Android从网络中获得一张图片并显示在屏幕上的实例详解

<?xml version="1.0" encoding="utf-8"?> 
<manifest xmlns:android="http://schemas.android.com/apk/res/android" 
   package="cn.capinftotech.image" 
   android:versioncode="1" 
   android:versionname="1.0"> 
  <application android:icon="@drawable/icon" android:label="@string/app_name"> 
    <activity android:name=".mainactivity" 
         android:label="@string/app_name"> 
      <intent-filter> 
        <action android:name="android.intent.action.main" /> 
        <category android:name="android.intent.category.launcher" /> 
      </intent-filter> 
    </activity> 
 
  </application> 
  <uses-sdk android:minsdkversion="8" /> 
  <uses-permission android:name="android.permission.internet" /> 
 
</manifest>  

package cn.capinftotech.image; 
 
import java.io.ioexception; 
 
import android.app.activity; 
import android.graphics.bitmap; 
import android.graphics.bitmapfactory; 
import android.os.bundle; 
import android.util.log; 
import android.view.view; 
import android.widget.button; 
import android.widget.edittext; 
import android.widget.imageview; 
import android.widget.toast; 
 
import com.capinfotech.service.imageservice; 
 
public class mainactivity extends activity { 
  private static final string tag = "mainactivity"; 
   
  private edittext urlpath = null; 
  private button button = null; 
  private imageview imageview = null; 
   
  @override 
  public void oncreate(bundle savedinstancestate) { 
    super.oncreate(savedinstancestate); 
    setcontentview(r.layout.main); 
     
    urlpath = (edittext)findviewbyid(r.id.urlpath); 
    button = (button)findviewbyid(r.id.button); 
    imageview = (imageview)findviewbyid(r.id.imageview); 
     
    button.setonclicklistener(new view.onclicklistener() { 
       
      @override 
      public void onclick(view v) { 
        string urlpathcontent = urlpath.gettext().tostring(); 
        try { 
          byte[] data = imageservice.getimage(urlpathcontent); 
          bitmap bitmap = bitmapfactory.decodebytearray(data, 0, data.length); //生成位图 
          imageview.setimagebitmap(bitmap);  //显示图片 
        } catch (ioexception e) { 
          toast.maketext(mainactivity.this, r.string.error, toast.length_long).show(); //通知用户连接超时信息 
          log.i(tag, e.tostring()); 
        } 
         
      } 
    }); 
  } 
} 

package com.capinfotech.service; 
 
import java.io.ioexception; 
import java.io.inputstream; 
import java.net.httpurlconnection; 
import java.net.url; 
 
import com.capinfotech.utils.streamtool; 
 
public class imageservice { 
   
  public static byte[] getimage(string path) throws ioexception { 
    url url = new url(path); 
    httpurlconnection conn = (httpurlconnection)url.openconnection(); 
    conn.setrequestmethod("get");  //设置请求方法为get 
    conn.setreadtimeout(5*1000);  //设置请求过时时间为5秒 
    inputstream inputstream = conn.getinputstream();  //通过输入流获得图片数据 
    byte[] data = streamtool.readinputstream(inputstream);   //获得图片的二进制数据 
    return data; 
     
  } 
} 

package com.capinfotech.utils; 
 
import java.io.bytearrayoutputstream; 
import java.io.ioexception; 
import java.io.inputstream; 
 
public class streamtool { 
 
  /* 
   * 从数据流中获得数据 
   */ 
  public static byte[] readinputstream(inputstream inputstream) throws ioexception { 
    byte[] buffer = new byte[1024]; 
    int len = 0; 
    bytearrayoutputstream bos = new bytearrayoutputstream(); 
    while((len = inputstream.read(buffer)) != -1) { 
      bos.write(buffer, 0, len); 
    } 
    bos.close(); 
    return bos.tobytearray(); 
     
  } 
} 

<?xml version="1.0" encoding="utf-8"?> 
<resources> 
  <string name="hello">hello world, mainactivity!</string> 
  <string name="app_name">图片浏览器</string> 
  <string name="urlpath">网络图片地址</string> 
  <string name="button">显示</string> 
  <string name="error">网络连接超时</string> 
</resources> 

<?xml version="1.0" encoding="utf-8"?> 
<linearlayout xmlns:android="http://schemas.android.com/apk/res/android" 
  android:orientation="vertical" 
  android:layout_width="fill_parent" 
  android:layout_height="fill_parent" 
  > 
<textview  
  android:layout_width="fill_parent"  
  android:layout_height="wrap_content"  
  android:text="@string/urlpath" 
  /> 
<edittext  
  android:id="@+id/urlpath" 
  android:layout_width="fill_parent"  
  android:layout_height="wrap_content"  
  android:text="http://www.eoeandroid.com/data/attachment/forum/201107/18/142935bbi8d3zpf3d0dd7z.jpg" 
  /> 
<button 
  android:id="@+id/button" 
  android:layout_width="wrap_content"  
  android:layout_height="wrap_content"  
  android:text="@string/button" 
  /> 
<imageview 
  android:id="@+id/imageview" 
  android:layout_width="wrap_content"  
  android:layout_height="wrap_content"  
/> 
</linearlayout>