类 HttpUrl
http or https. Use this
class to compose and decompose Internet addresses. For example, this code will compose and print
a URL for Google search:
HttpUrl url = new HttpUrl.Builder()
.scheme("https")
.host("www.google.com")
.addPathSegment("search")
.addQueryParameter("q", "polar bears")
.build();
System.out.println(url);
which prints:
https://www.google.com/search?q=polar%20bears
As another example, this code prints the human-readable query parameters of a Twitter search:
HttpUrl url = HttpUrl.parse("https://twitter.com/search?q=cute%20%23puppies&f=images");
for (int i = 0, size = url.querySize(); i < size; i++) {
System.out.println(url.queryParameterName(i) + ": " + url.queryParameterValue(i));
}
which prints:
q: cute #puppies
f: images
In addition to composing URLs from their component parts and decomposing URLs into their component parts, this class implements relative URL resolution: what address you'd reach by clicking a relative link on a specified page. For example:
HttpUrl base = HttpUrl.parse("https://www.youtube.com/user/WatchTheDaily/videos");
HttpUrl link = base.resolve("../../watch?v=cbP2N1BQdYc");
System.out.println(link);
which prints:
https://www.youtube.com/watch?v=cbP2N1BQdYc
What's in a URL?
A URL has several components.
Scheme
Sometimes referred to as protocol, A URL's scheme describes what mechanism should be
used to retrieve the resource. Although URLs have many schemes (mailto, file,
ftp), this class only supports http and https. Use java.net.URI for URLs with arbitrary schemes.
Username and Password
Username and password are either present, or the empty string "" if absent. This
class offers no mechanism to differentiate empty from absent. Neither of these components are
popular in practice. Typically HTTP applications use other mechanisms for user identification and
authentication.
Host
The host identifies the webserver that serves the URL's resource. It is either a hostname
like square.com or localhost, an IPv4 address like 192.168.0.1, or an
IPv6 address like ::1.
Usually a webserver is reachable with multiple identifiers: its IP addresses, registered
domain names, and even localhost when connecting from the server itself. Each of a
webserver's names is a distinct URL and they are not interchangeable. For example, even if
http://square.github.io/dagger and http://google.github.io/dagger are served by the same
IP address, the two URLs identify different resources.
Port
The port used to connect to the webserver. By default this is 80 for HTTP and 443 for HTTPS. This class never returns -1 for the port: if no port is explicitly specified in the URL then the scheme's default is used.
Path
The path identifies a specific resource on the host. Paths have a hierarchical structure like "/square/okhttp/issues/1486" and decompose into a list of segments like ["square", "okhttp", "issues", "1486"].
This class offers methods to compose and decompose paths by segment. It composes each path from a list of segments by alternating between "/" and the encoded segment. For example the segments ["a", "b"] build "/a/b" and the segments ["a", "b", ""] build "/a/b/".
If a path's last segment is the empty string then the path ends with "/". This class always builds non-empty paths: if the path is omitted it defaults to "/". The default path's segment list is a single empty string: [""].
Query
The query is optional: it can be null, empty, or non-empty. For many HTTP URLs the query string is subdivided into a collection of name-value parameters. This class offers methods to set the query as the single string, or as individual name-value parameters. With name-value parameters the values are optional and names may be repeated.
Fragment
The fragment is optional: it can be null, empty, or non-empty. Unlike host, port, path, and query the fragment is not sent to the webserver: it's private to the client.
Encoding
Each component must be encoded before it is embedded in the complete URL. As we saw above,
the string cute #puppies is encoded as cute%20%23puppies when used as a query
parameter value.
Percent encoding
Percent encoding replaces a character (like 🍩) with its UTF-8 hex bytes
(like %F0%9F%8D%A9). This approach works for whitespace characters, control characters,
non-ASCII characters, and characters that already have another meaning in a particular context.
