package com.example.www.checkimage;

import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.EditText;
import android.widget.ImageView;
import android.widget.Toast;

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

public class MainActivity extends AppCompatActivity {

 private EditText mPt_url;
 private ImageView mIv_show;
 private Handler mHandler = new Handler(){
 @Override
 public void handleMessage(Message msg) {
 if(msg.what == 1){
 Bitmap bitmap = (Bitmap) msg.obj;
 mIv_show.setImageBitmap(bitmap);
 Toast.makeText(getApplicationContext(), "图片展示成功", Toast.LENGTH_LONG).show();
 }
 }
 };

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

 mPt_url = (EditText) findViewById(R.id.pt_url);
 mIv_show = (ImageView) findViewById(R.id.imageCon);
 }

 public void checkImage(View v) {
 new Thread(){
 @Override
 public void run() {

 try {
  String path = mPt_url.getText().toString().trim();
  URL url = new URL(path);
  HttpURLConnection conn = (HttpURLConnection) url.openConnection();
  conn.setRequestMethod("GET");
  conn.setConnectTimeout(5000);
  int responseCode = conn.getResponseCode();
  if(responseCode == 200) {
  InputStream is = conn.getInputStream();


  Bitmap bitmap = BitmapFactory.decodeStream(is);

  Message msg = Message.obtain(); // 创建 消息
  msg.obj = bitmap;
  msg.what = 1;


  mHandler.sendMessage(msg);
  }
 } catch (Exception e) {
  e.printStackTrace();
 }

 }
 }.start();
 }
}

<?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"
 xmlns:tools="http://schemas.android.com/tools"
 android:layout_width="match_parent"
 android:layout_height="match_parent"
 tools:context=".MainActivity">

 <EditText
 android:id="@+id/pt_url"
 android:layout_width="368dp"
 android:layout_height="wrap_content"
 android:layout_marginStart="8dp"
 android:layout_marginTop="8dp"
 android:layout_marginEnd="8dp"
 android:ems="10"
 android:hint="请输入与图片地址"
 android:inputType="textPersonName"
 app:layout_constraintEnd_toEndOf="parent"
 app:layout_constraintStart_toStartOf="parent"
 app:layout_constraintTop_toTopOf="parent" />

 <Button
 android:id="@+id/button"
 android:layout_width="wrap_content"
 android:layout_height="wrap_content"
 android:layout_marginStart="8dp"
 android:layout_marginTop="8dp"
 android:layout_marginEnd="8dp"
 android:text="Button"
 app:layout_constraintEnd_toEndOf="parent"
 app:layout_constraintHorizontal_bias="0.0"
 app:layout_constraintStart_toStartOf="parent"
 android:onClick="checkImage"
 app:layout_constraintTop_toBottomOf="@+id/pt_url" />

 <ImageView
 android:id="@+id/imageCon"
 android:layout_width="0dp"
 android:layout_height="0dp"
 android:layout_marginStart="8dp"
 android:layout_marginTop="8dp"
 android:layout_marginEnd="8dp"
 android:layout_marginBottom="8dp"
 app:layout_constraintBottom_toBottomOf="parent"
 app:layout_constraintEnd_toEndOf="parent"
 app:layout_constraintStart_toStartOf="parent"
 app:layout_constraintTop_toBottomOf="@+id/button"
 app:srcCompat="@mipmap/ic_launcher" />
</android.support.constraint.ConstraintLayout>

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

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

 <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>