不透明 URI 中是否允许查询参数？

Question

Java 的 URI class 定义不透明 URI 如下（强调我的）。

A URI is opaque if, and only if, it is absolute and its scheme-specific part does not begin with a slash character ('/'). An opaque URI has a scheme, a scheme-specific part, and possibly a fragment; all other components are undefined.

与文档一致，查询参数的不透明 URI returns null。

URI uri = URI.create("Whosebug:foo?key=value#frag");
uri.isOpaque() == true
uri.getScheme() == Whosebug
uri.getSchemeSpecificPart() == foo?key=value
uri.getQuery() == null
uri.getFragment() == frag

此行为是否特定于 Java 的 URI 实现，或者 URI 规范是否不允许不透明 URI 中的查询参数？

Answer 1

Java的URIclass是documented as conforming to RFC 2396 and RFC 2732:

Aside from some minor deviations noted below, an instance of this class represents a URI reference as defined by RFC 2396: Uniform Resource Identifiers (URI): Generic Syntax, amended by RFC 2732: Format for Literal IPv6 Addresses in URLs.

第 3 节 URI 句法组件 没有明确 disallow opaque 中的查询组件URI，而只是 没有为它们定义 语法。根据定义，不透明的 URI 需要特定于方案的知识才能知道 if 是否存在类似于查询组件的东西以及 how 来解析它。拥有一个是完全合法的，但如果没有这种特殊知识，就不能在一般意义上（根据此 RFC）支持它。相关的 RFC 文本是：

The URI syntax is dependent upon the scheme. In general, absolute URI are written as follows:
<scheme>:<scheme-specific-part>
An absolute URI contains the name of the scheme being used (<scheme>) followed by a colon (":") and then a string (the <scheme-specific-part>) whose interpretation depends on the scheme.

只有 通用语法 提供了 RFC 定义的查询组件，并且该语法要求在第一个冒号 (:) 方案后.

The URI syntax does not require that the scheme-specific-part have any general structure or set of semantics which is common among all URI. However, a subset of URI do share a common syntax for representing hierarchical relationships within the namespace. This "generic URI" syntax consists of a sequence of four main components:
<scheme>://<authority><path>?<query>
each of which, except <scheme>, may be absent from a particular URI. For example, some URI schemes do not allow an <authority> component, and others do not use a <query> component.
absoluteURI   = scheme ":" ( hier_part | opaque_part )

...

hier_part     = ( net_path | abs_path ) [ "?" query ]
net_path      = "//" authority [ abs_path ]>
abs_path      = "/"  path_segments

上述两个 RFC 已 obsoleted by RFC 3986, but for backwards-compatibility reasons Java's existing API and behavior is unlikely to be changed。

URI 实现不同于较新的 RFC，不仅在于它如何定义 URI 的有效组件，而且在行为上。例如，参见：

Is Java's URI.resolve incompatible with RFC 3986 when the relative URI contains an empty path?

快速搜索找到至少一个开源 library 试图提供与 RFC 3986 兼容的实现，但之前的 link 既不是认可也不是推荐。与基于 java.net.URI 的现有 API 的兼容性可能有限。

不透明 URI 中是否允许查询参数？

Are query parameters allowed in opaque URIs?

java

uri

query-parameters