package org.lxh.util;
import java.io.ByteArrayOutputStream;
import java.io.InputStream;
public class StreamTool {
  public static byte[] readInputStream(InputStream in) throws Exception{
    int len=0;
    byte buf[]=new byte[1024];
    ByteArrayOutputStream out=new ByteArrayOutputStream();
    while((len=in.read(buf))!=-1){
      out.write(buf,0,len); //把数据写入内存
    }
    out.close(); //关闭内存输出流
    return out.toByteArray(); //把内存输出流转换成byte数组
  }
}

package org.lxh.service;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import org.lxh.util.StreamTool;
import android.util.Log;
public class WebService {
  public static byte[] getImage(String path){
    URL url;
    byte[] b=null;
    try {
      url = new URL(path);  //设置URL
      HttpURLConnection con;
      con = (HttpURLConnection)url.openConnection(); //打开连接
      con.setRequestMethod("GET"); //设置请求方法
      //设置连接超时时间为5s
      con.setConnectTimeout(5000);
      InputStream in=con.getInputStream(); //取得字节输入流
      b=StreamTool.readInputStream(in);
    } catch (Exception e) {
      e.printStackTrace();
    }
    return b; //返回byte数组
  }
}

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
  android:orientation="vertical"
  android:layout_width="fill_parent"
  android:layout_height="fill_parent"
  >
<TextView
  android:layout_width="fill_parent"
  android:layout_height="wrap_content"
  android:text="@string/hello"
  />
  <TextView
  android:layout_width="fill_parent"
  android:layout_height="wrap_content"
  android:text="@string/picaddress"
  />
  <EditText
  android:layout_width="wrap_content"
  android:layout_height="wrap_content"
  android:text="http://www.desk9.com/Desk9Image/21/Desk9_21_1690_35790_S.jpg"
  android:id="@+id/imageaddress"
  />
  <Button
   android:layout_width="wrap_content"
  android:layout_height="wrap_content"
  android:text="@string/look"
  android:id="@+id/button"
  />
  <ImageView
   android:layout_width="fill_parent"
  android:layout_height="fill_parent"
  android:id="@+id/image"/>
</LinearLayout>

package org.lxh.net;
import org.lxh.service.WebService;
import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ImageView;
import android.widget.Toast;
public class NetActivity extends Activity {
  private EditText picaddress;
  private Button button;
  private ImageView imageView;
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    button=(Button)this.findViewById(R.id.button);
    imageView=(ImageView)this.findViewById(R.id.image);
    picaddress=(EditText)this.findViewById(R.id.imageaddress);
    button.setOnClickListener(new View.OnClickListener() {
      public void onClick(View v) {
        String address=picaddress.getText().toString();
        try {
          byte[] data=WebService.getImage(address); //得到图片的输入流
          //二进制数据生成位图
          Bitmap bit=BitmapFactory.decodeByteArray(data, 0, data.length);
          imageView.setImageBitmap(bit);
        } catch (Exception e) {
          Log.e("NetActivity", e.toString());
          Toast.makeText(NetActivity.this, R.string.error, 1).show();
        }
      }
    });
  }
}

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
   package="org.lxh.net"
   android:versionCode="1"
   android:versionName="1.0">
  <application android:icon="@drawable/icon" android:label="@string/app_name">
    <activity android:name=".NetActivity"
         android:label="@string/app_name">
      <intent-filter>
        <action android:name="android.intent.action.MAIN" />
        <category android:name="android.intent.category.LAUNCHER" />
      </intent-filter>
    </activity>
  </application>
  <uses-sdk android:minSdkVersion="7" />
  <uses-permission android:name="android.permission.INTERNET"/>
</manifest>

<?xml version="1.0" encoding="utf-8"?>
<resources>
  <string name="hello">Hello World, NetActivity!</string>
  <string name="app_name">图片查看</string>
  <string name="picaddress">图片地址</string>
  <string name="look">查看</string>
  <string name="error">网络连接异常</string>
</resources>