java - 下载的图像未在 ImageView Android Studio 中显示

Question

我在使用 android studio 时遇到了一些问题。我正在尝试从 URL 下载图像，然后使用 AsyncTask 将其显示在 Imageview 中。但是当我单击按钮时，您看到的只是进度对话框，然后 ImageView 变为空白。

我确实在 list 文件中插入了使用互联网权限。

提前致谢

package com.phil.imagesdemo;

import androidx.appcompat.app.AppCompatActivity;

import android.app.ProgressDialog;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.AsyncTask;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;

import java.io.InputStream;

public class MainActivity extends AppCompatActivity {
    String url = "https://en.wikipedia.org/wiki/Bart_Simpson#/media/File:Bart_Simpson_200px.png";
    ImageView image;
    Button button;
    ProgressDialog mProgressDialog;


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

        image = (ImageView) findViewById(R.id.theImage);
        button = (Button) findViewById(R.id.button);

        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                new DownloadImage().execute(url);
            }
        });

    }

    private class DownloadImage extends AsyncTask{

        @Override
        protected Bitmap doInBackground(Object... urls) {
            String imageURL = (String)urls[0];
            Bitmap bitmap = null;
            try {
                // Download Image from URL
                InputStream input = new java.net.URL(imageURL).openStream();
                // Decode Bitmap
                bitmap = BitmapFactory.decodeStream(input);
            } catch (Exception e) {
                e.printStackTrace();
            }
            return bitmap;
        }

        @Override
        protected void onPostExecute(Object result) {
            super.onPostExecute(result);

            // Set the bitmap into ImageView
            image.setImageBitmap ((Bitmap)result);
            // Close progressdialog
            mProgressDialog.dismiss();
        }

        @Override
        protected void onPreExecute() {
            super.onPreExecute();
            mProgressDialog = new ProgressDialog(MainActivity.this);
            mProgressDialog.setTitle("Download Image Tutorial");
            mProgressDialog.setMessage("Loading...");
            mProgressDialog.setIndeterminate(false);
            mProgressDialog.show();
        }
    }



}

list 文件

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.phil.imagesdemo">

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

    <application
        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>

Answer 1

好吧，经过长时间的斗争，我发现错误消息是套接字失败:EPERM(不允许操作)。

我只需要从模拟器中卸载应用程序，然后再次运行