package com.hxc.supreme.activity;import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.AsyncTask;
import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.v4.app.FragmentTransaction;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.TextView;import com.hxc.supreme.R;
import com.hxc.supreme.fragment.QuickControlFragment;import java.io.BufferedInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;/*** created by huxc  on 2017/9/28.* func：asynctask异步下载* email: hxc242313@qq.com*/public class AsyncTaskActivity extends AppCompatActivity implements View.OnClickListener {private Button btnDownload;private ImageView ivImage;private TextView tvProgress;private final String url = "http://i10.hoopchina.com.cn/hupuapp/bbs/741/36556741/thread_4847_36556741_20180619162627_83601.jpg?x-oss-process=image/resize,w_800/format,jpg";@Overrideprotected void onCreate(@Nullable Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_asynctask);initView();initListener();initData();}protected void initView() {btnDownload = (Button) findViewById(R.id.btn_download);ivImage = (ImageView) findViewById(R.id.iv_image);tvProgress = (TextView) findViewById(R.id.tv_progress);}protected void initListener() {btnDownload.setOnClickListener(this);}protected void initData() {}@Overridepublic void onClick(View view) {if (view == btnDownload) {MyAsyncTask asyncTask = new MyAsyncTask();asyncTask.execute(url);}}class MyAsyncTask extends AsyncTask<String, String, Bitmap> {@Overrideprotected void onPreExecute() {super.onPreExecute();tvProgress.setText("下载开始");}@Overrideprotected Bitmap doInBackground(String... strings) {publishProgress("正在下载中...");return getBitmapFromUrl(strings[0]);}@Overrideprotected void onProgressUpdate(String... values) {super.onProgressUpdate(values);tvProgress.setText("正在下载中...");}@Overrideprotected void onPostExecute(Bitmap bitmap) {super.onPostExecute(bitmap);ivImage.setImageBitmap(bitmap);tvProgress.setText("下载结束");}}public Bitmap getBitmapFromUrl(String urlString) {Bitmap bitmap;InputStream is = null;try {URL url = new URL(urlString);HttpURLConnection connection = (HttpURLConnection) url.openConnection();is = new BufferedInputStream(connection.getInputStream());bitmap = BitmapFactory.decodeStream(is);connection.disconnect();return bitmap;} catch (MalformedURLException e) {e.printStackTrace();} catch (IOException e) {e.printStackTrace();} finally {try {is.close();} catch (IOException e) {e.printStackTrace();}}return null;}}

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"xmlns:app="http://schemas.android.com/apk/res-auto"android:layout_width="match_parent"android:layout_height="match_parent"><ImageViewandroid:id="@+id/iv_image"android:layout_width="300dp"android:layout_height="400dp"android:layout_marginLeft="20dp"android:layout_marginTop="20dp"app:layout_constraintLeft_toLeftOf="parent"app:layout_constraintTop_toTopOf="parent" /><TextViewandroid:id="@+id/tv_pro"android:layout_width="wrap_content"android:layout_height="wrap_content"android:layout_marginLeft="20dp"android:text="当前下载进度："app:layout_constraintLeft_toLeftOf="@+id/iv_image"app:layout_constraintTop_toBottomOf="@+id/iv_image" /><TextViewandroid:id="@+id/tv_progress"android:layout_width="wrap_content"android:layout_height="wrap_content"android:layout_marginLeft="20dp"app:layout_constraintLeft_toRightOf="@+id/tv_pro"app:layout_constraintTop_toTopOf="@+id/tv_pro" /><Buttonandroid:id="@+id/btn_download"android:layout_width="match_parent"android:layout_height="40dp"android:layout_margin="20dp"android:background="@drawable/shape_config_btn_bg"android:text="开始下载"app:layout_constraintBottom_toBottomOf="parent" /></android.support.constraint.ConstraintLayout>