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new e59291b Cleans up file upload documentation
e59291b is described below
commit e59291b0ff69cf96f57f04918284cb931753d8da
Author: Lukasz Lenart <[email protected]>
AuthorDate: Wed Nov 14 07:52:56 2018 +0100
Cleans up file upload documentation
---
source/core-developers/file-upload.md | 203 +++++++++++++++++-----------------
1 file changed, 104 insertions(+), 99 deletions(-)
diff --git a/source/core-developers/file-upload.md
b/source/core-developers/file-upload.md
index c6ae227..fddca06 100644
--- a/source/core-developers/file-upload.md
+++ b/source/core-developers/file-upload.md
@@ -4,23 +4,32 @@ title: File Upload
---
# File Upload
+{:.no_toc}
-The Struts 2 framework provides built\-in support for processing file uploads
that conform to [RFC
1867](http://www\.ietf\.org/rfc/rfc1867\.txt)^[http://www\.ietf\.org/rfc/rfc1867\.txt],
"Form\-based File Upload in HTML"\. When correctly configured the framework
will pass uploaded file(s) into your Action class\. Support for individual and
multiple file uploads are provided\. When a file is uploaded it will typically
be stored in a temporary directory\. Uploaded files should be processed [...]
+* Will be replaced with the ToC, excluding a header
+{:toc}
+
+The Struts 2 framework provides built-in support for processing file uploads
that conform to [RFC 1867](http://www.ietf.org/rfc/rfc1867.txt),
+"Form-based File Upload in HTML". When correctly configured the framework will
pass uploaded file(s) into your Action class.
+Support for individual and multiple file uploads are provided. When a file is
uploaded it will typically be stored in a temporary directory.
+Uploaded files should be processed or moved by your Action class to ensure the
data is not lost. Be aware that servers may have a security
+policy in place that prohibits you from writing to directories other than the
temporary directory and the directories that belong to your
+web application.
## Dependencies
-The Struts 2 framework leverages add\-on libraries to handle the parsing of
uploaded files\. These libraries are not included in the Struts distribution,
you must add them into your project\. The libraries needed are:
+The Struts 2 framework leverages add-on libraries to handle the parsing of
uploaded files. These libraries are not included in the Struts
+distribution, you must add them into your project. The libraries needed are:
-|Library|URL|Struts 2\.0\.x|Struts 2\.1\.x|Struts 2\.5\.x|
+|Library|URL|Struts 2.0.x|Struts 2.1.x|Struts 2.5.x|
|-------|---|--------------|--------------|--------------|
-|Commons\-FileUpload|[http://commons\.apache\.org/fileupload/](http://commons\.apache\.org/fileupload/)|1\.1\.1|1\.2\.1|1\.3\.2|
-|Commons\-IO|[http://commons\.apache\.org/io/](http://commons\.apache\.org/io/)|1\.0|1\.3\.2|2\.4|
-
-If you are using Maven then you can add these libraries as dependencies in
your project's pom\.xml\.
+|Commons-FileUpload|[http://commons.apache.org/fileupload/](http://commons.apache.org/fileupload/)|1.1.1|1.2.1|1.3.2|
+|Commons-IO|[http://commons.apache.org/io/](http://commons.apache.org/io/)|1.0|1.3.2|2.4|
-**Struts 2\.0\.x File Upload Dependencies**
+If you are using Maven then you can add these libraries as dependencies in
your project's pom.xml.
+### Struts 2.0.x File Upload Dependencies
```xml
<dependency>
@@ -33,11 +42,9 @@ If you are using Maven then you can add these libraries as
dependencies in your
<artifactId>commons-io</artifactId>
<version>1.0</version>
</dependency>
-
```
-**Struts 2\.1\.x File Upload Dependencies**
-
+### Struts 2.1.x File Upload Dependencies
```xml
<dependency>
@@ -50,15 +57,15 @@ If you are using Maven then you can add these libraries as
dependencies in your
<artifactId>commons-io</artifactId>
<version>1.3.2</version>
</dependency>
-
```
## Basic Usage
-The `org.apache.struts2.interceptor.FileUploadInterceptor` class is included
as part of the `defaultStack`\. As long as the required libraries are added to
your project you will be able to take advantage of of the Struts 2 fileUpload
capability\. Configure an Action mapping for your Action class as you typically
would\.
