正则表达式提取html图片地址

public static String getImgStr(String htmlStr){  
        String img="",tmp="";  
        java.util.regex.Pattern p_image;  
        java.util.regex.Matcher m_image;  
          
        String regEx_img = "http://[([a-z0-9]|.|/|//-)]+.[(jpg)|(bmp)|(gif)|(png)]";//图片链接地址  
        p_image = java.util.regex.Pattern.compile(regEx_img,java.util.regex.Pattern.CASE_INSENSITIVE);  
        m_image = p_image.matcher(htmlStr);  
        while(m_image.find()){  
            img = img + "," + m_image.group();  
        }  
        if(img.indexOf(",")>=0)  
            return img.substring(1);  
        else 
            return img;  
   }