javax.ws.rs.core.Link Maven / Gradle / Ivy
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package javax.ws.rs.core;
import java.lang.reflect.Method;
import java.net.URI;
import java.util.Arrays;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import javax.ws.rs.Path;
import javax.ws.rs.Produces;
import javax.ws.rs.ext.RuntimeDelegate;
import javax.ws.rs.ext.RuntimeDelegate.HeaderDelegate;
import javax.xml.bind.annotation.XmlAnyAttribute;
import javax.xml.bind.annotation.XmlAttribute;
import javax.xml.bind.annotation.adapters.XmlAdapter;
import javax.xml.namespace.QName;
/**
* Class representing hypermedia links. A hypermedia link may include additional
* parameters beyond its underlying URI. Parameters such as "rel" or "type"
* provide additional meta-data and can be used to create instances of
* {@link javax.ws.rs.client.Invocation.Builder} in order to follow links.
*
* The methods {@link #toString} and {@link #valueOf} can be used to serialize
* and de-serialize a link into a link header (RFC 5988).
*
* @author Marek Potociar
* @author Santiago Pericas-Geertsen
* @see javax.ws.rs.client.Client#invocation
* @since 2.0
*/
public final class Link {
/**
* Title link param from RFC 5988.
*/
public static final String TITLE = "title";
/**
* Rel link param from RFC 5988.
*/
public static final String REL = "rel";
/**
* Type link param from RFC 5988.
*/
public static final String TYPE = "type";
/**
* The underlying link URI.
*/
private URI uri;
/**
* A map for all the link parameters such as "rel", "type", etc.
*/
private Map map = new HashMap();
/**
* Underlying implementation delegate to serialize as link header.
*/
private static final HeaderDelegate delegate =
RuntimeDelegate.getInstance().createHeaderDelegate(Link.class);
/**
* Returns the underlying URI associated with this link.
*
* @return underlying URI.
*/
public URI getUri() {
return uri;
}
/**
* Convenience method that returns a {@link javax.ws.rs.core.UriBuilder}
* initialized with this link's underlying URI.
*
* @return UriBuilder initialized using underlying URI.
*/
public UriBuilder getUriBuilder() {
return UriBuilder.fromUri(uri);
}
/**
* Returns the value associated with the link "rel" param, or
* {@code null} if this param is not specified.
*
* @return relation types as string or {@code null}.
*/
public String getRel() {
return map.get(REL);
}
/**
* Returns the value associated with the link "rel" param as a list
* of strings or the empty list if "rel" is not defined.
*
* @return relation types as list of strings or empty list.
*/
public List getRels() {
final String rels = map.get(REL);
return rels == null ? Collections.emptyList() : Arrays.asList(rels.split(" +"));
}
/**
* Returns the value associated with the link "title" param, or
* {@code null} if this param is not specified.
*
* @return value of "title" parameter or {@code null}.
*/
public String getTitle() {
return map.get(TITLE);
}
/**
* Returns the value associated with the link "type" param, or
* {@code null} if this param is not specified.
*
* @return value of "type" parameter or {@code null}.
*/
public String getType() {
return map.get(TYPE);
}
/**
* Returns an immutable map that includes all the link parameters
* defined on this link. If defined, this map will include entries
* for "rel", "title" and "type".
*
* @return immutable map of link parameters.
*/
public Map getParams() {
return new HashMap(map);
}
/**
* Equality test for links.
*
* @param other Object to compare against.
* @return {@code true} if equal, {@code false} otherwise.
*/
@Override
public boolean equals(Object other) {
if (this == other) {
return true;
}
if (other instanceof Link) {
final Link otherLink = (Link) other;
return uri.equals(otherLink.uri) && map.equals(otherLink.map);
}
return false;
}
/**
* Hash code computation for links.
*
* @return Hash code for this link.
*/
@Override
public int hashCode() {
int hash = 3;
hash = 89 * hash + (this.uri != null ? this.uri.hashCode() : 0);
hash = 89 * hash + (this.map != null ? this.map.hashCode() : 0);
return hash;
}
/**
* Returns a string representation as a link header (RFC 5988).
* All link params are serialized as link-param="value" where value
* is a quoted-string. For example,
*
* ; title="employee"; rel="manager friend"
*
* @return string link header representation for this link.