Percent encoding is used in every URL component except for the hostname. But the set of
characters that need to be encoded is different for each component. For example, the path
component must escape all of its ? characters, otherwise it could be interpreted as the
start of the URL's query. But within the query and fragment components, the ? character
doesn't delimit anything and doesn't need to be escaped.
HttpUrl url = HttpUrl.parse("http://who-let-the-dogs.out").newBuilder()
.addPathSegment("_Who?_")
.query("_Who?_")
.fragment("_Who?_")
.build();
System.out.println(url);
This prints:
http://who-let-the-dogs.out/_Who%3F_?_Who?_#_Who?_
When parsing URLs that lack percent encoding where it is required, this class will percent encode the offending characters.
IDNA Mapping and Punycode encoding
Hostnames have different requirements and use a different encoding scheme. It consists of IDNA mapping and Punycode encoding.
In order to avoid confusion and discourage phishing attacks, IDNA Mapping transforms names to avoid
confusing characters. This includes basic case folding: transforming shouting SQUARE.COM
into cool and casual square.com. It also handles more exotic characters. For example, the
Unicode trademark sign (™) could be confused for the letters "TM" in http://ho™mail.com.
To mitigate this, the single character (™) maps to the string (tm). There is similar policy for
all of the 1.1 million Unicode code points. Note that some code points such as "🍩" are
not mapped and cannot be used in a hostname.
Punycode converts a Unicode string to an ASCII
string to make international domain names work everywhere. For example, "σ" encodes as "xn--4xa".
The encoded string is not human readable, but can be used with classes like InetAddress
to establish connections.
Why another URL model?
Java includes both java.net.URL and java.net.URI. We offer a new URL
model to address problems that the others don't.
Different URLs should be different
Although they have different content, java.net.URL considers the following two URLs
equal, and the equals() method between them returns true:
- http://square.github.io/
- http://google.github.io/
This is because those two hosts share the same IP address. This is an old, bad design decision
that makes java.net.URL unusable for many things. It shouldn't be used as a Map key or in a Set. Doing so is both inefficient because equality may
require a DNS lookup, and incorrect because unequal URLs may be equal because of how they are
hosted.
Equal URLs should be equal
These two URLs are semantically identical, but java.net.URI disagrees:
- http://host:80/
- http://host
Both the unnecessary port specification (:80) and the absent trailing slash (/)
cause URI to bucket the two URLs separately. This harms URI's usefulness in collections. Any
application that stores information-per-URL will need to either canonicalize manually, or suffer
unnecessary redundancy for such URLs.
Because they don't attempt canonical form, these classes are surprisingly difficult to use securely. Suppose you're building a webservice that checks that incoming paths are prefixed "/static/images/" before serving the corresponding assets from the filesystem.
String attack = "http://example.com/static/images/../../../../../etc/passwd";
System.out.println(new URL(attack).getPath());
System.out.println(new URI(attack).getPath());
System.out.println(HttpUrl.parse(attack).encodedPath());
By canonicalizing the input paths, they are complicit in directory traversal attacks. Code that checks only the path prefix may suffer!
/static/images/../../../../../etc/passwd
/static/images/../../../../../etc/passwd
/etc/passwd
If it works on the web, it should work in your application
The java.net.URI class is strict around what URLs it accepts. It rejects URLs like
"http://example.com/abc|def" because the '|' character is unsupported. This class is more
forgiving: it will automatically percent-encode the '|', yielding "http://example.com/abc%7Cdef".
This kind behavior is consistent with web browsers. HttpUrl prefers consistency with
major web browsers over consistency with obsolete specifications.
Paths and Queries should decompose
Neither of the built-in URL models offer direct access to path segments or query parameters.
Manually using StringBuilder to assemble these components is cumbersome: do '+'
characters get silently replaced with spaces? If a query parameter contains a '&', does that
get escaped? By offering methods to read and write individual query parameters directly,
application developers are saved from the hassles of encoding and decoding.
