1.佈局程式碼：

<LinearLayout xmlns:Android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context=".MainActivity" >

    <ImageView
        android:id="@+id/iv"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:layout_weight="1" />

    <EditText
        android:id="@+id/et_path"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:hint="請輸入圖片路徑"
        android:text="http://b.hiphotos.baidu.com/image/w%3D310/sign=a439f5b24510b912bfc1f0fff3fdfcb5/83025aafa40f4bfb92c52c5d014f78f0f73618a5.jpg"
        android:maxLines="1" />

    <Button
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:onClick="click"
        android:text="瀏覽" />

</LinearLayout>

2.編寫頁面互動程式碼：

package cn.edu.bzu.imageviewdemo;

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.text.TextUtils;
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 {

    protected static final int CHANGE_UI = 1;
    protected static final int ERROR = 2;
    private EditText et_path;
    private ImageView iv;
    // 主執行緒建立訊息處理器
    private Handler handler = new Handler(){
        public void handleMessage(android.os.Message msg) {
            if(msg.what == CHANGE_UI){
                Bitmap bitmap = (Bitmap) msg.obj;
                iv.setImageBitmap(bitmap);
            }else if(msg.what == ERROR){
                Toast.makeText(MainActivity.this, "顯示圖片錯誤", 0).show();
            }
        };
    };
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        et_path = (EditText) findViewById(R.id.et_path);
        iv = (ImageView) findViewById(R.id.iv);
    }
    public void click(View view) {
        final String path = et_path.getText().toString().trim();
        if (TextUtils.isEmpty(path)) {
            Toast.makeText(this, "圖片路徑不能為空", Toast.LENGTH_SHORT).show();
        } else {
            //子執行緒請求網路,Android4.0以後訪問網路不能放在主執行緒中
            new Thread() {
                public void run() {
                    // 連線伺服器 get 請求 獲取圖片.
                    try {
                        URL url = new URL(path);       //建立URL物件
                        // 根據url 傳送 http的請求.
                        HttpURLConnection conn = (HttpURLConnection) url
                                .openConnection();
                        // 設定請求的方式
                        conn.setRequestMethod("GET");
                        //設定超時時間
                        conn.setConnectTimeout(5000);
                        // 得到伺服器返回的響應碼
                        int code = conn.getResponseCode();
                        //請求網路成功後返回碼是200
                        if (code == 200) {
                            //獲取輸入流
                            InputStream is = conn.getInputStream();
                            //將流轉換成Bitmap物件
                            Bitmap bitmap = BitmapFactory.decodeStream(is);
                            //iv.setImageBitmap(bitmap);
                            //TODO: 告訴主執行緒一個訊息:幫我更改介面。內容:bitmap
                            Message msg = new Message();
                            msg.what = CHANGE_UI;
                            msg.obj = bitmap;
                            handler.sendMessage(msg);
                        } else {
                            //返回碼不是200  請求伺服器失敗
                            Message msg = new Message();
                            msg.what = ERROR;
                            handler.sendMessage(msg);
                        }
                    } catch (Exception e) {
                        e.printStackTrace();
                        Message msg = new Message();
                        msg.what = ERROR;
                        handler.sendMessage(msg);
                    }
                };
            }.start();
        }
    }

}

3.在清單檔案下新增如下程式碼：

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