java - 如何在Struts 2中上传多个文件

Question

我有一个 JavaScript，可以将文件多次上传到我的画廊系统。

当按钮start upload时单击后，它会在 Action 中调用我的方法的多个线程Struts 2 类。

在此方法中，我需要验证我的图库系统是否有空间来接受文件(为此，我使用业务对象，然后使用 DAO 类)。

但我的问题是:

当我这样做时，我的操作线程几乎同时执行验证，但如果线程没有完成上传，那么其他线程的大小就会不正确。

如何在Struts 2中进行多个文件上传？

Answer 1

The Struts 2 framework provides built-in support for processing file uploads that conform to RFC 1867.

您不需要使用多个请求/线程来上传多个文件。每个请求都作为单个文件上传进行处理，同时使用 Web 服务器的线程池。服务器为来自任何客户端的每个请求选择一个线程。因此，如果您通过单个文件上传来上传多个文件，您将无法控制处理所有文件所需的空间。任何单个文件上传都可能因系统无法接受该文件而失败，并且与特定客户端无关。

如果您需要一次上传所有多个文件，那么您应该使用 Multiple File Uploading .

As mentioned in the previous section one technique for uploading multiple files would be to simply have multiple form input elements of type file all with different names. This would require a number of setter methods that was equal to 3 times the number of files being uploaded. Another option is to use Arrays or java.util.Lists.

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您可以配置fileUpload interceptor限制上传文件的大小

maximumSize (optional) - the maximum size (in bytes) that the interceptor will allow a file reference to be set on the action. Note, this is not related to the various properties found in struts.properties. Default to approximately 2MB.

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然后您可以配置从拦截器返回的自定义消息。

This interceptor will add several field errors, assuming that the action implements ValidationAware. These error messages are based on several i18n values stored in struts-messages.properties, a default i18n file processed for all i18n requests. You can override the text of these messages by providing text for the following keys:

• struts.messages.error.uploading - a general error that occurs when the file could not be uploaded

• struts.messages.error.file.too.large - occurs when the uploaded file is too large

• struts.messages.error.content.type.not.allowed - occurs when the uploaded file does not match the expected content types specified

• struts.messages.error.file.extension.not.allowed - occurs when the uploaded file does not match the expected file extensions specified

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单个请求上传多个文件。要控制请求的总大小，您可以使用常量或属性struts.multipart.maxSize。例如，常量将每个请求的限制设置为 1M。

<constant name="struts.multipart.maxSize" value="1000000" />

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