Part (Java EE 5)

Java EE API

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javax.mail Interface Part

All Known Subinterfaces:
MimePart
All Known Implementing Classes:
BodyPart, Message, MimeBodyPart, MimeMessage, PreencodedMimeBodyPart
public interface Part

Implemented by: BodyPart, Message, MimePart

Part 接口是 Message 和 BodyPart 的公共基本接口。

Part 由一个属性集和一个 "Content" 组成。

属性：

JavaMail API 定义了一组标准 Part 属性，这些属性通用于大多数现有 Mail 系统。这些属性有自己的设置方法和获取方法。Mail 系统可能还支持其他 Part 属性，这些属性是以名称-值对的形式表示的，其中名称和值都是 String。

内容：

"content" 的数据类型由 getContentType() 方法返回。MIME 类型系统用于指定数据类型。

Part 的 "content" 有多种格式：

  • 作为 DataHandler - 使用 getDataHandler() 方法。Part 的 "content" 还可通过 javax.activation.DataHandler 对象获取。DataHandler 对象允许客户端发现可以对内容进行的操作，并实例化相应的组件来执行这些操作。
  • 作为输入流 - 使用 getInputStream() 方法。所有特定于邮件的编码都是在返回此流之前解码的。
  • 作为 Java 对象 - 使用 getContent() 方法。此方法以 Java 对象的形式返回 "content"。返回的对象无疑取决于内容本身。需要特别指出的是，"multipart" Part 的内容总是 Multipart 或其子类。也就是说，对 "multipart" 类型的 Part 调用 getContent() 将总是返回 Multipart（或子类）对象。
Part 提供 writeTo() 方法，该方法以适用于传输的、对邮件安全的形式传出字节流。此字节流通常是 Part 属性及其内容的字节流的聚合。

Message 和 BodyPart 实现 Part 接口。注意，在 MIME 用法中，Part 将模拟 Entity（RFC 2045 的第 2.4 节）。

英文文档：

The Part interface is the common base interface for Messages and BodyParts.

Part consists of a set of attributes and a "Content".

Attributes:

The JavaMail API defines a set of standard Part attributes that are considered to be common to most existing Mail systems. These attributes have their own settor and gettor methods. Mail systems may support other Part attributes as well, these are represented as name-value pairs where both the name and value are Strings.

Content:

The data type of the "content" is returned by the getContentType() method. The MIME typing system is used to name data types.

The "content" of a Part is available in various formats:

  • As a DataHandler - using the getDataHandler() method. The "content" of a Part is also available through a javax.activation.DataHandler object. The DataHandler object allows clients to discover the operations available on the content, and to instantiate the appropriate component to perform those operations.
  • As an input stream - using the getInputStream() method. Any mail-specific encodings are decoded before this stream is returned.
  • As a Java object - using the getContent() method. This method returns the "content" as a Java object. The returned object is of course dependent on the content itself. In particular, a "multipart" Part's content is always a Multipart or subclass thereof. That is, getContent() on a "multipart" type Part will always return a Multipart (or subclass) object.
Part provides the writeTo() method that streams out its bytestream in mail-safe form suitable for transmission. This bytestream is typically an aggregation of the Part attributes and its content's bytestream.

Message and BodyPart implement the Part interface. Note that in MIME parlance, Part models an Entity (RFC 2045, Section 2.4).

Author:
John Mani

Field Summary
static String ATTACHMENT
          This part should be presented as an attachment.
static String INLINE
          This part should be presented inline.
 
