1）只显示网络图片

b)MainActivity.java

package dujun.king.urlgetimage;import java.io.InputStream;import java.net.URL;import android.app.Activity;import android.graphics.BitMap;import android.graphics.BitmapFactory;import android.os.Bundle;import android.os.Handler;import android.os.Message;import android.view.Menu;import android.view.MenuItem;import android.widget.ImageView;public class MainActivity extends Activity {        Bitmap bitmap;    ImageView imageview;        Handler handler=new Handler(){        @Override        public void handleMessage(Message msg) {            if (msg.what==0x9527) {                //显示从网上下载的图片                    imageview.setImageBitmap(bitmap);            }        }              };        @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        imageview=(ImageView)findViewById(R.id.imageView1);             //创建并启动一个新线程用于从网络上下载图片        new Thread(){            @Override            public void run() {                try {                    //创建一个url对象                    URL url=new URL("http://www.baidu.com/img/bdlogo.png");                    //打开URL对应的资源输入流                    InputStream is= url.openStream();                    //从InputStream流中解析出图片                    bitmap = BitmapFactory.decodeStream(is);                //  imageview.setImageBitmap(bitmap);                     //发送消息，通知UI组件显示图片                    handler.sendEmptyMessage(0x9527);                    //关闭输入流                    is.close();                } catch (Exception e) {                    e.printStackTrace();                }            }                  }.start();        }    @Override    public boolean onCreateOptionsMenu(Menu menu) {        // Inflate the menu; this adds items to the action bar if it is present.        getMenuInflater().inflate(R.menu.main, menu);        return true;    }    @Override    public boolean onOptionsItemSelected(MenuItem item) {        // Handle action bar item clicks here. The action bar will        // automatically handle clicks on the Home/Up Button, so long        // as you specify a parent activity in AndroidManifest.xml.        int id = item.getItemId();        if (id == R.id.action_settings) {            return true;        }        return super.onOptionsItemSelected(item);    }}

c）AndroidMainifest.xml  

2）如果我们要显示并下载网络图片，只需要将MainActivity.java文件修改如下： 

package dujun.king.urlgetimage;import java.io.InputStream;import java.io.OutputStream;import java.net.URL;import android.app.Activity;import android.graphics.Bitmap;import android.graphics.BitmapFactory;import android.os.Bundle;import android.os.Handler;import android.os.Message;import android.view.Menu;import android.view.MenuItem;import android.widget.ImageView;public class MainActivity extends Activity {        Bitmap bitmap;    ImageView imageview;        Handler handler=new Handler(){        @Override        public void handleMessage(Message msg) {            if (msg.what==0x9527) {                //显示从网上下载的图片                    imageview.setImageBitmap(bitmap);            }        }              };        @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        imageview=(ImageView)findViewById(R.id.imageView1);             //创建并启动一个新线程用于从网络上下载图片        //这里必须新起一个线程，Android后面的版本中，不允许在主线程中联网        new Thread(){            @Override            public void run() {                try {                    //创建一个url对象                    URL url=new URL("http://www.baidu.com/img/bdlogo.png");                    //打开URL对应的资源输入流                    InputStream is= url.openStream();                    //从InputStream流中解析出图片                    bitmap = BitmapFactory.decodeStream(is);                //  imageview.setImageBitmap(bitmap);                     //发送消息，通知UI组件显示图片                    handler.sendEmptyMessage(0x9527);                    //关闭输入流                    is.close();                    //------------------------------                    //下载网络图片                    //再次打开资源流                    is = url.openStream();                    //打开手机对应的输出流                    //存放在手机中，并命名为baidulogo.png                    OutputStream os = openFileOutput("baidulogo.png", MODE_WORLD_READABLE);                    byte[] buff = new byte[1024];                    int len = 0;                    //因为网络下载一般不可能一次下载完毕，我们将每次下载好的有效数据写入                    while ((len = is.read(buff)) > 0)                    {                            os.write(buff,0,len);                    }                    //关闭流                    is.close();                    os.close();                } catch (Exception e) {                    e.printStackTrace();                }            }                  }.start();    }    @Override    public boolean onCreateOptionsMenu(Menu menu) {        // Inflate the menu; this adds items to the action bar if it is present.        getMenuInflater().inflate(R.menu.main, menu);        return true;    }    @Override    public boolean onOptionsItemSelected(MenuItem item) {        // Handle action bar item clicks here. The action bar will        // automatically handle clicks on the Home/Up button, so long        // as you specify a parent activity in AndroidManifest.xml.        int id = item.getItemId();        if (id == R.id.action_settings) {            return true;        }        return super.onOptionsItemSelected(item);    }}