spring – 为具有复合ID的实体自定义HATEOAS链接生成
作者：互联网
我在PageAndSortingRepository上配置了RepositoryRestResource,它访问包含复合ID的实体：
@Entity
@IdClass(CustomerId.class)
public class Customer {
@Id BigInteger id;
@Id int startVersion;
...
}
public class CustomerId {
BigInteger id;
int startVersion;
...
}
@RepositoryRestResource(collectionResourceRel = "customers", path = "customers", itemResourceRel = "customers/{id}_{startVersion}")
public interface CustomerRepository extends PagingAndSortingRepository<Customer, CustomerId> {}
例如,当我在“http：//< server> / api / customers / 1_1”访问服务器时,我将正确的资源作为json返回,但是_links部分中的href是错误的,也是相同的对于我查询的任何其他客户：“http：//< server> / api / customer / 1”
即：
{
"id" : 1,
"startVersion" : 1,
...
"firstname" : "BOB",
"_links" : {
"self" : {
"href" : "http://localhost:9081/reps/api/reps/1" <-- This should be /1_1
}
}
}
我想这是因为我的复合ID,但我对如何更改此默认行为感到兴奋.
我已经看过ResourceSupport和ResourceProcessor类,但我不确定为了解决这个问题我需要更改多少.
知道春天的人能帮我一把吗？
解决方法:
不幸的是,所有Spring Data JPA / Rest版本高达2.1.0.RELEASE都无法满足您的需求.
源代码隐藏在Spring Data Commons / JPA中. Spring Data JPA仅支持Id和EmbeddedId作为标识符.
摘录JpaPersistentPropertyImpl：
static {
// [...]
annotations = new HashSet<Class<? extends Annotation>>();
annotations.add(Id.class);
annotations.add(EmbeddedId.class);
ID_ANNOTATIONS = annotations;
}
Spring Data Commons不支持组合属性的概念.它独立地对待一个类的每个属性.
当然,你可以破解Spring Data Rest.但这很麻烦,不能解决问题,降低框架的灵活性.
这是黑客攻击.这应该可以让您了解如何解决您的问题.
在您的配置中覆盖repositoryExporterHandlerAdapter并返回CustomPersistentEntityResourceAssemblerArgumentResolver.
另外,覆盖backendIdConverterRegistry并将CustomBackendIdConverter添加到已知id转换器的列表中：
import org.springframework.beans.factory.ListableBeanFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Import;
import org.springframework.data.rest.core.projection.ProxyProjectionFactory;
import org.springframework.data.rest.webmvc.RepositoryRestHandlerAdapter;
import org.springframework.data.rest.webmvc.config.RepositoryRestMvcConfiguration;
import org.springframework.data.rest.webmvc.spi.BackendIdConverter;
import org.springframework.data.rest.webmvc.support.HttpMethodHandlerMethodArgumentResolver;
import org.springframework.data.web.config.EnableSpringDataWebSupport;
import org.springframework.hateoas.ResourceProcessor;
import org.springframework.http.converter.HttpMessageConverter;
import org.springframework.plugin.core.OrderAwarePluginRegistry;
import org.springframework.plugin.core.PluginRegistry;
import org.springframework.web.method.support.HandlerMethodArgumentResolver;
import org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
@Configuration
@Import(RepositoryRestMvcConfiguration.class)
@EnableSpringDataWebSupport
public class RestConfig extends RepositoryRestMvcConfiguration {
@Autowired(required = false) List<ResourceProcessor<?>> resourceProcessors = Collections.emptyList();
@Autowired
ListableBeanFactory beanFactory;
@Override
@Bean
public PluginRegistry<BackendIdConverter, Class<?>> backendIdConverterRegistry() {
List<BackendIdConverter> converters = new ArrayList<BackendIdConverter>(3);
converters.add(new CustomBackendIdConverter());
converters.add(BackendIdConverter.DefaultIdConverter.INSTANCE);
return OrderAwarePluginRegistry.create(converters);
}
@Bean
public RequestMappingHandlerAdapter repositoryExporterHandlerAdapter() {
List<HttpMessageConverter<?>> messageConverters = defaultMessageConverters();
configureHttpMessageConverters(messageConverters);
RepositoryRestHandlerAdapter handlerAdapter = new RepositoryRestHandlerAdapter(defaultMethodArgumentResolvers(),
resourceProcessors);
handlerAdapter.setMessageConverters(messageConverters);
return handlerAdapter;
}
private List<HandlerMethodArgumentResolver> defaultMethodArgumentResolvers()
{
CustomPersistentEntityResourceAssemblerArgumentResolver peraResolver = new CustomPersistentEntityResourceAssemblerArgumentResolver(
repositories(), entityLinks(), config().projectionConfiguration(), new ProxyProjectionFactory(beanFactory));
return Arrays.asList(pageableResolver(), sortResolver(), serverHttpRequestMethodArgumentResolver(),
repoRequestArgumentResolver(), persistentEntityArgumentResolver(),
resourceMetadataHandlerMethodArgumentResolver(), HttpMethodHandlerMethodArgumentResolver.INSTANCE,
peraResolver, backendIdHandlerMethodArgumentResolver());
}
}
创建CustomBackendIdConverter.此类负责呈现您的自定义实体ID：
import org.springframework.data.rest.webmvc.spi.BackendIdConverter;
import java.io.Serializable;
public class CustomBackendIdConverter implements BackendIdConverter {
@Override
public Serializable fromRequestId(String id, Class<?> entityType) {
return id;
}
@Override
public String toRequestId(Serializable id, Class<?> entityType) {
if(entityType.equals(Customer.class)) {
Customer c = (Customer) id;
