我希望我的回复包括:
"keyMaps":{
"href":"http://localhost/api/keyMaps{/keyMapId}",
"templated":true
}
这很容易实现:
add(new Link("http://localhost/api/keyMaps{/keyMapId}", "keyMaps"));
但是,当然,我宁愿使用ControllerLinkBuilder,如下所示:
add(linkTo(methodOn(KeyMapController.class).getKeyMap("{keyMapId}")).withRel("keyMaps"));
问题是,当变量“{keyMapId}”到达UriTemplate构造函数时,它已被包含在编码的URL中:
http://localhost/api/keyMaps/%7BkeyMapId%7D
因此UriTemplate的构造函数不会将其识别为包含变量。
如何说服我想使用模板变量的ControllerLinkBuilder?
答案 0 :(得分:8)
在我看来,Spring-HATEOAS的当前状态不允许通过ControllerLinkBuilder
(我非常希望被证明是错误的),所以我自己使用以下类实现了这个用于模板化查询参数:
public class TemplatedLinkBuilder {
private static final TemplatedLinkBuilderFactory FACTORY = new TemplatedLinkBuilderFactory();
public static final String ENCODED_LEFT_BRACE = "%7B";
public static final String ENCODED_RIGHT_BRACE = "%7D";
private UriComponentsBuilder uriComponentsBuilder;
TemplatedLinkBuilder(UriComponentsBuilder builder) {
uriComponentsBuilder = builder;
}
public static TemplatedLinkBuilder linkTo(Object invocationValue) {
return FACTORY.linkTo(invocationValue);
}
public static <T> T methodOn(Class<T> controller, Object... parameters) {
return DummyInvocationUtils.methodOn(controller, parameters);
}
public Link withRel(String rel) {
return new Link(replaceTemplateMarkers(uriComponentsBuilder.build().toString()), rel);
}
public Link withSelfRel() {
return withRel(Link.REL_SELF);
}
private String replaceTemplateMarkers(String encodedUri) {
return encodedUri.replaceAll(ENCODED_LEFT_BRACE, "{").replaceAll(ENCODED_RIGHT_BRACE, "}");
}
}
和
public class TemplatedLinkBuilderFactory {
private final ControllerLinkBuilderFactory controllerLinkBuilderFactory;
public TemplatedLinkBuilderFactory() {
this.controllerLinkBuilderFactory = new ControllerLinkBuilderFactory();
}
public TemplatedLinkBuilder linkTo(Object invocationValue) {
ControllerLinkBuilder controllerLinkBuilder = controllerLinkBuilderFactory.linkTo(invocationValue);
UriComponentsBuilder uriComponentsBuilder = controllerLinkBuilder.toUriComponentsBuilder();
Assert.isInstanceOf(DummyInvocationUtils.LastInvocationAware.class, invocationValue);
DummyInvocationUtils.LastInvocationAware invocations = (DummyInvocationUtils.LastInvocationAware) invocationValue;
DummyInvocationUtils.MethodInvocation invocation = invocations.getLastInvocation();
Object[] arguments = invocation.getArguments();
MethodParameters parameters = new MethodParameters(invocation.getMethod());
for (MethodParameter requestParameter : parameters.getParametersWith(RequestParam.class)) {
Object value = arguments[requestParameter.getParameterIndex()];
if (value == null) {
uriComponentsBuilder.queryParam(requestParameter.getParameterName(), "{" + requestParameter.getParameterName() + "}");
}
}
return new TemplatedLinkBuilder(uriComponentsBuilder);
}
}
嵌入普通的ControllerLinkBuilder然后使用类似的逻辑来解析为空的@RequestParam
带注释的参数,并将这些参数添加到查询参数中。此外,我们的客户端重新使用这些模板化的URI来执行对服务器的进一步请求。为了实现这一点而不需要担心剥离未使用的模板化参数,我必须执行相反的操作(使用{params}
交换null
),我正在使用自定义Spring {{1如下
RequestParamMethodArgumentResolver
此外,这需要替换我使用的现有public class TemplatedRequestParamResolver extends RequestParamMethodArgumentResolver {
public TemplatedRequestParamResolver() {
super(false);
}
@Override
protected Object resolveName(String name, MethodParameter parameter, NativeWebRequest webRequest) throws Exception {
Object value = super.resolveName(name, parameter, webRequest);
if (value instanceof Object[]) {
Object[] valueAsCollection = (Object[])value;
List<Object> resultList = new LinkedList<Object>();
for (Object collectionEntry : valueAsCollection) {
if (nullifyTemplatedValue(collectionEntry) != null) {
resultList.add(collectionEntry);
}
}
if (resultList.isEmpty()) {
value = null;
} else {
value = resultList.toArray();
}
} else{
value = nullifyTemplatedValue(value);
}
return value;
}
private Object nullifyTemplatedValue(Object value) {
if (value != null && value.toString().startsWith("{") && value.toString().endsWith("}")) {
value = null;
}
return value;
}
}
:
RequestParamMethodArgumentResolver
很遗憾,虽然@Configuration
public class ConfigureTemplatedRequestParamResolver {
private @Autowired RequestMappingHandlerAdapter adapter;
@PostConstruct
public void replaceArgumentMethodHandlers() {
List<HandlerMethodArgumentResolver> argumentResolvers = new ArrayList<HandlerMethodArgumentResolver>(adapter.getArgumentResolvers());
for (int cursor = 0; cursor < argumentResolvers.size(); ++cursor) {
HandlerMethodArgumentResolver handlerMethodArgumentResolver = argumentResolvers.get(cursor);
if (handlerMethodArgumentResolver instanceof RequestParamMethodArgumentResolver) {
argumentResolvers.remove(cursor);
argumentResolvers.add(cursor, new TemplatedRequestParamResolver());
break;
}
}
adapter.setArgumentResolvers(argumentResolvers);
}
}
和{
是模板化 URI中的有效字符,但它们在URI中无效,这可能是您的客户端代码依赖的问题它有多严格。我更喜欢Spring-HATEOAS内置的整洁解决方案!
