AbstractFileItem (tiny-码云(gitee.com))

java.lang.Object
- org.tinygroup.weblayer.webcontext.parser.impl.AbstractFileItem

All Implemented Interfaces:

Serializable, org.apache.commons.fileupload.FileItem, org.apache.commons.fileupload.FileItemHeadersSupport

Direct Known Subclasses:

DiskFileItem, InMemoryFormFieldItem
```
public abstract class AbstractFileItem
extends Object
implements org.apache.commons.fileupload.FileItem, org.apache.commons.fileupload.FileItemHeadersSupport
```
改进自commons-fileupload-1.2.1的同名类。
解决了如下问题：
1. 原DiskFileItem类（以下简称原类）在解析form field的值时，会利用 content-type头部指定的charset值来决定其字符集编码。例如，下面的 multipart/form-data请求片段指定了myparam field值的字符集编码为 UTF-8：
```
 ----HttpUnit-part0-aSgQ2M
 Content-Disposition: form-data; name="myparam"
 Content-Type: text/plain; charset=UTF-8
 
```
  然而，除了单元测试所用的httpunit/servletunit以外，几乎没有浏览器会在这里指定 content-type以及 charset。因此原类的 getString()总是得不到解码正确的字符串。
2. 原类将内容的长度超过sizeThreshold的字段 —— 无论普通的form fields或是文件字段 —— 均存入文件。这是一种优化。然而在某些情况下，我们希望关闭这种优化 —— 将 sizeThreshold设置成 0 ，以便让所有上传文件无论大小都被存入磁盘。然而仍然希望普通的form fields被保存在内存里。
3. 创建文件时，希望能自动创建目录。
具体改进了如下内容：
- 利用传入的charset参数，而不是content-type来解码form field。但该参数对于文件型字段无效。
- 删除getCharSet()方法，添加getCharset()和 setCharset()方法。
- 修改getString()方法，对form field使用指定的charset来解码。
- 添加keepFormFieldInMemory属性。
- 改进getOutputStream()方法，，当 keepFormFieldInMemory == true时，不将form fields写入文件，即将 threshold设置成Integer.MAX_VALUE。
- 利用File.createTempFile()来生成临时文件，删除原getTempFile() 方法，及相关的getUniqueId()方法、counter field、 tempFile field。
- 改进write()方法，当文件目录不存在时，创建之。
- 改进toString()方法，使之返回文件名，这种形式是为了方便页面引用FileItem对象。
Author:

Michael Zhou

See Also:

Serialized Form

Field Summary

Fields
Modifier and Type	Field and Description
`static String`	`DEFAULT_CHARSET` Default content charset to be used when no explicit charset parameter is provided by the sender.
`protected org.apache.commons.io.output.DeferredFileOutputStream`	`dfos` Output stream for this item.

Constructor Summary

Constructors
Constructor and Description
`AbstractFileItem(String fieldName, String contentType, boolean isFormField, boolean saveInFile, String fileName, int sizeThreshold, boolean keepFormFieldInMemory, File repository, javax.servlet.http.HttpServletRequest request)`
`AbstractFileItem(String fieldName, String contentType, boolean isFormField, boolean saveInFile, String fileName, int sizeThreshold, boolean keepFormFieldInMemory, File repository, javax.servlet.http.HttpServletRequest request, FileUploadReName fileUploadRename)` Constructs a new `DiskFileItem` instance.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`void`	`delete()` Deletes the underlying storage for a file item, including deleting any associated temporary disk file.
`byte[]`	`get()` Returns the contents of the file as an array of bytes.
`String`	`getCharset()` 取得当前field的字符集编码。
`String`	`getContentType()` Returns the content type passed by the agent or `null` if not defined.
`String`	`getFieldName()` Returns the name of the field in the multipart form corresponding to this file item.
`org.apache.commons.fileupload.FileItemHeaders`	`getHeaders()` Returns the file item headers.
`InputStream`	`getInputStream()` Returns an `InputStream` that can be used to retrieve the contents of the file.
`String`	`getName()` Returns the original filename in the client's filesystem.
`OutputStream`	`getOutputStream()` Returns an `OutputStream` that can be used for storing the contents of the file.
`File`	`getRepository()`
`long`	`getSize()` Returns the size of the file.
`File`	`getStoreLocation()` Returns the `File` object for the `FileItem`'s data's temporary location on the disk.
`String`	`getString()` 取得字段或文件的内容。
`String`	`getString(String charset)` Returns the contents of the file as a String, using the specified encoding.
`boolean`	`isFormField()` Determines whether or not a `FileItem` instance represents a simple form field.
`boolean`	`isInMemory()` Provides a hint as to whether or not the file contents will be read from memory.
`void`	`setCharset(String charset)` 设置当前field的字符集编码。
`void`	`setFieldName(String fieldName)` Sets the field name used to reference this file item.
`void`	`setFormField(boolean state)` Specifies whether or not a `FileItem` instance represents a simple form field.
`void`	`setHeaders(org.apache.commons.fileupload.FileItemHeaders pHeaders)` Sets the file item headers.
`String`	`toString()` Returns a string representation of this object.
`void`	`write(File file)` A convenience method to write an uploaded item to disk.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