Plus a modern API
The URL (JDK1.0) and URI (Java 1.4) classes predate builders and instead use telescoping constructors. For example, there's no API to compose a URI with a custom port without also providing a query and fragment.
Instances of HttpUrl are well-formed and always have a scheme, host, and path. With
java.net.URL it's possible to create an awkward URL like http:/ with scheme and
path but no hostname. Building APIs that consume such malformed values is difficult!
This class has a modern API. It avoids punitive checked exceptions: get()
throws IllegalArgumentException on invalid input or parse()
returns null if the input is an invalid URL. You can even be explicit about whether each
component has been encoded already.
-
嵌套类概要
嵌套类 -
方法概要
修饰符和类型方法说明static intdefaultPort(String scheme) Returns 80 ifscheme.equals("http"), 443 ifscheme.equals("https")and -1 otherwise.Returns this URL's encoded fragment, like"abc"forhttp://host/#abc.Returns the password, or an empty string if none is set.Returns the entire path of this URL encoded for use in HTTP resource resolution.Returns a list of encoded path segments like["a", "b", "c"]for the URLhttp://host/a/b/c.Returns the query of this URL, encoded for use in HTTP resource resolution.Returns the username, or an empty string if none is set.booleanfragment()Returns this URL's fragment, like"abc"forhttp://host/#abc.static HttpUrlReturns a newHttpUrlrepresentingurl.static HttpUrlstatic HttpUrlinthashCode()host()Returns the host address suitable for use withInetAddress.getAllByName(String).booleanisHttps()newBuilder(String link) Returns a builder for the URL that would be retrieved by followinglinkfrom this URL, or null if the resulting URL is not well-formed.static HttpUrlReturns a newHttpUrlrepresentingurlif it is a well-formed HTTP or HTTPS URL, or null if it isn't.password()Returns the decoded password, or an empty string if none is present.Returns a list of path segments like["a", "b", "c"]for the URLhttp://host/a/b/c.intpathSize()Returns the number of segments in this URL's path.intport()Returns the explicitly-specified port if one was provided, or the default port for this URL's scheme.query()Returns this URL's query, like"abc"forhttp://host/?abc.queryParameter(String name) Returns the first query parameter namednamedecoded using UTF-8, or null if there is no such query parameter.queryParameterName(int index) Returns the name of the query parameter atindex.Returns the distinct query parameter names in this URL, like["a", "b"]forhttp://host/?a=apple&b=banana.queryParameterValue(int index) Returns the value of the query parameter atindex.queryParameterValues(String name) Returns all values for the query parameternameordered by their appearance in this URL.intReturns the number of query parameters in this URL, like 2 forhttp://host/?a=apple&b=banana.redact()Returns a string with containing this URL with its username, password, query, and fragment stripped, and its path replaced with/....Returns the URL that would be retrieved by followinglinkfrom this URL, or null if the resulting URL is not well-formed.scheme()Returns either "http" or "https".Returns the domain name of this URL'shost()that is one level beneath the public suffix by consulting the public suffix list.toString()uri()Returns this URL as ajava.net.URI.url()Returns this URL as ajava.net.URL.username()Returns the decoded username, or an empty string if none is present.
-
方法详细资料
-
defaultPort
Returns 80 ifscheme.equals("http"), 443 ifscheme.equals("https")and -1 otherwise. -
parse
Returns a newHttpUrlrepresentingurlif it is a well-formed HTTP or HTTPS URL, or null if it isn't. -
get
Returns a newHttpUrlrepresentingurl.- 抛出:
IllegalArgumentException- Ifurlis not a well-formed HTTP or HTTPS URL.
-
get
-
get
-
url
Returns this URL as ajava.net.URL. -
uri
Returns this URL as ajava.net.URI. BecauseURIis more strict than this class, the returned URI may be semantically different from this URL:- Characters forbidden by URI like
[and|will be escaped. - Invalid percent-encoded sequences like
%xxwill be encoded like%25xx. - Whitespace and control characters in the fragment will be stripped.