return c.getId() + "_" +c.getStartVersion();
}
return id.toString();
}
@Override
public boolean supports(Class<?> delimiter) {
return true;
}
}
CustomPersistentEntityResourceAssemblerArgumentResolver反过来应该返回一个CustomPersistentEntityResourceAssembler：
import org.springframework.core.MethodParameter;
import org.springframework.data.repository.support.Repositories;
import org.springframework.data.rest.core.projection.ProjectionDefinitions;
import org.springframework.data.rest.core.projection.ProjectionFactory;
import org.springframework.data.rest.webmvc.PersistentEntityResourceAssembler;
import org.springframework.data.rest.webmvc.config.PersistentEntityResourceAssemblerArgumentResolver;
import org.springframework.data.rest.webmvc.support.PersistentEntityProjector;
import org.springframework.hateoas.EntityLinks;
import org.springframework.web.bind.support.WebDataBinderFactory;
import org.springframework.web.context.request.NativeWebRequest;
import org.springframework.web.method.support.ModelAndViewContainer;
public class CustomPersistentEntityResourceAssemblerArgumentResolver extends PersistentEntityResourceAssemblerArgumentResolver {
private final Repositories repositories;
private final EntityLinks entityLinks;
private final ProjectionDefinitions projectionDefinitions;
private final ProjectionFactory projectionFactory;
public CustomPersistentEntityResourceAssemblerArgumentResolver(Repositories repositories, EntityLinks entityLinks,
ProjectionDefinitions projectionDefinitions, ProjectionFactory projectionFactory) {
super(repositories, entityLinks,projectionDefinitions,projectionFactory);
this.repositories = repositories;
this.entityLinks = entityLinks;
this.projectionDefinitions = projectionDefinitions;
this.projectionFactory = projectionFactory;
}
public boolean supportsParameter(MethodParameter parameter) {
return PersistentEntityResourceAssembler.class.isAssignableFrom(parameter.getParameterType());
}
public Object resolveArgument(MethodParameter parameter, ModelAndViewContainer mavContainer,
NativeWebRequest webRequest, WebDataBinderFactory binderFactory) throws Exception {
String projectionParameter = webRequest.getParameter(projectionDefinitions.getParameterName());
PersistentEntityProjector projector = new PersistentEntityProjector(projectionDefinitions, projectionFactory,
projectionParameter);
return new CustomPersistentEntityResourceAssembler(repositories, entityLinks, projector);
}
}
CustomPersistentEntityResourceAssembler需要覆盖getSelfLinkFor.正如您所看到的,entity.getIdProperty()返回Customer类的id或startVersion属性,后者又用于在BeanWrapper的帮助下检索实际值.这里我们使用instanceof运算符来短路整个框架.因此,您的Customer类应实现Serializable以进行进一步处理.
import org.springframework.data.mapping.PersistentEntity;
import org.springframework.data.mapping.model.BeanWrapper;
import org.springframework.data.repository.support.Repositories;
import org.springframework.data.rest.webmvc.PersistentEntityResourceAssembler;
import org.springframework.data.rest.webmvc.support.Projector;
import org.springframework.hateoas.EntityLinks;
import org.springframework.hateoas.Link;
import org.springframework.util.Assert;
public class CustomPersistentEntityResourceAssembler extends PersistentEntityResourceAssembler {
private final Repositories repositories;
private final EntityLinks entityLinks;
public CustomPersistentEntityResourceAssembler(Repositories repositories, EntityLinks entityLinks, Projector projector) {
super(repositories, entityLinks, projector);
this.repositories = repositories;
this.entityLinks = entityLinks;
}
public Link getSelfLinkFor(Object instance) {
Assert.notNull(instance, "Domain object must not be null!");
Class<? extends Object> instanceType = instance.getClass();
PersistentEntity<?, ?> entity = repositories.getPersistentEntity(instanceType);
if (entity == null) {
throw new IllegalArgumentException(String.format("Cannot create self link for %s! No persistent entity found!",
instanceType));
}
Object id;
//this is a hack for demonstration purpose. don't do this at home!
if(instance instanceof Customer) {
id = instance;
} else {
BeanWrapper<Object> wrapper = BeanWrapper.create(instance, null);
id = wrapper.getProperty(entity.getIdProperty());
}
Link resourceLink = entityLinks.linkToSingleResource(entity.getType(), id);
return new Link(resourceLink.getHref(), Link.REL_SELF);
}
}
而已！你应该看到这个URI：
{
"_embedded" : {
"customers" : [ {
"name" : "test",
"_links" : {
"self" : {
"href" : "http://localhost:8080/demo/customers/1_1"
}
}
} ]
}
}
Imho,如果你正在开展一个绿色的田野项目,我建议完全抛弃IdClass并使用基于Long class的技术简单ID.这是使用Spring Data Rest 2.1.0.RELEASE,Spring数据JPA 1.6.0.RELEASE和Spring Framework 4.0.3.RELEASE测试的.
标签：spring,spring-data-jpa,spring-mvc,spring-hateoas 来源： https://codeday.me/bug/20190926/1821997.html