- Field Detail
  - DEFAULT_CHARSET
```
public static final String DEFAULT_CHARSET
```
    Default content charset to be used when no explicit charset parameter is provided by the sender. Media subtypes of the "text" type are defined to have a default charset value of "ISO-8859-1" when received via HTTP.
    
    See Also:
    
    Constant Field Values
  - dfos
```
protected transient org.apache.commons.io.output.DeferredFileOutputStream dfos
```
    Output stream for this item.
- Constructor Detail
  - AbstractFileItem
```
public AbstractFileItem(String fieldName,
                        String contentType,
                        boolean isFormField,
                        boolean saveInFile,
                        String fileName,
                        int sizeThreshold,
                        boolean keepFormFieldInMemory,
                        File repository,
                        javax.servlet.http.HttpServletRequest request,
                        FileUploadReName fileUploadRename)
```
    Constructs a new DiskFileItem instance.
    
    Parameters:
    
    fieldName - The name of the form field.
    
    contentType - The content type passed by the browser or null if not specified.
    
    isFormField - Whether or not this item is a plain form field, as opposed to a file upload.
    
    fileName - The original filename in the user's filesystem, or null if not specified.
    
    sizeThreshold - The threshold, in bytes, below which items will be retained in memory and above which they will be stored as a file.
    
    repository - The data repository, which is the directory in which files will be created, should the item size exceed the threshold.
  - AbstractFileItem
```
public AbstractFileItem(String fieldName,
                        String contentType,
                        boolean isFormField,
                        boolean saveInFile,
                        String fileName,
                        int sizeThreshold,
                        boolean keepFormFieldInMemory,
                        File repository,
                        javax.servlet.http.HttpServletRequest request)
```
- Method Detail
  - getRepository
```
public File getRepository()
```
  - getInputStream
```
public InputStream getInputStream()
                           throws IOException
```
    Returns an InputStream that can be used to retrieve the contents of the file.
    
    Specified by:
    
    getInputStream in interface org.apache.commons.fileupload.FileItem
    
    Returns:
    
    An InputStream that can be used to retrieve the contents of the file.
    
    Throws:
    
    IOException - if an error occurs.
  - getContentType
```
public String getContentType()
```
    Returns the content type passed by the agent or null if not defined.
    
    Specified by:
    
    getContentType in interface org.apache.commons.fileupload.FileItem
    
    Returns:
    
    The content type passed by the agent or null if not defined.
  - getCharset
```
public String getCharset()
```
    取得当前field的字符集编码。
  - setCharset
```
public void setCharset(String charset)
```
    设置当前field的字符集编码。
  - getName
```
public String getName()
```
    Returns the original filename in the client's filesystem.
    
    Specified by:
    
    getName in interface org.apache.commons.fileupload.FileItem
    
    Returns:
    
    The original filename in the client's filesystem.
  - isInMemory
```
public boolean isInMemory()
```
    Provides a hint as to whether or not the file contents will be read from memory.
    
    Specified by:
    
    isInMemory in interface org.apache.commons.fileupload.FileItem
    
    Returns:
    
    true if the file contents will be read from memory; false otherwise.
  - getSize
```
public long getSize()
```
    Returns the size of the file.
    
    Specified by:
    
    getSize in interface org.apache.commons.fileupload.FileItem
    
    Returns:
    
    The size of the file, in bytes.
  - get
```
public byte[] get()
```
    Returns the contents of the file as an array of bytes. If the contents of the file were not yet cached in memory, they will be loaded from the disk storage and cached.
    
    Specified by:
    
    get in interface org.apache.commons.fileupload.FileItem
    
    Returns:
    
    The contents of the file as an array of bytes.
  - getString
```
public String getString(String charset)
                 throws UnsupportedEncodingException
```
    Returns the contents of the file as a String, using the specified encoding. This method uses get() to retrieve the contents of the file.
    
    Specified by:
    
    getString in interface org.apache.commons.fileupload.FileItem
    
    Parameters:
    
    charset - The charset to use.
    
    Returns:
    
    The contents of the file, as a string.
    