These differences may have a significant consequence when the URI is interpreted by a webserver. For this reason the URI class and this method should be avoided.
- Characters forbidden by URI like
-
scheme
Returns either "http" or "https". -
isHttps
public boolean isHttps() -
encodedUsername
Returns the username, or an empty string if none is set.URL encodedUsername()http://host/""http://username@host/"username"http://username:password@host/"username"http://a%20b:c%20d@host/"a%20b" -
username
Returns the decoded username, or an empty string if none is present.URL username()http://host/""http://username@host/"username"http://username:password@host/"username"http://a%20b:c%20d@host/"a b" -
encodedPassword
Returns the password, or an empty string if none is set.URL encodedPassword()http://host/""http://username@host/""http://username:password@host/"password"http://a%20b:c%20d@host/"c%20d" -
password
Returns the decoded password, or an empty string if none is present.URL password()http://host/""http://username@host/""http://username:password@host/"password"http://a%20b:c%20d@host/"c d" -
host
Returns the host address suitable for use withInetAddress.getAllByName(String). May be:- A regular host name, like
android.com. - An IPv4 address, like
127.0.0.1. - An IPv6 address, like
::1. Note that there are no square braces. - An encoded IDN, like
xn--n3h.net.
URL host()http://android.com/"android.com"http://127.0.0.1/"127.0.0.1"http://[::1]/"::1"http://xn--n3h.net/"xn--n3h.net" - A regular host name, like
-
port
public int port()Returns the explicitly-specified port if one was provided, or the default port for this URL's scheme. For example, this returns 8443 forhttps://square.com:8443/and 443 forhttps://square.com/. The result is in[1..65535].URL port()http://host/80http://host:8000/8000https://host/443 -
pathSize
public int pathSize()Returns the number of segments in this URL's path. This is also the number of slashes in the URL's path, like 3 inhttp://host/a/b/c. This is always at least 1.URL pathSize()http://host/1http://host/a/b/c3http://host/a/b/c/4 -
encodedPath
Returns the entire path of this URL encoded for use in HTTP resource resolution. The returned path will start with"/".URL encodedPath()http://host/"/"http://host/a/b/c"/a/b/c"http://host/a/b%20c/d"/a/b%20c/d" -
encodedPathSegments
Returns a list of encoded path segments like["a", "b", "c"]for the URLhttp://host/a/b/c. This list is never empty though it may contain a single empty string.URL encodedPathSegments()http://host/[""]http://host/a/b/c["a", "b", "c"]http://host/a/b%20c/d["a", "b%20c", "d"] -
pathSegments
Returns a list of path segments like["a", "b", "c"]for the URLhttp://host/a/b/c. This list is never empty though it may contain a single empty string.URL pathSegments()http://host/[""]http://host/a/b/c"["a", "b", "c"]http://host/a/b%20c/d"["a", "b c", "d"] -
encodedQuery
Returns the query of this URL, encoded for use in HTTP resource resolution. The returned string may be null (for URLs with no query), empty (for URLs with an empty query) or non-empty (all other URLs).URL encodedQuery()http://host/null http://host/?""http://host/?a=apple&k=key+lime"a=apple&k=key+lime"http://host/?a=apple&a=apricot"a=apple&a=apricot"http://host/?a=apple&b"a=apple&b" -
query
Returns this URL's query, like"abc"forhttp://host/?abc. Most callers should preferqueryParameterName(int)andqueryParameterValue(int)because these methods offer direct access to individual query parameters.URL query()http://host/null http://host/?""http://host/?a=apple&k=key+lime"a=apple&k=key lime"http://host/?a=apple&a=apricot"a=apple&a=apricot"http://host/?a=apple&b"a=apple&b" -
querySize
