方便的方法来解析Servlet中传入的multipart / form-data参数 [英] Convenient way to parse incoming multipart/form-data parameters in a Servlet
问题描述
是否有任何方便的方法来读取和解析传入请求中的数据。
Is there any convenient way to read and parse data from incoming request.
例如客户发起帖子请求
URLConnection connection = new URL(url).openConnection();
connection.setDoOutput(true);
connection.setRequestProperty("Content-Type", "multipart/form-data; boundary=" + boundary);
PrintWriter writer = null;
try {
OutputStream output = connection.getOutputStream();
writer = new PrintWriter(new OutputStreamWriter(output, charset), true); // true = autoFlush, important!
// Send normal param.
writer.println("--" + boundary);
writer.println("Content-Disposition: form-data; name=\"param\"");
writer.println("Content-Type: text/plain; charset=" + charset);
writer.println();
writer.println(param);
我无法使用 request.getParameter（paramName获取参数）。以下代码
BufferedReader reader = new BufferedReader(new InputStreamReader(
request.getInputStream()));
StringBuilder sb = new StringBuilder();
for (String line; (line = reader.readLine()) != null;) {
System.out.println(line);
}
但显示我的内容
-----------------------------29772313742745
Content-Disposition: form-data; name="name"
J.Doe
-----------------------------29772313742745
Content-Disposition: form-data; name="email"
abuse@spamcop.com
-----------------------------29772313742745
解析传入请求的最佳方法是什么？我不想编写自己的解析器，可能有一个现成的解决方案。
What is the best way to parse incoming request? I don’t want to write my own parser, probably there is a ready solution.
推荐答案
multipart / form-data 版本3.0之前的Servlet API默认不支持编码请求。默认情况下，Servlet API使用 application / x-www-form-urlencoded 编码来解析参数。使用不同的编码时， request.getParameter（）调用都将返回 null 。当您已经使用Servlet 3.0（ Glassfish 3 ）时， Tomcat 7 等），然后你可以使用 HttpServletRequest＃getParts（） 。另请参阅此博客以获取扩展示例。
multipart/form-data encoded requests are indeed not by default supported by the Servlet API prior to version 3.0. The Servlet API parses the parameters by default using application/x-www-form-urlencoded encoding. When using a different encoding, the request.getParameter() calls will all return null. When you're already on Servlet 3.0 (Glassfish 3, Tomcat 7, etc), then you can use HttpServletRequest#getParts() instead. Also see this blog for extended examples.
在Servlet 3.0之前，事实上标准解析 multipart / form-data 请求将使用 Apache Commons FileUpload 。只需仔细阅读用户指南和常见问题部分，即可了解如何使用它。在此处之前，我已使用代码示例发布了答案（它还包含一个针对Servlet 3.0的示例。
Prior to Servlet 3.0, a de facto standard to parse multipart/form-data requests would be using Apache Commons FileUpload. Just carefully read its User Guide and Frequently Asked Questions sections to learn how to use it. I've posted an answer with a code example before here (it also contains an example targeting Servlet 3.0).
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