    Throws:
    
    UnsupportedEncodingException - if the requested character encoding is not available.
  - getString
```
public String getString()
```
    取得字段或文件的内容。
    对于form field，将使用传入的charset所指定的字符集编码。
    
    对于文件，使用固定的ISO-8859-1字符集编码。如果想以其它编码来读取文件文本，可使用getString(charset) 方法。
    
    Specified by:
    
    getString in interface org.apache.commons.fileupload.FileItem
    
    Returns:
    
    字段值或文件文本
  - write
```
public void write(File file)
           throws Exception
```
    A convenience method to write an uploaded item to disk. The client code is not concerned with whether or not the item is stored in memory, or on disk in a temporary location. They just want to write the uploaded item to a file.
    This implementation first attempts to rename the uploaded item to the specified destination file, if the item was originally written to disk. Otherwise, the data will be copied to the specified file.
    This method is only guaranteed to work once, the first time it is invoked for a particular item. This is because, in the event that the method renames a temporary file, that file will no longer be available to copy or rename again at a later time.
    
    Specified by:
    
    write in interface org.apache.commons.fileupload.FileItem
    
    Parameters:
    
    file - The File into which the uploaded item should be stored.
    
    Throws:
    
    Exception - if an error occurs.
  - delete
```
public void delete()
```
    Deletes the underlying storage for a file item, including deleting any associated temporary disk file. Although this storage will be deleted automatically when the FileItem instance is garbage collected, this method can be used to ensure that this is done at an earlier time, thus preserving system resources.
    
    Specified by:
    
    delete in interface org.apache.commons.fileupload.FileItem
  - getFieldName
```
public String getFieldName()
```
    Returns the name of the field in the multipart form corresponding to this file item.
    
    Specified by:
    
    getFieldName in interface org.apache.commons.fileupload.FileItem
    
    Returns:
    
    The name of the form field.
    
    See Also:
    
    setFieldName(java.lang.String)
  - setFieldName
```
public void setFieldName(String fieldName)
```
    Sets the field name used to reference this file item.
    
    Specified by:
    
    setFieldName in interface org.apache.commons.fileupload.FileItem
    
    Parameters:
    
    fieldName - The name of the form field.
    
    See Also:
    
    getFieldName()
  - isFormField
```
public boolean isFormField()
```
    Determines whether or not a FileItem instance represents a simple form field.
    
    Specified by:
    
    isFormField in interface org.apache.commons.fileupload.FileItem
    
    Returns:
    
    true if the instance represents a simple form field; false if it represents an uploaded file.
    
    See Also:
    
    setFormField(boolean)
  - setFormField
```
public void setFormField(boolean state)
```
    Specifies whether or not a FileItem instance represents a simple form field.
    
    Specified by:
    
    setFormField in interface org.apache.commons.fileupload.FileItem
    
    Parameters:
    
    state - true if the instance represents a simple form field; false if it represents an uploaded file.
    
    See Also:
    
    isFormField()
  - getOutputStream
```
public OutputStream getOutputStream()
                             throws IOException
```
    Returns an OutputStream that can be used for storing the contents of the file.
    
    Specified by:
    
    getOutputStream in interface org.apache.commons.fileupload.FileItem
    
    Returns:
    
    An OutputStream that can be used for storing the contensts of the file.
    
    Throws:
    
    IOException - if an error occurs.
  - getStoreLocation
```
public File getStoreLocation()
```
    Returns the File object for the FileItem's data's temporary location on the disk. Note that for FileItems that have their data stored in memory, this method will return null. When handling large files, you can use File.renameTo(java.io.File) to move the file to new location without copying the data, if the source and destination locations reside within the same logical volume.
    
    Returns:
    
    The data file, or null if the data is stored in memory.
  - toString
```
public String toString()
```
    Returns a string representation of this object.
    
    Overrides:
    
    toString in class Object
    
    Returns:
    
    a string representation of this object.
  - getHeaders
```
public org.apache.commons.fileupload.FileItemHeaders getHeaders()
```
    Returns the file item headers.
    
    Specified by:
    
    getHeaders in interface org.apache.commons.fileupload.FileItemHeadersSupport
    
    Returns:
    
    The file items headers.
  - setHeaders
```
public void setHeaders(org.apache.commons.fileupload.FileItemHeaders pHeaders)
```
    Sets the file item headers.
    
    Specified by:
    
    setHeaders in interface org.apache.commons.fileupload.FileItemHeadersSupport
    
    Parameters:
    
    pHeaders - The file items headers.

Class AbstractFileItem

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

DEFAULT_CHARSET

dfos

Constructor Detail

AbstractFileItem

AbstractFileItem

Method Detail

getRepository

getInputStream

getContentType

getCharset

setCharset

getName

isInMemory

getSize

get

getString

getString

write

delete

getFieldName

setFieldName

isFormField

setFormField

getOutputStream

getStoreLocation

toString

getHeaders

setHeaders