我有一对多的关系黑白酒店和房间实体。数据流如下：
我在下面的junit测试中模拟了上面的流程，并运行到下面显示的异常中。
Method: POST
URI: http://localhost:49515/api/hotels
Request Body: {"id":100,"name":"hotel1"
Method: POST
URI: http://localhost:49515/api/rooms
Request Body: {"id":200,"name":"room1","hotel":100}
o.s.d.r.w.RepositoryRestExceptionHandler : Could not read document: Failed to convert from type [java.net.URI] to type [com.example.entities.Hotel] for value '100'; nested exception is java.lang.IllegalArgumentException: Cannot resolve URI 100. Is it local or remote? Only local URIs are resolvable. (through reference chain: com.example.entities.Room["hotel"]); nested exception is com.fasterxml.jackson.databind.JsonMappingException:
问题似乎是在发布Room对象创建时，对Hotel的引用将作为纯ID字段发送（在序列化期间），并且Jackson在反序列化期间无法解析该引用。如何发送酒店的URI而不是其ID？
{"id":200,"name":"room1", "hotel": "http://localhost:49515/api/hotels/100"}
而不是
{"id":200,"name":"room1", "hotel":100}
有没有其他方法可以解决我的数据流？
以下示例代码：
@Entity
@Table
@JsonIdentityInfo(generator=ObjectIdGenerators.PropertyGenerator.class, property="id")
public class Hotel implements Serializable {
private static final long serialVersionUID = 1L;
@Id
@GeneratedValue(strategy= GenerationType.AUTO)
private Integer id;
private String name;
@OneToMany(mappedBy="hotel")
@JsonIgnore
private Set<Room> rooms;
public Hotel() {
}
// --- getters and setters omitted for brevity ---
}
@Entity
@Table
@JsonIdentityInfo(generator=ObjectIdGenerators.PropertyGenerator.class, property="id")
public class Room implements Serializable {
private static final long serialVersionUID = 1L;
@Id
@GeneratedValue(strategy= GenerationType.AUTO)
private Integer id;
@ManyToOne(fetch= FetchType.LAZY)
@JsonIdentityReference(alwaysAsId=true)
private Hotel hotel;
public Room() {
}
// --- getters and setters omitted for brevity ---
}
public interface HotelRepo extends JpaRepository<Hotel, Integer> {
}
public interface RoomRepo extends JpaRepository<Room, Integer> {
}
@RunWith(SpringRunner.class)
@SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
@AutoConfigureTestDatabase(connection = EmbeddedDatabaseConnection.H2)
public class JPACreationTester {
static final String CREATE_HOTEL_URL = "/api/hotels";
static final String CREATE_ROOM_URL = "/api/rooms";
@Autowired
private TestRestTemplate restTemplate;
@Test
public void testDataCreation () throws Exception {
String resName1 = "hotel1";
Hotel hotel1 = new Hotel(resName1);
hotel1.setId(100);
String roomName1 = "room1";
Room room1 = new Room(roomName1);
room1.setId(200);
room1.setHotel(hotel1);
Set<Room> rooms = new HashSet<>();
rooms.add(room1);
hotel1.setRooms(rooms);
Hotel hotel1saved = this.restTemplate.postForObject(CREATE_HOTEL_URL, hotel1, Hotel.class);
Room room1saved = this.restTemplate.postForObject(CREATE_ROOM_URL, room1, Room.class);
assertThat(room1saved).as("Rooms are equal").isEqualToIgnoringNullFields(room1);
assertThat(hotel1saved).as("Hotels are equal").isEqualToIgnoringNullFields(hotel1);
}
}
下面的服务器日志
2017-01-13 11:51:47.969 DEBUG 1217 --- [ main] o.s.web.client.RestTemplate : Created POST request for "http://localhost:49515/api/hotels"
2017-01-13 11:51:48.073 DEBUG 1217 --- [ main] o.s.web.client.RestTemplate : Setting request Accept header to [application/json, application/json, application/*+json, application/*+json]
2017-01-13 11:51:48.090 DEBUG 1217 --- [ main] o.s.web.client.RestTemplate : Writing [com.example.entities.Hotel@1d9bd1d6] using [org.springframework.http.converter.json.MappingJackson2HttpMessageConverter@10bdfbcc]
Method: POST
URI: http://localhost:49515/api/hotels
Request Body: {"id":100,"name":"hotel1"}
Response body: java.io.ByteArrayInputStream@23708f14
2017-01-13 11:51:48.653 DEBUG 1217 --- [ main] o.s.web.client.RestTemplate : POST request for "http://localhost:49515/api/hotels" resulted in 201 (null)
2017-01-13 11:51:48.655 DEBUG 1217 --- [ main] o.s.web.client.RestTemplate : Reading [class com.example.entities.Hotel] as "application/json;charset=UTF-8" using [org.springframework.http.converter.json.MappingJackson2HttpMessageConverter@10bdfbcc]
2017-01-13 11:51:48.656 DEBUG 1217 --- [ main] o.s.web.client.RestTemplate : Created POST request for "http://localhost:49515/api/rooms"