Method Summary
 void addHeader(String header_name, String header_value)
          Add this value to the existing values for this header_name.
 Enumeration getAllHeaders()
          Return all the headers from this part as an Enumeration of Header objects.
 Object getContent()
          Return the content as a Java object.
 String getContentType()
          Returns the Content-Type of the content of this part.
 DataHandler getDataHandler()
          Return a DataHandler for the content within this part.
 String getDescription()
          Return a description String for this part.
 String getDisposition()
          Return the disposition of this part.
 String getFileName()
          Get the filename associated with this part, if possible.
 String[] getHeader(String header_name)
          Get all the headers for this header name.
 InputStream getInputStream()
          Return an input stream for this part's "content".
 int getLineCount()
          Return the number of lines in the content of this part.
 Enumeration getMatchingHeaders(String[] header_names)
          Return matching headers from this part as an Enumeration of Header objects.
 Enumeration getNonMatchingHeaders(String[] header_names)
          Return non-matching headers from this envelope as an Enumeration of Header objects.
 int getSize()
          Return the size of the content of this part in bytes.
 boolean isMimeType(String mimeType)
          Is this Part of the specified MIME type?
 void removeHeader(String header_name)
          Remove all headers with this name.
 void setContent(Multipart mp)
          This method sets the given Multipart object as this message's content.
 void setContent(Object obj, String type)
          A convenience method for setting this part's content.
 void setDataHandler(DataHandler dh)
          This method provides the mechanism to set this part's content.
 void setDescription(String description)
          Set a description String for this part.
 void setDisposition(String disposition)
          Set the disposition of this part.
 void setFileName(String filename)
          Set the filename associated with this part, if possible.
 void setHeader(String header_name, String header_value)
          Set the value for this header_name.
 void setText(String text)
          A convenience method that sets the given String as this part's content with a MIME type of "text/plain".
 void writeTo(OutputStream os)
          Output a bytestream for this Part.
 

Field Detail

英文文档：

ATTACHMENT 

static final String ATTACHMENT
This part should be presented as an attachment.

See Also:
getDisposition(), setDisposition(java.lang.String), Constant Field Values

英文文档：

INLINE 

static final String INLINE
This part should be presented inline.

See Also:
getDisposition(), setDisposition(java.lang.String), Constant Field Values

Method Detail

public int getSize() throws MessagingException
返回此部分的内容大小（以字节为单位）。如果无法确定大小，则返回 -1。

注意，该大小可能不是内容大小的准确度量，可能没有考虑内容的传输编码。该大小适合显示在用户界面中，为用户提供此部分的大小的粗略参考。

return 内容大小（以字节为单位）
ThrowsMessagingException:

英文文档：

getSize

int getSize()
            throws MessagingException
Return the size of the content of this part in bytes. Return -1 if the size cannot be determined.

Note that the size may not be an exact measure of the content size and may or may not account for any transfer encoding of the content. The size is appropriate for display in a user interface to give the user a rough idea of the size of this part.

Returns:
size of content in bytes
Throws:
MessagingException

public int getLineCount() throws MessagingException
返回此部分的内容的行数。如果无法确定该数值，则返回 -1。 注意，此数值可能不是内容长度的准确度量，可能没有考虑内容的传输编码。
return 内容的行数。
ThrowsMessagingException:
英文文档：

getLineCount

int getLineCount()
                 throws MessagingException
Return the number of lines in the content of this part. Return -1 if the number cannot be determined. Note that this number may not be an exact measure of the content length and may or may not account for any transfer encoding of the content.

Returns:
number of lines in the content.
Throws:
MessagingException

public String getContentType() throws MessagingException
返回此部分的内容的 Content-Type。如果 Content-Type 无法确定，则返回 null。

MIME 类型系统用于指定 Content-type。

return 此部分的 ContentType
ThrowsMessagingException:
See also javax.activation.DataHandler

英文文档：

getContentType

String getContentType()
                      throws MessagingException
Returns the Content-Type of the content of this part. Returns null if the Content-Type could not be determined.

The MIME typing system is used to name Content-types.

Returns:
The ContentType of this part
Throws:
MessagingException
See Also:
DataHandler

public boolean isMimeType(String mimeType) throws MessagingException
此 Part 是指定的 MIME 类型吗？此方法仅比较 primaryType 和 subType。忽略内容类型参数。

例如，当比较内容类型的 "text/plain" 部分与 "text/plain; charset=foobar" 时，此方法将返回 true。

如果 mimeType 的 subType 是特殊字符 '*'，则比较过程中将忽略 subtype。

英文文档：

isMimeType

boolean isMimeType(String mimeType)
                   throws MessagingException
Is this Part of the specified MIME type? This method compares only the primaryType and subType. The parameters of the content types are ignored.

