用Data Url (data:image/jpg;base64,)将小图片生成数据流形式

<img src="data:image/jpg;base64,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" />

  就是一张图片的Data URL,利用base64编码把图片数据翻译成标准ASCII字符。

 相当于

<img src="http://www.oschina.net/img/logo_s2.png"/>

Data URL是在本地直接绘制图片，不是从服务器加载，所以节省了HTTP连接，起到加速网页的作用。
data:image/jpg;    声明数据协议及类型名称
base64,               编码形式为base64
/9j/4AAQSkZ……    base64编码结果

用base64转图片：http://base64.xpcha.com/pic.html

java实现图片与base64字符串之间的转换：

1. import java.io.FileInputStream;  
2. import java.io.FileOutputStream;  
3. import java.io.IOException;  
4. import java.io.InputStream;  
5. import java.io.OutputStream;  
6.   
7. import sun.misc.BASE64Decoder;  
8. import sun.misc.BASE64Encoder;  
9.   
10. public class Base64Test   
11. {  
12.     public static void main(String[] args)  
13.     {  
14.         String strImg = GetImageStr();  
15.         System.out.println(strImg);  
16.         GenerateImage(strImg);  
17.     }  
18.     //图片转化成base64字符串  
19.     public static String GetImageStr()  
20.     {//将图片文件转化为字节数组字符串，并对其进行Base64编码处理  
21.         String imgFile = "d://test.jpg";//待处理的图片  
22.         InputStream in = null;  
23.         byte[] data = null;  
24.         //读取图片字节数组  
25.         try   
26.         {  
27.             in = new FileInputStream(imgFile);          
28.             data = new byte[in.available()];  
29.             in.read(data);  
30.             in.close();  
31.         }   
32.         catch (IOException e)   
33.         {  
34.             e.printStackTrace();  
35.         }  
36.         //对字节数组Base64编码  
37.         BASE64Encoder encoder = new BASE64Encoder();  
38.         return encoder.encode(data);//返回Base64编码过的字节数组字符串  
39.     }  
40.       
41.     //base64字符串转化成图片  
42.     public static boolean GenerateImage(String imgStr)  
43.     {   //对字节数组字符串进行Base64解码并生成图片  
44.         if (imgStr == null) //图像数据为空  
45.             return false;  
46.         BASE64Decoder decoder = new BASE64Decoder();  
47.         try   
48.         {  
49.             //Base64解码  
50.             byte[] b = decoder.decodeBuffer(imgStr);  
51.             for(int i=0;i<b.length;++i)  
52.             {  
53.                 if(b[i]<0)  
54.                 {//调整异常数据  
55.                     b[i]+=256;  
56.                 }  
57.             }  
58.             //生成jpeg图片  
59.             String imgFilePath = "d://222.jpg";//新生成的图片  
60.             OutputStream out = new FileOutputStream(imgFilePath);      
61.             out.write(b);  
62.             out.flush();  
63.             out.close();  
64.             return true;  
65.         }   
66.         catch (Exception e)   
67.         {  
68.             return false;  
69.         }  
70.     }  
71. }