Android实现网络图片浏览功能

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;
 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, "显示图片错误", 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, "图片路径不能为空", Toast.LENGTH_SHORT).show();
  } else {
   new Thread() {
    public void run() {

     try {
      URL url = new URL(path);  //创建URL对象

      HttpURLConnection cOnn= (HttpURLConnection) url
        .openConnection();
      // 设置请求的方式
      conn.setRequestMethod("GET");
      //设置超时时间
      conn.setConnectTimeout(5000);

      int code = conn.getResponseCode();

      if (code == 200) {

       InputStream is = conn.getInputStream();

       Bitmap bitmap = BitmapFactory.decodeStream(is);
       //iv.setImageBitmap(bitmap);

       Message msg = new Message();
       msg.what = CHANGE_UI;
       msg.obj = bitmap;
       handler.sendMessage(msg);
      } else {

       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();
  }
 }

}