findViewById(R.id.img_url);

        myHandler = new MyHandler(this);


        mImgGet.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                new Thread() {
                    @Override
                    public void run() {
                        super.run();
                        try {
                            Thread.sleep(1000);
                            getUrlimg(HTTP_URL);

                        } catch (InterruptedException e) {
                            e.printStackTrace();
                        }
                    }
                }.start();

            }
        });


    }


    public void getUrlimg(String path) {
        //把传过来的路径转成URL
        try {
            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 = CODE;
                myHandler.sendMessage(msg);
                inputStream.close();
            } else {
                //服务启发生错误
                myHandler.sendEmptyMessage(SERVER_ERROR);
            }

        } catch (IOException e) {
            e.printStackTrace();
        }
        //获取连接
    }


    public static class MyHandler extends Handler {
        final WeakReference<HtttpPicActivity> weakReference;

        public MyHandler(HtttpPicActivity activity) {
            this.weakReference = new WeakReference<>(activity);
        }


        @Override
        public void handleMessage(@NonNull Message msg) {
            super.handleMessage(msg);
            HtttpPicActivity activity = weakReference.get();

            switch (msg.what) {
                case CODE:
                    Bitmap bitmap = (Bitmap) msg.obj;
                    activity.mImgUrl.setImageBitmap(bitmap);
                    break;
                case SERVER_ERROR:
                    Toast.makeText(activity, "网络异常", Toast.LENGTH_SHORT).show();
                    break;
            }

        }
    }


}

AndroidManifest.xml加入访问网络权限

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