android 加载图片

package mydemo.mycom.demo2;

import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.text.TextUtils;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
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 ImagePrev extends ActionBarActivity implements View.OnClickListener {

    private ImageView iv;
    private Button btn_prev_image;
    private EditText et_image_path;


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

        iv = (ImageView)findViewById(R.id.iv);
        btn_prev_image = (Button)findViewById(R.id.btn_prev_image);
        et_image_path = (EditText)findViewById(R.id.et_image_path);
        btn_prev_image.setOnClickListener(this);

    }


    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.menu_image_prev, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        int id = item.getItemId();
        if (id == R.id.action_settings) {
            return true;
        }
        return super.onOptionsItemSelected(item);
    }

    @Override
    public void onClick(View view) {
        switch (view.getId())
        {
            case R.id.btn_prev_image:
                String path = et_image_path.getText().toString().trim();
                if(TextUtils.isEmpty(path))
                {
                    Toast.makeText(this,"图片路径不能",Toast.LENGTH_SHORT).show();
                    return;
                }
                try
                {
                    //浏览图片
                    URL url  = new URL(path);
                    HttpURLConnection conn = (HttpURLConnection)url.openConnection();

                    conn.setRequestMethod("GET");
                    conn.setConnectTimeout(5000);
                    int code = conn.getResponseCode();
                    if(code==200)
                    {
                        InputStream is = conn.getInputStream();
                        Bitmap bitmap = BitmapFactory.decodeStream(is);
                        iv.setImageBitmap(bitmap);
                    }
                    else
                    {
                        Toast.makeText(this,"图片浏览失败",Toast.LENGTH_SHORT).show();
                    }
                }catch (Exception e)
                {
                    Toast.makeText(this,"图片浏览失败",Toast.LENGTH_SHORT).show();
                    e.printStackTrace();
                }
                break;
        }
    }
}

<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:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:orientation="vertical"
    tools:context="mydemo.mycom.demo2.ImagePrev">

    <ImageView
        android:layout_weight="1000"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:id="@+id/iv"/>
    <EditText
        android:text="http://192.168.1.1:91/Resource/TopicInfo/2015-05-23/130768288778069472.png"
        android:hint="图片路径"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:id="@+id/et_image_path"/>

    <Button
        android:text="浏览"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:id="@+id/btn_prev_image"/>
</LinearLayout>