查看图片

效果图：

界面中有三个控件，一个EditText，一个Button，一个ImageView。

1.activity_main布局代码：

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

    <ImageView
        android:id="@+id/ivImage"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_weight="1"
        android:background="@drawable/back_button" />

    <Button
        android:id="@+id/btnView"
        android:layout_width="143dp"
        android:layout_height="wrap_content"
        android:onClick="showImage"
        android:paddingLeft="20px"
        android:layout_marginLeft="90px"
        android:text="浏览" />

    <EditText
        android:id="@+id/etImageUrl"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:ems="10"
        android:hint="http://pica.nipic.com/2007-11-09/2007119124513598_2.jpg"
         >

        <requestFocus />
    </EditText>

</LinearLayout>

2.MainActivity代码：

package com.example.chakan;

import android.os.Bundle;
import android.os.Handler;
import android.os.Looper;
import android.os.Message;

import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.text.TextUtils;
import android.util.Log;
import android.view.Menu;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ImageView;
import android.widget.Toast;
public class MainActivity extends Activity {
     private Button btn;
     private EditText path;
     private ImageView imgview;

     @Override
     protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_main);
      btn = (Button) findViewById(R.id.btnView);
      path = (EditText) findViewById(R.id.etImageUrl);
      imgview = (ImageView) findViewById(R.id.ivImage);

      btn.setKeyListener(new OnClickListener() {
       @Override
       public void onClick(View v) {
        Log.i("CLICK", ((Button) v).getText().toString());
        new Thread(runa).start();
       }
      });
     }

     public void setView() {
      String picturepath = path.getText().toString();
      byte[] data = null;
      try {
       data = ImageService.getImage(picturepath);
       Bitmap bitmap = BitmapFactory.decodeByteArray(data, 0, data.length);// BitmapFactory：图片工厂！
       Looper.prepare();// 必须调用此方法，要不然会报错
       Message msg = new Message();
       msg.what = 0;
       msg.obj = bitmap;
       handler.sendMessage(msg);
      } catch (Exception e) {
       Toast.makeText(getApplicationContext(), "获取图片错误", 1).show();
      }
     }

     private Handler handler = new Handler() {
      @Override
      public void handleMessage(Message msg) {
       if (msg.what == 0) {
        updateImageView((Bitmap) msg.obj);
       }
      }

     };

     private Runnable runa = new Runnable() {
      @Override
      public void run() {
       setView();
      }
     };

     private void updateImageView(Bitmap bm) {
      imgview.setImageBitmap(bm);
     }
    }

3.添加一个ImageService图片服务类，里面包含一个获取网络数据的方法；

package com.example.chakan;

import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;

public class ImageService {

     // 获取网络图片的数据
     public static byte[] getImage(String picturepath) throws Exception {
      URL url = new URL(picturepath);
      HttpURLConnection conn = (HttpURLConnection) url.openConnection();// 基于http协议的连接对象
      conn.setConnectTimeout(10);// 10秒；
      conn.setRequestMethod("GET");// 大写
      if (conn.getResponseCode() == 200) {
       InputStream ins = conn.getInputStream();
       return StreamTool.read(ins);
      }
      return null;
     }
}

4.添加一个流处理工作类StreamTool:

package com.example.chakan;

import java.io.ByteArrayOutputStream;
import java.io.InputStream;

public class StreamTool {

     public static byte[] read(InputStream ins) throws Exception {
      ByteArrayOutputStream outstream = new ByteArrayOutputStream();
      byte[] buffer = new byte[1024];
      int length = 0;
      while ((length = ins.read(buffer)) > -1) {
       outstream.write(buffer, 0, length);
      }
      outstream.close();
      return outstream.toByteArray();
     }
    }

到此，程序已经完全编写完毕。一定要注意在androidManifest中必须有配置文件，注意线程的使用。