For example, this method will return true when comparing a Part of content type "text/plain" with "text/plain; charset=foobar".

If the subType of mimeType is the special character '*', then the subtype is ignored during the comparison.

Throws:
MessagingException

public String getDisposition() throws MessagingException
返回此部分的 disposition。disposition 描述各部分应该如何展示给用户。（请参见 RFC 2183。）返回值应该不考虑大小写。例如： 

String disp = part.getDisposition();
if (disp == null || disp.equalsIgnoreCase(Part.ATTACHMENT))
	// treat as attachment if not first part
return 此部分的 disposition；如果未知，则返回 null
ThrowsMessagingException:
See also ATTACHMENT, INLINE, getFileName
英文文档：

getDisposition

String getDisposition()
                      throws MessagingException
Return the disposition of this part. The disposition describes how the part should be presented to the user. (See RFC 2183.) The return value should be considered without regard to case. For example: 

 String disp = part.getDisposition();
 if (disp == null || disp.equalsIgnoreCase(Part.ATTACHMENT))
        // treat as attachment if not first part

Returns:
disposition of this part, or null if unknown
Throws:
MessagingException
See Also:
ATTACHMENT, INLINE, getFileName()

public void setDisposition(String disposition) throws MessagingException
设置此部分的 disposition。
disposition 此部分的 disposition
ThrowsMessagingException:
ThrowsIllegalWriteException: 如果底层实现不支持修改此头
ThrowsIllegalStateException: 如果此 Part 可从 READ_ONLY 文件夹获取
See also ATTACHMENT, INLINE, setFileName
英文文档：

setDisposition

void setDisposition(String disposition)
                    throws MessagingException
Set the disposition of this part.

Parameters:
disposition - disposition of this part
Throws:
MessagingException
IllegalWriteException - if the underlying implementation does not support modification of this header
IllegalStateException - if this Part is obtained from a READ_ONLY folder
See Also:
ATTACHMENT, INLINE, setFileName(java.lang.String)

public String getDescription() throws MessagingException
返回此部分的描述 String。这通常包括一些与此部分关联的描述性信息。如果不存在，则返回 null。
return 此部分的描述
ThrowsMessagingException:
英文文档：

getDescription

String getDescription()
                      throws MessagingException
Return a description String for this part. This typically associates some descriptive information with this part. Returns null if none is available.

Returns:
description of this part
Throws:
MessagingException

public void setDescription(String description) throws MessagingException
设置此部分的描述 String。这通常包括一些与此部分关联的描述性信息。
description 此部分的描述
ThrowsMessagingException:
ThrowsIllegalWriteException: 如果底层实现不支持修改此头
ThrowsIllegalStateException: 如果此 Part 可从 READ_ONLY 文件夹获取
英文文档：

setDescription

void setDescription(String description)
                    throws MessagingException
Set a description String for this part. This typically associates some descriptive information with this part.

Parameters:
description - description of this part
Throws:
MessagingException
IllegalWriteException - if the underlying implementation does not support modification of this header
IllegalStateException - if this Part is obtained from a READ_ONLY folder

public String getFileName() throws MessagingException
如果可能，获取与此部分关联的文件名称。在此部分表示从文件加载的“附件”时非常有用。该文件名通常是一个简单名称，不包含目录组件。
return 与此部分关联的文件名称
英文文档：

getFileName

String getFileName()
                   throws MessagingException
Get the filename associated with this part, if possible. Useful if this part represents an "attachment" that was loaded from a file. The filename will usually be a simple name, not including directory components.