-
-**Example action mapping:**
+The `org.apache.struts2.interceptor.FileUploadInterceptor` class is included
as part of the `defaultStack`. As long as the required libraries
+are added to your project you will be able to take advantage of of the Struts
2 fileUpload capability. Configure an Action mapping for your
+Action class as you typically would.
+### Example action mapping:
```xml
<action name="doUpload" class="com.example.UploadAction">
@@ -67,26 +74,23 @@ The `org.apache.struts2.interceptor.FileUploadInterceptor`
class is included as
```
-A form must be create with a form field of type file, `<INPUT type="file"
name="upload">`\. The form used to upload the file must have its encoding type
set to multipart/form\-data,
-`<FORM action="doUpload" enctype="multipart/form-data" method="post">`\. The
standard procedure for adding these elements is by using the Struts 2 tag
libraries as shown in the following example:
-
-**Example JSP form tags:**
+A form must be create with a form field of type file, `<INPUT type="file"
name="upload">`. The form used to upload the file must have its
+encoding type set to `multipart/form-data`, `<form action="doUpload"
enctype="multipart/form-data" method="post">`. The standard procedure
+for adding these elements is by using the Struts 2 tag libraries as shown in
the following example:
-{% comment %}start snippet
id=example-form|lang=xml|javadoc=true|url=org.apache.struts2.interceptor.FileUploadInterceptor
{% endcomment %}
+### Example JSP form tags:
```xml
<s:form action="doUpload" method="post" enctype="multipart/form-data">
<s:file name="upload" label="File"/>
<s:submit/>
</s:form>
-
```
-{% comment %}end snippet
id=example-form|lang=xml|javadoc=true|url=org.apache.struts2.interceptor.FileUploadInterceptor
{% endcomment %}
-The fileUpload interceptor will use setter injection to insert the uploaded
file and related data into your Action class\. For a form field named
**upload** you would provide the three setter methods shown in the following
example:
-
-**Example Action class:**
+The fileUpload interceptor will use setter injection to insert the uploaded
file and related data into your Action class. For a form field
+named `upload` you would provide the three setter methods shown in the
following example:
+### Example Action class:
```java
package com.example;
@@ -119,22 +123,26 @@ package com.example;
```
-The purpose of each one of these methods is described in the table below\.
Notice that if you have multiple file form elements with different names you
would be required to have another corresponding set of these methods for each
file uploaded\.
+The purpose of each one of these methods is described in the table below.
Notice that if you have multiple file form elements with different
+names you would be required to have another corresponding set of these methods
for each file uploaded.
|Method Signature|Description|
|----------------|-----------|
-|setX(File file)|The file that contains the content of the uploaded file\.
This is a temporary file and file\.getName() will not return the original name
of the file|
-|setXContentType(String contentType)|The mime type of the uploaded file|
-|setXFileName(String fileName)|The actual file name of the uploaded file (not
the HTML name)|
+|`setX(File file)`|The file that contains the content of the uploaded file.
This is a temporary file and file.getName() will not return the original name
of the file|
+|`setXContentType(String contentType)`|The mime type of the uploaded file|
+|`setXFileName(String fileName)`|The actual file name of the uploaded file
(not the HTML name)|
## Uploading Multiple Files
-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\. The following examples are taken from the
Showcase example application that is part sample applications you can download
at [http://struts\.apache\.org/dow [...]
-
-__Uploading Multiple Files using Arrays__
+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. The following examples are
taken from the Showcase example application that is part
+sample applications you can download at
[http://struts.apache.org/download.cgi](http://struts.apache.org/download.cgi).
For the Action mapping
+details see `struts-fileupload.xml` in the sample application download.
