如何在运行在Tomcat上的Servlet过滤器中使用HttpServletRequest＃getParts（）？ [英] How to use HttpServletRequest#getParts() in a servlet filter running on Tomcat?

问题描述

我想在我的JSF应用程序中上传一个文件。我正在使用 Filter 和 HttpServletRequestWrapper 来访问上传文件。

I would like to upload a file in my JSF application. I am using a Filter and HttpServletRequestWrapper to access the upload file.

 public MultipartRequestWrapper(HttpServletRequest request) {
    super(request);
    System.out.println("Created multipart wrapper....");
    try {
        System.out.println("Looping parts"+getParts().size());

        for (Part p : getParts()) {
            System.out.println(String.format("Part name: %1$s, contentType : %2$s", p.getName(), p.getContentType()));
            for(String header : p.getHeaderNames()){
                System.out.println("Header name : " + header + ", value : " + p.getHeader(header));
            }
            byte[] b = new byte[(int) p.getSize()];
            p.getInputStream().read(b);
            params.put(p.getName(), new String[]{new String(b)});
        }
    } catch (IOException ex) {
        ex.printStackTrace();
        Logger.getLogger(MultipartRequestWrapper.class.getName()).log(Level.SEVERE, null, ex);
    } catch (ServletException ex) {
         ex.printStackTrace();
        Logger.getLogger(MultipartRequestWrapper.class.getName()).log(Level.SEVERE, null, ex);
    }

然而， getParts（）返回一个空集合。如何在Tomcat 7.0.8中的servlet过滤器中启用 multipart / form-data 解析

However, getParts() returns an empty collection. How can I enable multipart/form-data parsing in a servlet filter in Tomcat 7.0.8?

推荐答案

为了获得 HttpServletRequest＃getParts（） 可以在 Filter 在Tomcat中，您需要设置 allowCasualMultipartParsing =在web应用程序的 中，输入true在 Webapp / META-INF / context.xml 或 Tomcat / conf中的< Context> /server.xml 。
$ b

In order to get HttpServletRequest#getParts() to work in a Filter in Tomcat, you need to set allowCasualMultipartParsing="true" in the webapp's <Context> element in Webapp/META-INF/context.xml or Tomcat/conf/server.xml.

<Context ... allowCasualMultipartParsing="true">

因为按照servlet 3.0规范 HttpServletRequest＃getParts（） a>只能在 HttpServlet 与 @MultipartConfig 注释。另请参阅 < Context> 元素：

Because as per the servlet 3.0 specification the HttpServletRequest#getParts() should only be available inside a HttpServlet with the @MultipartConfig annotation. See also the documentation of the <Context> element:

allowCasualMultipartParsing

设置为 true 如果Tomcat应该自动解析 multipart / form-data HttpServletRequest.getPart * 或 HttpServletRequest.getParameter * t用 @MultipartConfig 注释标记（详情参见Servlet Specification 3.0，Section 3.2）。请注意，除 false 之外的任何设置都会导致Tomcat的行为方式不符合技术规范。默认是 false 。

allowCasualMultipartParsing

Set to true if Tomcat should automatically parse multipart/form-data request bodies when HttpServletRequest.getPart* or HttpServletRequest.getParameter* is called, even when the target servlet isn't marked with the @MultipartConfig annotation (See Servlet Specification 3.0, Section 3.2 for details). Note that any setting other than false causes Tomcat to behave in a way that is not technically spec-compliant. The default is false.

另见：

• Tomcat 7问题49711


• 在Servlet 3.0中上传文件


• 在JSF 2.0和Servlet 3.0中上传文件



See also:

• Tomcat 7 issue 49711
• Uploading files in Servlet 3.0
• Uploading files in JSF 2.0 and Servlet 3.0

无关具体问题，以下绝对不对：



Unrelated to the concrete problem, the following is definitely not right:

byte[] b = new byte[(int) p.getSize()];
p.getInputStream().read(b);
params.put(p.getName(), new String[]{new String(b)});

首先，您不尊重客户端指定的字符编码-if any。其次，二进制文件会失败。

First, you are not respecting the character encoding specified by the client -if any. Second, this will fail for binary files.

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