Returns:
Filename to associate with this part
Throws:
MessagingException

public void setFileName(String filename) throws MessagingException
如果可能，设置与此部分关联的文件名称。在此部分表示从文件加载的“附件”时非常有用。该文件名通常是一个简单名称，不包含目录组件。
filename 与此部分关联的文件名称
ThrowsIllegalWriteException: 如果底层实现不支持修改此头
ThrowsIllegalStateException: 如果此 Part 可从 READ_ONLY 文件夹获取
英文文档：

setFileName

void setFileName(String filename)
                 throws MessagingException
Set the filename associated with this part, if possible. Useful if this part represents an "attachment" that was loaded from a file. The filename will usually be a simple name, not including directory components.

Parameters:
filename - Filename to associate with this part
Throws:
IllegalWriteException - if the underlying implementation does not support modification of this header
IllegalStateException - if this Part is obtained from a READ_ONLY folder
MessagingException

public java.io.InputStream getInputStream() throws java.io.IOException, MessagingException
返回用于此部分的 "content" 的输入流。所有特定于邮件的传输编码都将在提供输入流之前解码。

这通常是一个便捷方法，该方法只调用 DataHandler 的 getInputStream() 方法。

return InputStream
Throwsjava.io.IOException: 此异常通常由 DataHandler 抛出。有关更多信息，请参考 javax.activation.DataHandler 的文档。
ThrowsMessagingException:
See also getDataHandler, getInputStream

英文文档：

getInputStream

InputStream getInputStream()
                           throws IOException,
                                  MessagingException
Return an input stream for this part's "content". Any mail-specific transfer encodings will be decoded before the input stream is provided.

This is typically a convenience method that just invokes the DataHandler's getInputStream() method.

Returns:
an InputStream
Throws:
IOException - this is typically thrown by the DataHandler. Refer to the documentation for javax.activation.DataHandler for more details.
MessagingException
See Also:
getDataHandler(), DataHandler.getInputStream()

public DataHandler getDataHandler() throws MessagingException
返回用于此部分的内容的 DataHandler。DataHandler 允许客户端操作和获取内容。
return 内容的 DataHandler
ThrowsMessagingException:
英文文档：

getDataHandler

DataHandler getDataHandler()
                           throws MessagingException
Return a DataHandler for the content within this part. The DataHandler allows clients to operate on as well as retrieve the content.

Returns:
DataHandler for the content
Throws:
MessagingException

public Object getContent() throws java.io.IOException, MessagingException
以 Java 对象的形式返回内容。所返回对象的类型当然取决于内容本身。例如，"text/plain" 内容的返回对象通常为 String 对象。"multipart" 内容的返回对象总是 Multipart 子类。对于 DataHandler 系统未知的内容类型，将输入流作为内容返回。

这是一个便捷方法，该方法只调用 DataHandler 的 getContent() 方法。

return 对象
ThrowsMessagingException:
Throwsjava.io.IOException: 此异常通常由 DataHandler 抛出。有关更多信息，请参考 javax.activation.DataHandler 的文档。
See also getContent

英文文档：

getContent

Object getContent()
                  throws IOException,
                         MessagingException
Return the content as a Java object. The type of the returned object is of course dependent on the content itself. For example, the object returned for "text/plain" content is usually a String object. The object returned for a "multipart" content is always a Multipart subclass. For content-types that are unknown to the DataHandler system, an input stream is returned as the content

This is a convenience method that just invokes the DataHandler's getContent() method

Returns:
Object
Throws:
MessagingException
IOException - this is typically thrown by the DataHandler. Refer to the documentation for javax.activation.DataHandler for more details.
See Also:
DataHandler.getContent()

public void setDataHandler(DataHandler dh) throws MessagingException
此方法提供设置此部分的内容的机制。DataHandler 包装实际的内容。
dh 用于内容的 DataHandler。
ThrowsMessagingException:
ThrowsIllegalWriteException: 如果底层实现不支持修改现有值
ThrowsIllegalStateException: 如果此 Part 可从 READ_ONLY 文件夹获取
英文文档：

setDataHandler

void setDataHandler(DataHandler dh)
                    throws MessagingException
This method provides the mechanism to set this part's content. The DataHandler wraps around the actual content.