-**multipleUploadUsingArray\.jsp** Notice all file input types have the same
name\.
+### Uploading Multiple Files using Arrays
+`multipleUploadUsingArray.jsp` Notice all file input types have the same name.
```jsp
<s:form action="doMultipleUploadUsingArray" method="POST"
enctype="multipart/form-data">
@@ -145,13 +153,7 @@ __Uploading Multiple Files using Arrays__
</s:form>
```
-**MultipleFileUploadUsingArrayAction\.java**
-
-
-
-**
-**
-
+`MultipleFileUploadUsingArrayAction.java`
```java
public class MultipleFileUploadUsingArrayAction extends ActionSupport {
@@ -197,12 +199,9 @@ public class MultipleFileUploadUsingArrayAction extends
ActionSupport {
}
```
-
-
-__Uploading Multiple Files using Lists__
-
-**multipleUploadUsingList\.jsp** Notice all file input types have the same
name\.
+### Uploading Multiple Files using Lists
+`multipleUploadUsingList.jsp` Notice all file input types have the same name.
```jsp
<s:form action="doMultipleUploadUsingList" method="POST"
enctype="multipart/form-data">
@@ -213,8 +212,7 @@ __Uploading Multiple Files using Lists__
</s:form>
```
-**MultipleFileUploadUsingListAction\.java**
-
+`MultipleFileUploadUsingListAction.java`
```java
public class MultipleFileUploadUsingListAction extends ActionSupport {
@@ -262,25 +260,20 @@ public class MultipleFileUploadUsingListAction extends
ActionSupport {
## Advanced Configuration
-The Struts 2 `default.properties` file defines several settings that affect
the behavior of file uploading\. You may find in necessary to change these
values\. The names and default values are:
-
+The Struts 2 `default.properties` file defines several settings that affect
the behavior of file uploading. You may find in necessary
+to change these values. The names and default values are:
-~~~~~~~
+```
struts.multipart.parser=jakarta
struts.multipart.saveDir=
struts.multipart.maxSize=2097152
+```
-~~~~~~~
-
-
-
-| Please remember that the **struts\.multipart\.maxSize** is the size limit of
the whole request, which means when you uploading multiple files, the sum of
their size must be below the **struts\.multipart\.maxSize**\!
-
-|
+> Please remember that the `struts.multipart.maxSize` is the size limit of the
whole request, which means when you uploading multiple files,
+> the sum of their size must be below the `struts.multipart.maxSize`!
In order to change theses settings you define a constant in your applications
`struts.xml` file like so:
-
```xml
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE struts PUBLIC
@@ -290,11 +283,9 @@ In order to change theses settings you define a constant
in your applications `s
<constant name="struts.multipart.maxSize" value="1000000" />
...
</struts>
-
```
-Additionally the `fileUpload` interceptor has settings that can be put in
place for individual action mappings by customizing your interceptor stack\.
-
+Additionally the `fileUpload` interceptor has settings that can be put in
place for individual action mappings by customizing your interceptor stack.
```xml
<action name="doUpload" class="com.example.UploadAction">
@@ -307,14 +298,16 @@ Additionally the `fileUpload` interceptor has settings
that can be put in place
<result name="success">good_result.jsp</result>
</action>
-
```
-__File Size Limits__
-
-There are two separate file size limits\. First is `struts.multipart.maxSize`
which comes from the Struts 2 `default.properties` file\. This setting exists
for security reasons to prohibit a malicious user from uploading extremely
large files to file up your servers disk space\. This setting defaults to
approximately 2 megabytes and should be adjusted to the maximum size file (2
gigs max) that your will need the framework to receive\. If you are uploading
more than one file on a form the [...]
-`maximumSize`, is an interceptor setting that is used to ensure a particular
Action does not receive a file that is too large\. Notice the locations of both
settings in the following example:
+### File Size Limits
+There are two separate file size limits. First is `struts.multipart.maxSize`
which comes from the Struts 2 `default.properties` file.
