如何在 Tomcat 上运行的 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 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

为了得到 HttpServletRequest#getParts() 在 Filter 在Tomcat中，需要设置allowCasualMultipartParsing="true" 在 webapp 的 Webapp/META-INF/context.xml 或 Tomcat/conf/server.xml 中的 a> 元素.

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">

因为根据 servlet 3.0 规范 HttpServletRequest#getParts() 应该只在 HttpServlet 和 @MultipartConfig 注释.另请参阅 的文档 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:

设置为true，如果HttpServletRequest.getPart* 或HttpServletRequest 时Tomcat 应该自动解析multipart/form-data 请求体.getParameter* 被调用，即使目标 servlet 没有用 @MultipartConfig 注释标记(有关详细信息，请参阅 Servlet 规范 3.0，第 3.2 节).请注意，除 false 之外的任何设置都会导致 Tomcat 以不符合技术规范的方式运行.默认为 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

与具体问题无关，以下肯定是不对的:

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

首先，您没有遵守客户端指定的字符编码 - 如果有的话.其次，这对于二进制文件会失败.

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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