Parameters:
dh - The DataHandler for the content.
Throws:
MessagingException
IllegalWriteException - if the underlying implementation does not support modification of existing values
IllegalStateException - if this Part is obtained from a READ_ONLY folder

public void setContent(Object obj, String type) throws MessagingException
设置此部分的内容的便捷方法。该部分将内容包装在 DataHandler 内部。

注意，为了正常运行，指定类型的 DataContentHandler 类应该可用于 JavaMail 实现，即要执行 setContent(foobar, "application/x-foobar")，必须安装 "application/x-foobar" 的 DataContentHandler。有关更多信息，请参考 Java Activation Framework。

obj Java 对象。
type 此对象的 MIME 类型。
ThrowsIllegalWriteException: 如果底层实现不支持修改现有值
ThrowsIllegalStateException: 如果此 Part 可从 READ_ONLY 文件夹获取

英文文档：

setContent

void setContent(Object obj,
                String type)
                throws MessagingException
A convenience method for setting this part's content. The part internally wraps the content in a DataHandler.

Note that a DataContentHandler class for the specified type should be available to the JavaMail implementation for this to work right. i.e., to do setContent(foobar, "application/x-foobar"), a DataContentHandler for "application/x-foobar" should be installed. Refer to the Java Activation Framework for more information.

Parameters:
obj - A java object.
type - MIME type of this object.
Throws:
IllegalWriteException - if the underlying implementation does not support modification of existing values
IllegalStateException - if this Part is obtained from a READ_ONLY folder
MessagingException

public void setText(String text) throws MessagingException
使用 MIME 类型 "text/plain" 将给定的 String 设置为此部分内容的便捷方法。
text 作为 Message 内容的文本。
ThrowsIllegalWriteException: 如果底层实现不支持修改现有值
ThrowsIllegalStateException: 如果此 Part 可从 READ_ONLY 文件夹获取
英文文档：

setText

void setText(String text)
             throws MessagingException
A convenience method that sets the given String as this part's content with a MIME type of "text/plain".

Parameters:
text - The text that is the Message's content.
Throws:
IllegalWriteException - if the underlying implementation does not support modification of existing values
IllegalStateException - if this Part is obtained from a READ_ONLY folder
MessagingException

public void setContent(Multipart mp) throws MessagingException
此方法将给定的 Multipart 对象设置为此消息的内容。
mp 为 Message 的内容的 multipart 对象。
ThrowsIllegalWriteException: 如果底层实现 不支持修改现有值
ThrowsIllegalStateException: 如果此 Part 可从 READ_ONLY 文件夹获取
英文文档：

setContent

void setContent(Multipart mp)
                throws MessagingException
This method sets the given Multipart object as this message's content.

Parameters:
mp - The multipart object that is the Message's content
Throws:
IllegalWriteException - if the underlying implementation does not support modification of existing values
IllegalStateException - if this Part is obtained from a READ_ONLY folder
MessagingException

public void writeTo(java.io.OutputStream os) throws java.io.IOException, MessagingException
输出此 Part 的字节流。此字节流通常是 Part 属性及其 'content' 中已恰当编码的字节流的聚合。

实现 Part 接口的类决定了要使用的相应编码算法。

字节流通常用于发送。

Throwsjava.io.IOException: 如果写入流时发生错误，或者 javax.activation 层发生错误。
ThrowsMessagingException: 如果获取要写入的数据时发生错误
See also writeTo

英文文档：

writeTo

void writeTo(OutputStream os)
             throws IOException,
                    MessagingException
Output a bytestream for this Part. This bytestream is typically an aggregration of the Part attributes and an appropriately encoded bytestream from its 'content'.

Classes that implement the Part interface decide on the appropriate encoding algorithm to be used.

The bytestream is typically used for sending.

