application/xml and text/xml的區別
經常看到有關xml時提到"application/xml" 和 "text/xml"兩種類型， 二者功能一模一樣，唯一的區別就是編碼格式，text/xml忽略xml頭所指定編碼格式而默認采用us-ascii編碼，而application/xml會根據xml頭指定的編碼格式來編碼：
XML has two MIME types,application/xml and text/xml . These are often used interchangeably, but there is a subtle difference which is why application/xml is generally recommended over the latter.
Let me explain why: according to the standard, text/* -MIME types have a us-ascii character set unless otherwise specified in the HTTP headers. This effectively means that any encoding defined in the XML prolog (e.g. <?xml version=”1.0” encoding=”UTF-8”?>) is ignored. This is of course not the expected and desired behaviour.
To further complicate matters, most/all browser implementations actually implement nonstandard behaviour for text/xml because they process the encoding as if it were application/xml .
So, text/* has encoding issues, and is not implemented by browsers in a standards-compliant manner, which is why using application/* is recommended.
text/xml 和 application/xml的字符集編碼問題
關鍵字: text/xml application/xml
對於Webservice的應用來說，我們通常都是用UTF-8進行網絡傳輸，但也有通過GBK和GB2312傳輸的情況，但是在我們Webservice的代碼實現中，其實是不用關心具體的傳輸編碼的，因為根據RFC2376的定義，Webservice的引擎（axis，cxf，jaxws..）會根據文件傳輸的ContentType及XML 聲明部分定義的編碼自動將網絡傳輸過來的內容（字符串）轉換成unicode（jvm運行時的字符串都是以unicode形式存在的）。以下是RFC2376的描述：
例子1：
webservice傳輸的文件
- Content-type: application/xml; charset="utf-16"
- {BOM}<?xml version="1.0"?>
- Content-type: application/xml; charset="utf-16"
- {BOM}<?xml version="1.0"?>
XML and MIME processors會按照utf-16編碼處理該文件
例子2：
webservice傳輸的文件
- Content-type: application/xml
- <?xml version='1.0'?>
- Content-type: application/xml
- <?xml version='1.0'?>
XML processors會按照utf-8編碼處理該文件
例子3：
webservice傳輸的文件
- Content-type: application/xml
- <?xml version='1.0' encoding="ISO-10646-UCS-4"?>
- Content-type: application/xml
- <?xml version='1.0' encoding="ISO-10646-UCS-4"?>
XML processors會按照UCS-4編碼處理該文件
例子4：
webservice傳輸的文件
- Content-type: text/xml
- {BOM}<?xml version="1.0" encoding="utf-16"?>
- Content-type: text/xml
- {BOM}<?xml version="1.0" encoding="utf-16"?>
XML processors會按照us-ascii，而不是utf-16編碼處理該文件
參考文檔：