效果圖

實現原始碼：

layout

<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"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context=".MainActivity" >

    <ImageView
        android:id="@+id/ivImage"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:layout_weight="1" />

    <EditText
        android:id="@+id/etImageUrl"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:ems="10"
        android:hint="請輸入圖片的地址"
        android:text="http://avatar.csdn.net/C/9/A/1_yf210yf.jpg" />

    <Button
        android:id="@+id/btnView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:background="@drawable/button_bg"
        android:onClick="viewImage"
        android:text="瀏覽" />

</LinearLayout>
 

package com.bzu.gxs;

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

import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.text.TextUtils;
import android.view.Menu;
import android.view.View;
import android.widget.EditText;
import android.widget.ImageView;
import android.widget.Toast;

public class MainActivity extends Activity {
	private EditText etImageUrl;
	private ImageView ivImage;
	public static final int SHOWIMAGE = 1;
	public static final int SHOWFAIL = 0;
	// Handler 處理事件
	private Handler handler = new Handler() {
		public void handleMessage(android.os.Message msg) {
			switch (msg.what) {
			case SHOWIMAGE:
				Bitmap bitmap = (Bitmap) msg.obj;
				ivImage.setImageBitmap(bitmap);
				break;

			case SHOWFAIL:
				ivImage.setImageResource(R.drawable.button_bg);
				Toast.makeText(MainActivity.this, "顯示圖片失敗", Toast.LENGTH_LONG)
						.show();
				break;

			default:
				break;
			}
		};
	};

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		initViews();
		ivImage.setImageResource(R.drawable.button_bg);
	}

	// 查詢的ID
	private void initViews() {
		etImageUrl = (EditText) findViewById(R.id.etImageUrl);
		ivImage = (ImageView) findViewById(R.id.ivImage);
	}

	// 按鈕點選事件
	public void viewImage(View view) {
		final String imageUrl = etImageUrl.getText().toString();
		if (TextUtils.isEmpty(imageUrl)) {
			Toast.makeText(this, "圖片路徑不能為空", Toast.LENGTH_LONG).show();
		} else {
			new Thread() {
				public void run() {
					try {
						URL url = new URL(imageUrl);
						HttpURLConnection httpURLConnection = (HttpURLConnection) url
								.openConnection();
						httpURLConnection.setRequestMethod("GET");
						httpURLConnection.setConnectTimeout(5000);
						int responseCode = httpURLConnection.getResponseCode();
						if (responseCode == 200) {
							InputStream inputStream = httpURLConnection
									.getInputStream();
							Bitmap bitmap = BitmapFactory
									.decodeStream(inputStream);
							Message message = new Message();
							message.what = SHOWIMAGE;
							message.obj = bitmap;
							// ivImage.setImageBitmap(bitmap);
							handler.sendMessage(message);
						} else {
							Message message = new Message();
							message.what = SHOWFAIL;
							handler.sendMessage(message);
						}
					} catch (MalformedURLException e) {
						e.printStackTrace();
					} catch (IOException e) {
						e.printStackTrace();
					}
				}
			}.start();
		}
	}
}