*/
@Override
public String toString() {
return delegate.toString(this);
}
/**
* Simple parser to convert link header string representations into a link.
*
* link ::= '<' uri '>' (';' link-param)*
* link-param ::= name '=' quoted-string
*
*
* See RFC 5988 for more information.
*
* @param value String representation.
* @return newly parsed link.
* @throws IllegalArgumentException if a syntax error is found.
*/
public static Link valueOf(String value) throws IllegalArgumentException {
return delegate.fromString(value);
}
/**
* Create a new builder instance initialized from an existing URI.
*
* @param uri a URI that will be used to initialize the builder.
* @return a new builder.
* @throws IllegalArgumentException if uri is {@code null}.
*/
public static Builder fromUri(URI uri) throws IllegalArgumentException {
Builder b = new Builder();
b.uri(uri);
return b;
}
/**
* Create a new builder instance initialized from an existing URI
* represented as a string.
*
* @param uri a URI that will be used to initialize the builder.
* @return a new builder.
* @throws IllegalArgumentException if uri is {@code null}.
*/
public static Builder fromUri(String uri) throws IllegalArgumentException {
Builder b = new Builder();
b.uri(uri);
return b;
}
/**
* Create a new builder instance initialized from another link.
*
* @param link other link used for initialization.
* @return a new builder.
* @since 2.0
*/
public static Builder fromLink(Link link) {
Builder b = new Builder();
b.uri(link.uri);
b.link.map = new HashMap(link.map);
return b;
}
/**
* Generate a link by introspecting a resource method. This method is a shorthand
* for {@code fromResourceMethod(resource, method, method)} where the method
* name is used as the value of the "rel" parameter.
*
* @param resource resource class.
* @param method name of resource method.
* @return link builder to further configure link.
* @throws IllegalArgumentException if any argument is {@code null} or no method is found.
* @see Link#fromResourceMethod(java.lang.Class, java.lang.String, java.lang.String)
*/
public static Builder fromResourceMethod(Class resource, String method)
throws IllegalArgumentException {
return fromResourceMethod(resource, method, method);
}
/**
* Generate a link by introspecting a resource method. Finds the first method
* of a given name and generates a link with the appropriate URI and values
* for "type" and "rel".
* The value of "type" is set to be the first media-type in {@code @Produces},
* and is omitted if that annotation is not present on the method. The value
* of "rel" must be specified as an argument to this method.
*
* @param resource resource class.
* @param method name of resource method.
* @param rel value of {@code "rel"} parameter.
* @return link builder to further configure link.
* @throws IllegalArgumentException if any argument is {@code null} or no method is found.
*/
public static Builder fromResourceMethod(Class resource, String method, String rel)
throws IllegalArgumentException {
if (resource == null || method == null || rel == null) {
throw new IllegalArgumentException("All parameters must be non-null");
}
Builder lb = Link.fromUri(UriBuilder.fromResource(resource).build());
lb.rel(rel);
Method[] methods = resource.getMethods();
for (Method m : methods) {
if (m.getName().equals(method)) {
final Path path = m.getAnnotation(Path.class);
if (path != null) {
lb.path(m);
}
final Produces ps = m.getAnnotation(Produces.class);
if (ps != null) {
final String[] values = ps.value();
if (values.length > 0) {
lb.type(values[0]); // use first type
}
}
return lb;
}
}
throw new IllegalArgumentException("Method '" + method + "' not found in class '"
+ resource.getName() + "'");
}
/**
* Builder class for hypermedia links.
*
* @see Link
* @since 2.0
*/
public static class Builder {
/**
* Link being built by the builder.
*/
private Link link = new Link();
/**
* Underlying builder for link's URI.
*/
private UriBuilder uriBuilder;
/**
* Set underlying URI template for the link being constructed.
*
* @param uri underlying URI for link
* @return the updated builder.
*/
public Builder uri(URI uri) {
uriBuilder = UriBuilder.fromUri(uri);
return this;
}
/**
* Set underlying string representing URI template for the link being
* constructed.
*
* @param uri underlying URI for link.
* @return the updated builder.
* @throws IllegalArgumentException if string representation of URI is invalid.