Throws:
IOException - if an error occurs writing to the stream or if an error is generated by the javax.activation layer.
MessagingException - if an error occurs fetching the data to be written
See Also:
DataHandler.writeTo(java.io.OutputStream)

public String[] getHeader(String header_name) throws MessagingException
获取具有此头名称的所有头。如果不存在具有此名称的头，则返回 null。
header_name 此头的名称
return 具有此名称的所有头的值字段
ThrowsMessagingException:
英文文档：

getHeader

String[] getHeader(String header_name)
                   throws MessagingException
Get all the headers for this header name. Returns null if no headers for this header name are available.

Parameters:
header_name - the name of this header
Returns:
the value fields for all headers with this name
Throws:
MessagingException

public void setHeader(String header_name, String header_value) throws MessagingException
设置此 header_name 的值。使用此新值替换所有现有的头值。
header_name 此头的名称
header_value 此头的值
ThrowsMessagingException:
ThrowsIllegalWriteException: 如果底层实现不支持修改现有值
ThrowsIllegalStateException: 如果此 Part 可从 READ_ONLY 文件夹获取
英文文档：

setHeader

void setHeader(String header_name,
               String header_value)
               throws MessagingException
Set the value for this header_name. Replaces all existing header values with this new value.

Parameters:
header_name - the name of this header
header_value - the value for this header
Throws:
MessagingException
IllegalWriteException - if the underlying implementation does not support modification of existing values
IllegalStateException - if this Part is obtained from a READ_ONLY folder

public void addHeader(String header_name, String header_value) throws MessagingException
将此值添加到此 header_name 的现有值中。
header_name 此头的名称
header_value 此头的值
ThrowsMessagingException:
ThrowsIllegalWriteException: 如果底层实现不支持修改现有值
ThrowsIllegalStateException: 如果此 Part 可从 READ_ONLY 文件夹获取
英文文档：

addHeader

void addHeader(String header_name,
               String header_value)
               throws MessagingException
Add this value to the existing values for this header_name.

Parameters:
header_name - the name of this header
header_value - the value for this header
Throws:
MessagingException
IllegalWriteException - if the underlying implementation does not support modification of existing values
IllegalStateException - if this Part is obtained from a READ_ONLY folder

public void removeHeader(String header_name) throws MessagingException
移除具有此名称的所有头。
header_name 此头的名称
ThrowsMessagingException:
ThrowsIllegalWriteException: 如果底层实现不支持修改现有值
ThrowsIllegalStateException: 如果此 Part 可从 READ_ONLY 文件夹获取
英文文档：

removeHeader

void removeHeader(String header_name)
                  throws MessagingException
Remove all headers with this name.

Parameters:
header_name - the name of this header
Throws:
MessagingException
IllegalWriteException - if the underlying implementation does not support modification of existing values
IllegalStateException - if this Part is obtained from a READ_ONLY folder

public java.util.Enumeration<E> getAllHeaders() throws MessagingException
以 Header 对象的枚举形式返回此部分的所有头。
return Header 对象的枚举
ThrowsMessagingException:
英文文档：

getAllHeaders

Enumeration getAllHeaders()
                          throws MessagingException
Return all the headers from this part as an Enumeration of Header objects.

Returns:
enumeration of Header objects
Throws:
MessagingException

public java.util.Enumeration<E> getMatchingHeaders(String[] header_names) throws MessagingException
以 Header 对象的枚举形式返回此部分的匹配头。
return Header 对象的枚举
ThrowsMessagingException:
英文文档：

getMatchingHeaders

Enumeration getMatchingHeaders(String[] header_names)
                               throws MessagingException
Return matching headers from this part as an Enumeration of Header objects.

Returns:
enumeration of Header objects
Throws:
MessagingException

public java.util.Enumeration<E> getNonMatchingHeaders(String[] header_names) throws MessagingException
以 Header 对象的枚举形式返回此封装中不匹配的头。
return Header 对象的枚举
ThrowsMessagingException:
英文文档：

getNonMatchingHeaders

Enumeration getNonMatchingHeaders(String[] header_names)
                                  throws MessagingException
Return non-matching headers from this envelope as an Enumeration of Header objects.

Returns:
enumeration of Header objects
Throws:
MessagingException
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一看就知道只有菜鸟才干这么无知的事啦。

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