+This setting exists for security reasons to prohibit a malicious user from
uploading extremely large files to file up your servers disk space.
+This setting defaults to approximately 2 megabytes and should be adjusted to
the maximum size file (2 gigs max) that your will need the framework
+to receive. If you are uploading more than one file on a form the
`struts.multipart.maxSize` applies to the combined total, not the individual
+file sizes. The other setting, `maximumSize`, is an interceptor setting that
is used to ensure a particular Action does not receive a file
+that is too large. Notice the locations of both settings in the following
example:
```xml
<?xml version="1.0" encoding="UTF-8"?>
@@ -338,10 +331,10 @@ There are two separate file size limits\. First is
`struts.multipart.maxSize` wh
```
-__File Types__
-
-There are two ways to limit the uploaded file type, declaratively and
programmatically\. To declaratively limit the file type a comma separated list
of allowedTypes can be specified as a fileUpload interceptor param as shown in
the following example:
+### File Types
+There are two ways to limit the uploaded file type, decoratively and
programmatically. To decoratively limit the file type a comma separated
+list of allowedTypes can be specified as a fileUpload interceptor param as
shown in the following example:
```xml
<action name="doUpload" class="com.example.UploadAction">
@@ -354,60 +347,72 @@ There are two ways to limit the uploaded file type,
declaratively and programmat
<result name="success">good_result.jsp</result>
</action>
-
```
-When the uploaded file type does not match one of the MIME types specified a
field error will be created as described in the next section entitled Error
Messages\. Programmatically limiting the file type means using the information
passed in to your Action class via the `setXContentType(String contentType)`
method\. The benefit to this type of approach would be that it's more flexible
and no interceptor configuration would be needed if file sizes are keep under 2
megs\.
+When the uploaded file type does not match one of the MIME types specified a
field error will be created as described in the next section
+entitled Error Messages. Programmatically limiting the file type means using
the information passed in to your Action class via
+the `setXContentType(String contentType)` method. The benefit to this type of
approach would be that it's more flexible and no interceptor
+configuration would be needed if file sizes are keep under 2 megs.
-__Error Messages__
+### Error Messages
-If an error occurs several field errors will be added assuming that the action
implements `com.opensymphony.xwork2.ValidationAware` or extends
`com.opensymphony.xwork2.ActionSupport`\. 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:
+If an error occurs several field errors will be added assuming that the action
implements `com.opensymphony.xwork2.ValidationAware`
+or extends `com.opensymphony.xwork2.ActionSupport`. 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:
|Error Key|Description|
|---------|-----------|
-|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 as specified by maximumSize\.|
-|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 uploaded
file has disallowed extension|
-|struts\.messages\.upload\.error\.SizeLimitExceededException|Occurs when the
upload request (as a whole) exceed configured **struts\.multipart\.maxSize**|
-|struts\.messages\.upload\.error\.\<Exception class SimpleName\>|Occurs when
any other exception took place during file upload process|
+|`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 as specified by maximumSize.|
+|`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 uploaded file
has disallowed extension|
+|`struts.messages.upload.error.SizeLimitExceededException`|Occurs when the
upload request (as a whole) exceed configured **struts.multipart.maxSize**|
+|`struts.messages.upload.error.<Exception class SimpleName>`|Occurs when any
other exception took place during file upload process|
-__Temporary Directories__
+### Temporary Directories
-All uploaded files are saved to a temporary directory by the framework before
being passed in to an Action\. Depending on the allowed file sizes it may be
necessary to have the framework store these temporary files in an alternate
location\. To do this change `struts.multipart.saveDir` to the directory where
the uploaded files will be placed\. If this property is not set it defaults to
`javax.servlet.context.tempdir`\. Keep in mind that on some operating systems,
like Solaris, `/tmp` is [...]
+All uploaded files are saved to a temporary directory by the framework before
being passed in to an Action. Depending on the allowed file
+sizes it may be necessary to have the framework store these temporary files in
an alternate location. To do this change `struts.multipart.saveDir`
+to the directory where the uploaded files will be placed. If this property is
not set it defaults to `javax.servlet.context.tempdir`.