*/
public Builder uri(String uri) throws IllegalArgumentException {
uriBuilder = UriBuilder.fromUri(uri);
return this;
}
/**
* Convenience method to set a link relation. More than one "rel" value can
* be specified by using one or more whitespace characters as delimiters
* according to RFC 5988. The effect of calling this method is cumulative;
* relations are appended using a single space character as separator.
*
* @param rel relation name.
* @return the updated builder.
* @throws IllegalArgumentException if the name is {@code null}.
*/
public Builder rel(String rel) {
final String rels = link.map.get(REL);
param(REL, rels == null ? rel : rels + " " + rel);
return this;
}
/**
* Convenience method to set a "title" on this link.
*
* @param title title parameter of this link.
* @return the updated builder.
* @throws IllegalArgumentException if the title is {@code null}.
*/
public Builder title(String title) {
param(TITLE, title);
return this;
}
/**
* Convenience method to set a "type" on this link.
*
* @param type type parameter of this link.
* @return the updated builder.
* @throws IllegalArgumentException if the type is {@code null}.
*/
public Builder type(String type) {
param(TYPE, type);
return this;
}
/**
* Set an arbitrary parameter on this link.
*
* @param name the name of the parameter.
* @param value the value set for the parameter.
* @return the updated builder.
* @throws IllegalArgumentException if either the name or value are {@code null}.
*/
public Builder param(String name, String value) throws IllegalArgumentException {
if (name == null || value == null) {
throw new IllegalArgumentException("Link parameter name or value is null");
}
link.map.put(name, value);
return this;
}
/**
* Finish building this link and return the instance.
*
* @return newly built link.
* @throws IllegalArgumentException if there are any URI template parameters
* without a supplied value.
* @throws UriBuilderException if a URI cannot be constructed based on the
* current state of the builder.
*/
public Link build() {
link.uri = uriBuilder.build();
return link;
}
/**
* Finish building this link using the supplied values as URI parameters.
*
* @param values parameters used to build underlying URI.
* @return the updated builder.
* @throws IllegalArgumentException if there are any URI template parameters
* without a supplied value, or if a value is {@code null}.
* @throws UriBuilderException if a URI cannot be constructed based on the
* current state of the underlying URI builder.
*/
public Link build(Object... values) throws UriBuilderException {
link.uri = uriBuilder.build(values);
return link;
}
/**
* Adds a path to the existing URI builder. For internal use only.
*
* @param method method from which to get path.
* @return the updated builder.
*/
private Builder path(Method method) {
uriBuilder.path(method);
return this;
}
}
/**
* Value type for {@link javax.ws.rs.core.Link} that can be marshalled and
* unmarshalled by JAXB.
*
* @see javax.ws.rs.core.Link.JaxbAdapter
* @since 2.0
*/
public static class JaxbLink {
private URI uri;
private Map params;
public JaxbLink() {
}
public JaxbLink(URI uri) {
this.uri = uri;
}
public JaxbLink(URI uri, Map params) {
this.uri = uri;
this.params = params;
}
@XmlAttribute(name = "href")
public URI getUri() {
return uri;
}
@XmlAnyAttribute
public Map getParams() {
if (params == null) {
params = new HashMap();
}
return params;
}
}
/**
* An implementation of JAXB {@link javax.xml.bind.annotation.adapters.XmlAdapter}
* that maps the JAX-RS {@link javax.ws.rs.core.Link} type to a value that can be
* marshalled and unmarshalled by JAXB.
*
* @see javax.ws.rs.core.Link.JaxbLink
* @since 2.0
*/
public static class JaxbAdapter extends XmlAdapter {
@Override
public Link unmarshal(JaxbLink v) throws Exception {
Link.Builder lb = Link.fromUri(v.getUri());
for (Entry e : v.getParams().entrySet()) {
lb.param(e.getKey().getLocalPart(), e.getValue().toString());
}
return lb.build();
}
@Override
public JaxbLink marshal(Link v) throws Exception {
JaxbLink jl = new JaxbLink(v.getUri());
for (Entry e : v.getParams().entrySet()) {
final String name = e.getKey();
jl.getParams().put(new QName("", name), e.getValue());
}
return jl;
}
}
}