2017-01-13 11:51:48.659 DEBUG 1217 --- [ main] o.s.web.client.RestTemplate : Setting request Accept header to [application/json, application/json, application/*+json, application/*+json]
2017-01-13 11:51:48.660 DEBUG 1217 --- [ main] o.s.web.client.RestTemplate : Writing [com.example.entities.Room@151659dd] using [org.springframework.http.converter.json.MappingJackson2HttpMessageConverter@10bdfbcc]
Method: POST
URI: http://localhost:49515/api/rooms
Request Body: {"id":200,"hotel":100,"name":"room1"}
2017-01-13 11:51:48.697 ERROR 1217 --- [o-auto-1-exec-2] o.s.d.r.w.RepositoryRestExceptionHandler : Could not read document: Failed to convert from type [java.net.URI] to type [com.example.entities.Hotel] for value '100'; nested exception is java.lang.IllegalArgumentException: Cannot resolve URI 100. Is it local or remote? Only local URIs are resolvable. (through reference chain: com.example.entities.Room["hotel"]); nested exception is com.fasterxml.jackson.databind.JsonMappingException: Failed to convert from type [java.net.URI] to type [com.example.entities.Hotel] for value '100'; nested exception is java.lang.IllegalArgumentException: Cannot resolve URI 100. Is it local or remote? Only local URIs are resolvable. (through reference chain: com.example.entities.Room["hotel"])
org.springframework.http.converter.HttpMessageNotReadableException: Could not read document: Failed to convert from type [java.net.URI] to type [com.example.entities.Hotel] for value '100'; nested exception is java.lang.IllegalArgumentException: Cannot resolve URI 100. Is it local or remote? Only local URIs are resolvable. (through reference chain: com.example.entities.Room["hotel"]); nested exception is com.fasterxml.jackson.databind.JsonMappingException: Failed to convert from type [java.net.URI] to type [com.example.entities.Hotel] for value '100'; nested exception is java.lang.IllegalArgumentException: Cannot resolve URI 100. Is it local or remote? Only local URIs are resolvable. (through reference chain: com.example.entities.Room["hotel"])
at org.springframework.http.converter.json.AbstractJackson2HttpMessageConverter.readJavaType(AbstractJackson2HttpMessageConverter.java:240) ~[spring-web-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.springframework.http.converter.json.AbstractJackson2HttpMessageConverter.readInternal(AbstractJackson2HttpMessageConverter.java:217) ~[spring-web-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.springframework.http.converter.AbstractHttpMessageConverter.read(AbstractHttpMessageConverter.java:193) ~[spring-web-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.springframework.data.rest.webmvc.config.PersistentEntityResourceHandlerMethodArgumentResolver.read(PersistentEntityResourceHandlerMethodArgumentResolver.java:228) ~[spring-data-rest-webmvc-2.5.6.RELEASE.jar:na]
at org.springframework.data.rest.webmvc.config.PersistentEntityResourceHandlerMethodArgumentResolver.read(PersistentEntityResourceHandlerMethodArgumentResolver.java:185) ~[spring-data-rest-webmvc-2.5.6.RELEASE.jar:na]
at org.springframework.data.rest.webmvc.config.PersistentEntityResourceHandlerMethodArgumentResolver.resolveArgument(PersistentEntityResourceHandlerMethodArgumentResolver.java:138) ~[spring-data-rest-webmvc-2.5.6.RELEASE.jar:na]
at org.springframework.web.method.support.HandlerMethodArgumentResolverComposite.resolveArgument(HandlerMethodArgumentResolverComposite.java:121) ~[spring-web-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.springframework.web.method.support.InvocableHandlerMethod.getMethodArgumentValues(InvocableHandlerMethod.java:160) ~[spring-web-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:129) ~[spring-web-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:116) ~[spring-webmvc-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:827) ~[spring-webmvc-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:738) ~[spring-webmvc-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85) ~[spring-webmvc-4.3.5.RELEASE.jar:4.3.5.RELEASE]
答案 0 :(得分：0)
对初始POST的响应将包含标题“位置”，它将为您提供新创建的酒店的URI：例如
HTTP/1.1 201 Created
Server: Apache-Coyote/1.1
Location: http://localhost:49515/api/hotels/100
Content-Length: 0
Date: Wed, 26 Feb 2014 20:26:55 GMT
然后，您应该能够完全按照建议使用“位置”标题的值来发布到/ rooms端点：
{
"id":200,
"name":"room1",
"hotel": "http://localhost:49515/api/hotels/100"
}