+Keep in mind that on some operating systems, like Solaris, `/tmp` is memory
based and files stored in that directory would consume
+an amount of RAM approximately equal to the size of the uploaded file.
-__Alternate Libraries__
+### Alternate Libraries
-The `struts.multipart.parser` used by the fileUpload interceptor to handle
HTTP POST requests, encoded using the MIME\-type multipart/form\-data, can be
changed out\. Currently there are two choices, jakarta and pell\. The jakarta
parser is a standard part of the Struts 2 framework needing only its required
libraries added to a project\. The pell parser uses Jason Pell's multipart
parser instead of the Commons\-FileUpload library\. The pell parser is a Struts
2 plugin, for more details s [...]
+The `struts.multipart.parser` used by the fileUpload interceptor to handle
HTTP POST requests, encoded using the MIME-type `multipart/form-data`,
+can be changed out. Currently there are two choices, jakarta and pell. The
jakarta parser is a standard part of the Struts 2 framework needing
+only its required libraries added to a project. The pell parser uses Jason
Pell's multipart parser instead of the Commons-FileUpload library.
+The pell parser is a Struts 2 plugin, for more details see: [Pell multipart
plugin](../plugins/pell/). There was a third alternative, cos, but it was
removed
+due to licensing incompatibilities.
-As from Struts version 2\.3\.18 a new implementation of `MultiPartRequest` was
added \- `JakartaStreamMultiPartRequest`\. It can be used to handle large
files, see
[WW\-3025](https://issues\.apache\.org/jira/browse/WW\-3025)^[https://issues\.apache\.org/jira/browse/WW\-3025]
for more details, but you can simple set
+As from Struts version 2.3.18 a new implementation of `MultiPartRequest` was
added - `JakartaStreamMultiPartRequest`. It can be used to handle
+large files, see [WW-3025](https://issues.apache.org/jira/browse/WW-3025) for
more details, but you can simple set
+```
+<constant name="struts.multipart.parser" value="jakarta-stream" />
+```
+in struts.xml to start using it.
-> \<constant name="struts\.multipart\.parser" value="jakarta\-stream" /\>
-
-in struts\.xml to start using it\.
-
-__Request validation__
-
-The `struts.multipart.validationRegex` is used to define a RegEx to be used to
validate if the incoming request is a multipart request\. The request must use
the `POST` method and match the RegEx, by default the RegEx is defined as
follow:
+### Request validation
+The `struts.multipart.validationRegex` is used to define a RegEx to be used to
validate if the incoming request is a multipart request.
+The request must use the `POST` method and match the RegEx, by default the
RegEx is defined as follow:
-~~~~~~~
+```
^multipart\\/form-data(; boundary=[a-zA-Z0-9]{1,70})?
-~~~~~~~
+```
-Please read
[RFC1341](https://www\.w3\.org/Protocols/rfc1341/7\_2\_Multipart\.html)^[https://www\.w3\.org/Protocols/rfc1341/7\_2\_Multipart\.html]
the **Multipart section** for more details, existing Struts `Multipart`
parsers support only `multipart/form-data` content type\. This option is
available since Struts 2\.3\.11\.
+Please read
[RFC1341](https://www.w3.org/Protocols/rfc1341/7\_2\_Multipart.html) the
**Multipart section** for more details, existing
+Struts `Multipart` parsers support only `multipart/form-data` content type.
This option is available since Struts 2.3.11.
-__Disabling file upload support__
+### Disabling file upload support
You can alternatively disable the whole file upload mechanism defining a
constant in `struts.xml`:
-
```xml
<constant name="struts.multipart.enabled" value="false"/>
```
-With this constant in place, Struts will ignore a `Content-Type` header and
will treat each request as an ordinary http request\. This option is available
since Struts 2\.3\.11\.
-
-
+With this constant in place, Struts will ignore a `Content-Type` header and
will treat each request as an ordinary http request.
+This option is available since Struts 2.3.11.
