捕获.PNG    

AndroidManifest.xml    

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.zdcrobot.handlermessage">
    <uses-permission android:name="android.permission.INTERNET"></uses-permission>
    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity
            android:name=".MainActivity"
            android:label="@string/app_name"
            android:theme="@style/AppTheme.NoActionBar">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

activity_main.xml    

<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout 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:fitsSystemWindows="true"
    tools:context="com.zdcrobot.handlermessage.MainActivity">

    <LinearLayout
        android:orientation="vertical"
        android:layout_width="match_parent"
        android:layout_height="match_parent">
        <Button
            android:id="@+id/button1"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="加载图片"/>
        <ImageView
            android:id="@+id/image1"
            android:layout_width="match_parent"
            android:layout_height="500dp" />
    </LinearLayout>

</android.support.design.widget.CoordinatorLayout>

MainActivity.class    

package com.zdcrobot.handlermessage;

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.Button;
import android.widget.ImageView;

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

public class MainActivity extends AppCompatActivity {
    private Button button;
    private ImageView imageView;
    private String imagPath = "http://pica.nipic.com/2007-11-09/200711912453162_2.jpg";
    private final int IS_FINISH = 1;
    private Handler handler = new Handler(){
        @Override
        public void handleMessage(Message msg) {
           Bitmap bitmap = (Bitmap)msg.obj;
            imageView.setImageBitmap(bitmap);
        }
    };
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        button = (Button)findViewById(R.id.button1);
        imageView = (ImageView)findViewById(R.id.image1);
        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                new Thread(new MyClass()).start();
            }
        });
    }

    public class MyClass implements Runnable{

        @Override
        public void run() {
            Bitmap bitmap = null;
            try {
                URL url = new URL(imagPath);
                HttpURLConnection httpURLConnection = (HttpURLConnection)url.openConnection();
                httpURLConnection.setDoInput(true);
                httpURLConnection.connect();
                InputStream inputStream = httpURLConnection.getInputStream();
                bitmap = BitmapFactory.decodeStream(inputStream);
            } catch (MalformedURLException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            }
            Message message = Message.obtain();
            message.obj = bitmap;
            message.what = IS_FINISH;
            handler.sendMessage(message);
        }
    }
}