java 

package app.android.demo;import android.os.AsyncTask;import android.os.Bundle;import android.telephony.TelephonyManager;import android.util.Log;import java.io.IOException;import java.net.URL;import android.app.Activity;import android.content.Context;import android.graphics.drawable.Drawable;import android.net.ConnectivityManager;import android.net.NetworkInfo;import android.view.Menu;import android.view.View;import android.view.View.OnClickListener;import android.widget.Button;import android.widget.ImageView;import android.widget.TextView;import android.widget.Toast;public class MainActivity extends Activity{    private ImageView mImageView = null ;    Button mButton1;    Button mButton2;    Button mButton3;    Button mButton4;    TextView mTextView;    TextView mTextView1;    ConnectivityManager connectMgr;    NetworkInfo[] networkInfo;    //The image url we are downloading from internet .    private final String IMAGE_URL1 = "http://a.hiphotos.baidu.com/image/pic/item/c2fdfc039245d688acbcd54ba0c27d1ed31b24a6.jpg" ;    private final String IMAGE_URL2 = "http://imgsrc.baidu.com/forum/w%3D580/sign=f9f1029647166d223877159c76230945/b69ad3f9d72a6059892764472c34349b023bbaca.jpg" ;    private final String IMAGE_URL3 = "http://static.open-open.com/lib/uploadImg/20130810/20130810175659_519.jpg" ;    private final String IMAGE_URL4 = "http://imgsrc.baidu.com/forum/w%3D580/sign=f9f1029647166d223877159c76230945/b69ad3f9d72a6059892764472c34349b023bbaca.jpg" ;        @Override    protected void onCreate(Bundle savedInstanceState)    {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);                               mImageView = (ImageView)this.findViewById(R.id.imageView1) ;        mButton1=(Button) findViewById(R.id.button1);        mButton2=(Button) findViewById(R.id.button2);                      mTextView=(TextView) findViewById(R.id.txt_show);        mTextView1=(TextView) findViewById(R.id.textView1);                if (isNetworkAvailable(MainActivity.this))        {                      mButton1.setOnClickListener(new Button1Lislen());            mButton2.setOnClickListener(new Button2Lislen());            mTextView1.setText("当前网络:=>可用");            Toast.makeText(getApplicationContext(), "当前有可用网络！", Toast.LENGTH_LONG).show();        }        else        {            mTextView1.setText("当前网络:=>不可用");            Toast.makeText(getApplicationContext(), "当前没有可用网络！", Toast.LENGTH_LONG).show();        }         }   class Button1Lislen implements OnClickListener   {    @Override     public void onClick(View v)     {        new Thread(new Runnable(){            @Override            public void run() {                // TODO Auto-generated method stub                final Drawable drawable = loadImageFromNetwork(IMAGE_URL1);                                mImageView.post(new Runnable(){                    @Override                    public void run() {                        // TODO Auto-generated method stub                                                mImageView.setImageDrawable(drawable) ;                                              }}) ;            }                    }).start()  ;                     }   }            private Drawable loadImageFromNetwork(String imageUrl)    {        Drawable drawable = null;        try {            drawable = Drawable.createFromStream(                    new URL(imageUrl).openStream(), "image.gif");        } catch (IOException e) {            Log.d("test", e.getMessage());        }        if (drawable == null) {            Log.d("test", "null drawable");        } else {            Log.d("test", "not null drawable");        }                return drawable ;    }            class Button2Lislen implements OnClickListener    {     @Override     public void onClick(View v)      {             new DownloadImageTask().execute(IMAGE_URL2) ;          }        }        private class DownloadImageTask extends AsyncTask
     
           {        /** The system calls this to perform work in a worker thread and          * delivers it the parameters given to AsyncTask.execute() */        protected Drawable doInBackground(String... urls) {            return loadImageFromNetwork(urls[0]);        }                /** The system calls this to perform work in the UI thread and delivers          * the result from doInBackground() */        protected void onPostExecute(Drawable result) {            mImageView.setImageDrawable(result);        }    }    //to see if these is a  network    public boolean isNetworkAvailable(Activity activity)    {        Context context = activity.getApplicationContext();        // 获取手机所有连接管理对象（包括对wi-fi,net等连接的管理）        ConnectivityManager connectivityManager = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);                if (connectivityManager == null)        {            return false;        }        else        {            // 获取NetworkInfo对象            NetworkInfo[] networkInfo = connectivityManager.getAllNetworkInfo();                        if (networkInfo != null && networkInfo.length > 0)            {                for (int i = 0; i < networkInfo.length; i++)                {                    System.out.println(i + "===状态===" + networkInfo[i].getState());                    System.out.println(i + "===类型===" + networkInfo[i].getTypeName());                    mTextView.setText("===网络状态===>" + networkInfo[i].getState()+"\n"+                            "===网络类型===>" + networkInfo[i].getTypeName());                   //Toast.makeText(MainActivity.this, "===状态===" + networkInfo[i].getState()+networkInfo[i].getTypeName(), 3000).show();                    // 判断当前网络状态是否为连接状态                    if (networkInfo[i].getState() == NetworkInfo.State.CONNECTED)                    {//                        mTextView.setText("===网络状态===>" + networkInfo[i].getState()+"\n"+//                                "===网络类型===>" + networkInfo[i].getTypeName());                        return true;                    }//                    mTextView.setText("===状态===>" + networkInfo[i].getState()+"\n"+//                                       "===类型===>" + networkInfo[i].getTypeName());                }            }        }        return false;    }                 }
     

 

权限：

manifest

效果 :