public int querySize()Returns the number of query parameters in this URL, like 2 forhttp://host/?a=apple&b=banana. If this URL has no query this returns 0. Otherwise it returns one more than the number of"&"separators in the query.URL querySize()http://host/0http://host/?1http://host/?a=apple&k=key+lime2http://host/?a=apple&a=apricot2http://host/?a=apple&b2 -
queryParameter
Returns the first query parameter namednamedecoded using UTF-8, or null if there is no such query parameter.URL queryParameter("a")http://host/null http://host/?null http://host/?a=apple&k=key+lime"apple"http://host/?a=apple&a=apricot"apple"http://host/?a=apple&b"apple" -
queryParameterNames
Returns the distinct query parameter names in this URL, like["a", "b"]forhttp://host/?a=apple&b=banana. If this URL has no query this returns the empty set.URL queryParameterNames()http://host/[]http://host/?[""]http://host/?a=apple&k=key+lime["a", "k"]http://host/?a=apple&a=apricot["a"]http://host/?a=apple&b["a", "b"] -
queryParameterValues
Returns all values for the query parameternameordered by their appearance in this URL. For example this returns["banana"]forqueryParameterValue("b")onhttp://host/?a=apple&b=banana.URL queryParameterValues("a")queryParameterValues("b")http://host/[][]http://host/?[][]http://host/?a=apple&k=key+lime["apple"][]http://host/?a=apple&a=apricot["apple", "apricot"][]http://host/?a=apple&b["apple"][null] -
queryParameterName
Returns the name of the query parameter atindex. For example this returns"a"forqueryParameterName(0)onhttp://host/?a=apple&b=banana. This throws ifindexis not less than the query size.URL queryParameterName(0)queryParameterName(1)http://host/exception exception http://host/?""exception http://host/?a=apple&k=key+lime"a""k"http://host/?a=apple&a=apricot"a""a"http://host/?a=apple&b"a""b" -
queryParameterValue
Returns the value of the query parameter atindex. For example this returns"apple"forqueryParameterName(0)onhttp://host/?a=apple&b=banana. This throws ifindexis not less than the query size.URL queryParameterValue(0)queryParameterValue(1)http://host/exception exception http://host/?null exception http://host/?a=apple&k=key+lime"apple""key lime"http://host/?a=apple&a=apricot"apple""apricot"http://host/?a=apple&b"apple"null -
encodedFragment
Returns this URL's encoded fragment, like"abc"forhttp://host/#abc. This returns null if the URL has no fragment.URL encodedFragment()http://host/null http://host/#""http://host/#abc"abc"http://host/#abc|def"abc|def" -
fragment
Returns this URL's fragment, like"abc"forhttp://host/#abc. This returns null if the URL has no fragment.URL fragment()http://host/null http://host/#""http://host/#abc"abc"http://host/#abc|def"abc|def" -
redact
Returns a string with containing this URL with its username, password, query, and fragment stripped, and its path replaced with/.... For example, redactinghttp://username:password@example.com/pathreturnshttp://example.com/.... -
resolve
Returns the URL that would be retrieved by followinglinkfrom this URL, or null if the resulting URL is not well-formed. -
newBuilder
-
newBuilder
Returns a builder for the URL that would be retrieved by followinglinkfrom this URL, or null if the resulting URL is not well-formed. -
equals
-
hashCode
public int hashCode() -
toString
-
topPrivateDomain
Returns the domain name of this URL'shost()that is one level beneath the public suffix by consulting the public suffix list. Returns null if this URL'shost()is an IP address or is considered a public suffix by the public suffix list.In general this method should not be used to test whether a domain is valid or routable. Instead, DNS is the recommended source for that information.
URL topPrivateDomain()http://google.com"google.com"http://adwords.google.co.uk"google.co.uk"http://squarenull http://co.uknull http://localhostnull http://127.0.0.1null
-