xml:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#ffffff"
    android:orientation="vertical"
    tools:context="com.jiutouxiang.help.WebSourceViewerActivity">
    <EditText
        android:id="@+id/et_url"
        android:hint="请输入网址"
        android:textColor="#333333"
        android:textColorHint="#888888"
        android:text="https://ss0.bdstatic.com/5aV1bjqh_Q23odCf/static/superman/img/logo/bd_logo1_31bdc765.png"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />
    <Button
        android:id="@+id/bt_go"
        android:text="查看"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />
    <ScrollView
        android:layout_width="match_parent"
        android:layout_height="match_parent">
        <ImageView
            android:id="@+id/iv_picture"
            android:layout_width="match_parent"
            android:layout_height="match_parent" />
    </ScrollView>

</LinearLayout>

java:

package com.jiutouxiang.help;

import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ImageView;

import com.jiutouxiang.R;
import com.jiutouxiang.base.MyActivity;
import com.jiutouxiang.toolkits.ForLog;

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

public class PictureViewerActivity extends MyActivity {
    private ImageView iv_picture;
    private Button bt_go;
    private Activity activity;
    private EditText et_url;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_picture_viewer);
        iv_picture=(ImageView)findViewById(R.id.iv_picture);
        activity=this;
        et_url=(EditText)activity.findViewById(R.id.et_url);
        bt_go=(Button)activity.findViewById(R.id.bt_go);
        bt_go.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                new Thread(new Runnable() {
                    @Override
                    public void run() {
                        //获取路径
                        String path=et_url.getText().toString().trim();
                        getPictureByPath(path);
                    }
                }).start();

            }
        });
    }

    private void getPictureByPath(String path) {
        try {
            URL url=new URL(path);
            //拿到HttpURLConnection对象，用于接受和发送数据
            HttpURLConnection httpURLConnection= (HttpURLConnection) url.openConnection();
            //设置请求方式
            // httpURLConnection.setRequestMethod("GET");
            //设置请求超时时间:5s
            // httpURLConnection.setConnectTimeout(5000);
            //获取服务器返回响应吗
            int code=httpURLConnection.getResponseCode();
            if (code==200){
                //说明请求成功
                final InputStream in=httpURLConnection.getInputStream();
                final Bitmap bitmap=BitmapFactory.decodeStream(in);
                runOnUiThread(new Runnable() {
                    @Override
                    public void run() {
                        iv_picture.setImageBitmap(bitmap);
                    }
                });
            } else{
                ForLog.showError("返回代码错误："+code+"---"+path);
            }


        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}