base64 编解码Cookie 图片

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<%@ page language="java" pageEncoding="UTF-8" %>
<jsp:directive.page import="sun.misc.BASE64Encoder"/>
<jsp:directive.page import="java.io.InputStream"/>
<jsp:directive.page import="java.io.File"/>
<%
File file = new File(this.getServletContext().getRealPath("cookie.gif"));

// 二进制数组
byte[] binary = new byte[(int)file.length()];

// 从图片文件读取二进制数据.
InputStream ins = this.getServletContext().getResourceAsStream(file.getName());
ins.read(binary);
ins.close();

// BASE64 编码
String content = BASE64Encoder.class.newInstance().encode(binary);

// 包含二进制数据的 Cookie
Cookie cookie = new Cookie("file", content);

// 将 Cookie 发送到客户端
response.addCookie(cookie);
%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>Cookie Encoding</title>
</head>
<body>
从 Cookie 中获取到的二进制图片：<img src="base64_decode.jsp" /> <br/>
<textarea id='cookieArea' style='width:100%; height:200px; '></textarea>
<script type="text/javascript">cookieArea.value=document.cookie;</script>
</body>
</html>

<%@ page language="java" pageEncoding="UTF-8" %>
<jsp:directive.page import="sun.misc.BASE64Decoder"/>
<jsp:directive.page trimDirectiveWhitespaces="true"/>
<%
// 清除输出
out.clear();

for(Cookie cookie : request.getCookies()){

  if(cookie.getName().equals("file")){

   // 从 Cookie 中取二进制数据
   byte[] binary = BASE64Decoder.class.newInstance().decodeBuffer(cookie.getValue().replace(" ", ""));

   // 设置内容类型为 gif 图片
   response.setHeader("Content-Type", "image/gif");
   response.setHeader("Content-Disposition", "inline;filename=cookie.gif");
   response.setHeader("Connection", "close");

   // 设置长度
   response.setContentLength(binary.length);

   // 输出到客户端
   response.getOutputStream().write(binary);
   response.getOutputStream().flush();
   response.getOutputStream().close();

   return;
  }
}

%>

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