[英]Spring Data Rest Adding Link to Root - RepositoryLinksResource cannot be cast to Resource
我试图在我的API的根文档中添加一个自定义链接,遵循以下答案: 在Spring REST HATEOAS中使用RepositoryRestResource-s和常规控制器对root请求进行自定义响应
这是我的自定义资源处理器:
import org.springframework.data.rest.webmvc.RepositoryLinksResource;
import org.springframework.hateoas.Link;
import org.springframework.hateoas.ResourceProcessor;
import org.springframework.hateoas.mvc.ControllerLinkBuilder;
import org.springframework.stereotype.Component;
@Component
public class CustomRootLinksResourceProcessor implements ResourceProcessor<RepositoryLinksResource> {
@Override
public RepositoryLinksResource process(RepositoryLinksResource resource) {
Link link = ControllerLinkBuilder
.linkTo(ControllerLinkBuilder
.methodOn(CustomerController.class)
.register(null))
.withRel("registerCustomer");
resource.add(link);
return resource;
}
}
但是,当我查询我的API时,我收到以下异常
LOGBACK:19:01:03.425 [http-nio-8080-exec-2] ERROR o.s.d.r.w.RepositoryRestExceptionHandler - org.springframework.data.rest.webmvc.RepositoryLinksResource cannot be cast to org.springframework.hateoas.Resource
java.lang.ClassCastException: org.springframework.data.rest.webmvc.RepositoryLinksResource cannot be cast to org.springframework.hateoas.Resource
at org.springframework.hateoas.mvc.ResourceProcessorInvoker$DefaultProcessorWrapper.invokeProcessor(ResourceProcessorInvoker.java:224)
at org.springframework.hateoas.mvc.ResourceProcessorInvoker.invokeProcessorsFor(ResourceProcessorInvoker.java:141)
at org.springframework.hateoas.mvc.ResourceProcessorInvoker.invokeProcessorsFor(ResourceProcessorInvoker.java:124)
at org.springframework.hateoas.mvc.ResourceProcessorHandlerMethodReturnValueHandler.handleReturnValue(ResourceProcessorHandlerMethodReturnValueHandler.java:113)
at org.springframework.web.method.support.HandlerMethodReturnValueHandlerComposite.handleReturnValue(HandlerMethodReturnValueHandlerComposite.java:81)
at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:132)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:827)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:738)
at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85)
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:963)
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:897)
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:970)
at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:861)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:622)
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:846)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:230)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165)
我不确定我在这里做错了什么,因为检查ResourceProcessorInvoker的源代码它出现了只有一个转换为ResourceSupport
( RepositoryLinksResource
扩展,所以应该没问题)。 这是Spring数据休息中的错误还是我的CustomRootLinksResourceProcessor
有问题?
@Override
@SuppressWarnings("unchecked")
public Object invokeProcessor(Object object) {
return ((ResourceProcessor<ResourceSupport>) processor).process((ResourceSupport) object);
}
正如Sam所提到的那样(并且都归功于他) “ 我认为ResourceProcessor实现不能像文档中那样成为lambda ”
我无法在文档中找到确切的参考,但这是一个例子,以防万一其他人在解决这个问题。
这有效:
@Bean
public ResourceProcessor<Resource<Invoice>> processor() {
return new ResourceProcessor<Resource<Invoice>>() {
@Override
public Resource<Invoice> process(Resource<Invoice> resource) {
resource.add(entityLinks.linkToSingleResource(Invoice.class, 1));
return resource;
}
};
}
但这不是:
@Bean
public ResourceProcessor<Resource<Invoice>> processor() {
return (Resource<Invoice> resource) -> {
resource.add(entityLinks.linkToSingleResource(Invoice.class, 1));
return resource;
};
}
所以我在调试器中逐步完成了SDR代码,事实证明异常是由另一个ResourceProcessor
的调用引起的,如下所示:
@Component
public class CustomerResourceProcessorWrapper {
@Bean
public ResourceProcessor<Resource<Customer>> customerResourceProcessor() {
我仍然是Spring Data Rest的新手,所有这些都是反射魔法,但用straigt ResourceProcessor
替换错误的CustomerResourceProcessorWrapper
声明为我解决了这个问题:
@Component
public class CustomerResourceProcessor implements ResourceProcessor<Resource<Customer>> {
@Override
public Resource<Customer> process(Resource<Customer> resource) {
...
我仍然想知道这个包装器是什么以及为什么它不起作用...使用CustomerResourceProcessorWrapper
的相同代码工作正常,除非我添加CustomRootLinksResourceProcessor
。
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.