答案 1 :(得分:6)
使用spring-hateoas
的最新版本,您可以执行以下操作:
UriComponents uriComponents = UriComponentsBuilder.fromUri(linkBuilder.toUri()).build();
UriTemplate template = new UriTemplate(uriComponents.toUriString())
.with("keyMapId", TemplateVariable.SEGMENT);
会给你:http://localhost:8080/bla{/keyMapId}",
答案 2 :(得分:5)
我们遇到了同样的问题。一般的解决方法是我们有自己的LinkBuilder类和一堆静态助手。模板化的看起来像这样:
public static Link linkToSubcategoriesTemplated(String categoryId){
return new Link(
new UriTemplate(
linkTo(methodOn(CategoryController.class).subcategories(null, null, categoryId))
.toUriComponentsBuilder().build().toUriString(),
// register it as variable
getBaseTemplateVariables()
),
REL_SUBCATEGORIES
);
}
private static TemplateVariables getBaseTemplateVariables() {
return new TemplateVariables(
new TemplateVariable("page", TemplateVariable.VariableType.REQUEST_PARAM),
new TemplateVariable("sort", TemplateVariable.VariableType.REQUEST_PARAM),
new TemplateVariable("size", TemplateVariable.VariableType.REQUEST_PARAM)
);
}
这是为了公开PagedResource的控制器响应的参数。
然后在控制器中我们称之为根据需要添加一个withRel。
答案 3 :(得分:4)
根据this issue comment,这将在即将发布的spring-hateoas中得到解决。
目前,Maven Central中的ControllerLinkBuilder
可以直接替换de.escalon.hypermedia:spring-hateoas-ext
。
我现在可以这样做:
import static de.escalon.hypermedia.spring.AffordanceBuilder.*
...
add(linkTo(methodOn(KeyMapController.class).getKeyMap(null)).withRel("keyMaps"));
我传入null
作为参数值,表示我想使用模板变量。变量名称将自动从控制器中提取。
答案 4 :(得分:3)
从此提交开始:
https://github.com/spring-projects/spring-hateoas/commit/2daf8aabfb78b6767bf27ac3e473832c872302c7
您现在可以传递null
预期路径变量的位置。它对我有用,没有解决方法。
resource.add(linkTo(methodOn(UsersController.class).someMethod(null)).withRel("someMethod"));
结果:
"someMethod": {
"href": "http://localhost:8080/api/v1/users/{userId}",
"templated": true
},
同时检查相关问题:https://github.com/spring-projects/spring-hateoas/issues/545
答案 5 :(得分:2)
我需要在spring数据休息应用程序的根目录中包含一个带有模板变量的链接,以便通过traverson访问oauth2令牌。这很好用,也许很有用:
@Component
class RepositoryLinksResourceProcessor implements ResourceProcessor<RepositoryLinksResource> {
@Override
RepositoryLinksResource process(RepositoryLinksResource resource) {
UriTemplate uriTemplate = new UriTemplate(
ControllerLinkBuilder.
linkTo(
TokenEndpoint,
TokenEndpoint.getDeclaredMethod("postAccessToken", java.security.Principal, Map )).
toUriComponentsBuilder().
build().
toString(),
new TemplateVariables([
new TemplateVariable("username", TemplateVariable.VariableType.REQUEST_PARAM),
new TemplateVariable("password", TemplateVariable.VariableType.REQUEST_PARAM),
new TemplateVariable("clientId", TemplateVariable.VariableType.REQUEST_PARAM),
new TemplateVariable("clientSecret", TemplateVariable.VariableType.REQUEST_PARAM)
])
)
resource.add(
new Link( uriTemplate,
"token"
)
)
return resource
}
}
答案 6 :(得分:0)
基于之前的评论,我已经实现了一个通用的帮助方法(针对spring-hateoas-0.20.0)作为“临时”解决方法。该实现仅考虑RequestParameters,并且远未经过优化或经过充分测试。对于沿着同一个兔子洞行进的其他一些可怜的灵魂来说,它可能会派上用场:
public static Link getTemplatedLink(final Method m, final String rel) {
DefaultParameterNameDiscoverer disco = new DefaultParameterNameDiscoverer();
ControllerLinkBuilder builder = ControllerLinkBuilder.linkTo(m.getDeclaringClass(), m);
UriTemplate uriTemplate = new UriTemplate(UriComponentsBuilder.fromUri(builder.toUri()).build().toUriString());
Annotation[][] parameterAnnotations = m.getParameterAnnotations();
int param = 0;
for (Annotation[] parameterAnnotation : parameterAnnotations) {
for (Annotation annotation : parameterAnnotation) {
if (annotation.annotationType().equals(RequestParam.class)) {
RequestParam rpa = (RequestParam) annotation;
String parameterName = rpa.name();
if (StringUtils.isEmpty(parameterName)) parameterName = disco.getParameterNames(m)[param];
uriTemplate = uriTemplate.with(parameterName, TemplateVariable.VariableType.REQUEST_PARAM);
}
}
param++;
}
return new Link(uriTemplate, rel);
}