使用 RestTemplate 反序列化 JSON 数组
Deserialising JSON array using RestTemplate
我正在尝试使用 Rest 模板将 JSON 数据转换为 java class。
JSON数据的格式是这样的，不能更改：
{
"items":[
{
"id":"5818",
"seconds_since_report":21,
"latitude":34.0954089,
"run_id":"78_411_1",
"predictable":true,
"route_id":"78",
"heading":271.0,
"longitude":-118.152489
},
{
"id":"5819",
"seconds_since_report":48,
"latitude":33.9197757,
"run_id":"260_267_1",
"predictable":true,
"route_id":"260",
"heading":199.0,
"longitude":-118.1880995
},
{
"id":"5813",
"seconds_since_report":21,
"latitude":34.134002,
"run_id":"181_191_0",
"predictable":true,
"route_id":"181",
"heading":101.0,
"longitude":-118.209497
}
]
}
保存数据的javaclass为：
public class Items {
private Collection<Vehicle> items;
public Collection<Vehicle> getItems() {
return items;
}
public void setItems(Collection<Vehicle> items) {
this.items = items;
}
}
import com.fasterxml.jackson.annotation.JsonFormat;
@JsonFormat(shape=JsonFormat.Shape.ARRAY)
public class Vehicle {
private String id;
private String run_id;
private String route_id;
private Double latitude;
private Double longitude;
private boolean predictable;
private int seconds_since_report;
private Double heading;
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getRun_id() {
return run_id;
}
public void setRun_id(String run_id) {
this.run_id = run_id;
}
public String getRoute_id() {
return route_id;
}
public void setRoute_id(String route_id) {
this.route_id = route_id;
}
public Double getLatitude() {
return latitude;
}
public void setLatitude(Double latitude) {
this.latitude = latitude;
}
public Double getLongitude() {
return longitude;
}
public void setLongitude(Double longitude) {
this.longitude = longitude;
}
public boolean isPredictable() {
return predictable;
}
public void setPredictable(boolean predictable) {
this.predictable = predictable;
}
public int getSeconds_since_report() {
return seconds_since_report;
}
public void setSeconds_since_report(int seconds_since_report) {
this.seconds_since_report = seconds_since_report;
}
public Double getHeading() {
return heading;
}
public void setHeading(Double heading) {
this.heading = heading;
}
}
要接收 JSON 数据并反序列化我正在做的事情：
RestTemplate restTemplate = new RestTemplate();
ResponseEntity<Items> data = restTemplate.getForEntity(url, Items.class);
但是我遇到了这个异常：
org.springframework.web.client.RestClientException: Error while extracting response for type [class com.es.projectbackend.model.Items] and content type [application/json]; nested exception is org.springframework.http.converter.HttpMessageNotReadableException: JSON parse error: Cannot deserialize a POJO (of type com.es.projectbackend.model.Vehicle) from non-Array representation (token: START_OBJECT): type/property designed to be serialized as JSON Array; nested exception is com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot deserialize a POJO (of type com.es.projectbackend.model.Vehicle) from non-Array representation (token: START_OBJECT): type/property designed to be serialized as JSON Array
at [Source: (PushbackInputStream); line: 1, column: 12] (through reference chain: com.es.projectbackend.model.Items["items"]->java.util.ArrayList[0])
at org.springframework.web.client.HttpMessageConverterExtractor.extractData(HttpMessageConverterExtractor.java:120) ~[spring-web-5.3.5.jar:5.3.5]
at org.springframework.web.client.RestTemplate$ResponseEntityResponseExtractor.extractData(RestTemplate.java:1037) ~[spring-web-5.3.5.jar:5.3.5]
at org.springframework.web.client.RestTemplate$ResponseEntityResponseExtractor.extractData(RestTemplate.java:1020) ~[spring-web-5.3.5.jar:5.3.5]
at org.springframework.web.client.RestTemplate.doExecute(RestTemplate.java:778) ~[spring-web-5.3.5.jar:5.3.5]
at org.springframework.web.client.RestTemplate.execute(RestTemplate.java:711) ~[spring-web-5.3.5.jar:5.3.5]
at org.springframework.web.client.RestTemplate.getForEntity(RestTemplate.java:361) ~[spring-web-5.3.5.jar:5.3.5]
at com.es.projectbackend.service.LAMetroService.updateLAMetroVehicles(LAMetroService.java:57) ~[classes/:?]
at jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:?]
at jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:64) ~[?:?]
at jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:?]
at java.lang.reflect.Method.invoke(Method.java:564) ~[?:?]
at org.springframework.scheduling.support.ScheduledMethodRunnable.run(ScheduledMethodRunnable.java:84) ~[spring-context-5.3.5.jar:5.3.5]
at org.springframework.scheduling.support.DelegatingErrorHandlingRunnable.run(DelegatingErrorHandlingRunnable.java:54) [spring-context-5.3.5.jar:5.3.5]
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:515) [?:?]
at java.util.concurrent.FutureTask.runAndReset(FutureTask.java:305) [?:?]
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:305) [?:?]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1130) [?:?]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:630) [?:?]
at java.lang.Thread.run(Thread.java:832) [?:?]
Caused by: org.springframework.http.converter.HttpMessageNotReadableException: JSON parse error: Cannot deserialize a POJO (of type com.es.projectbackend.model.Vehicle) from non-Array representation (token: START_OBJECT): type/property designed to be serialized as JSON Array; nested exception is com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot deserialize a POJO (of type com.es.projectbackend.model.Vehicle) from non-Array representation (token: START_OBJECT): type/property designed to be serialized as JSON Array
at [Source: (PushbackInputStream); line: 1, column: 12] (through reference chain: com.es.projectbackend.model.Items["items"]->java.util.ArrayList[0])
at org.springframework.http.converter.json.AbstractJackson2HttpMessageConverter.readJavaType(AbstractJackson2HttpMessageConverter.java:389) ~[spring-web-5.3.5.jar:5.3.5]
at org.springframework.http.converter.json.AbstractJackson2HttpMessageConverter.read(AbstractJackson2HttpMessageConverter.java:342) ~[spring-web-5.3.5.jar:5.3.5]
at org.springframework.web.client.HttpMessageConverterExtractor.extractData(HttpMessageConverterExtractor.java:105) ~[spring-web-5.3.5.jar:5.3.5]
... 18 more
Caused by: com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot deserialize a POJO (of type com.es.projectbackend.model.Vehicle) from non-Array representation (token: START_OBJECT): type/property designed to be serialized as JSON Array
at [Source: (PushbackInputStream); line: 1, column: 12] (through reference chain: com.es.projectbackend.model.Items["items"]->java.util.ArrayList[0])
at com.fasterxml.jackson.databind.exc.MismatchedInputException.from(MismatchedInputException.java:59) ~[jackson-databind-2.11.4.jar:2.11.4]
at com.fasterxml.jackson.databind.DeserializationContext.reportInputMismatch(DeserializationContext.java:1468) ~[jackson-databind-2.11.4.jar:2.11.4]
at com.fasterxml.jackson.databind.DeserializationContext.handleUnexpectedToken(DeserializationContext.java:1242) ~[jackson-databind-2.11.4.jar:2.11.4]
at com.fasterxml.jackson.databind.deser.impl.BeanAsArrayDeserializer._deserializeFromNonArray(BeanAsArrayDeserializer.java:373) ~[jackson-databind-2.11.4.jar:2.11.4]
at com.fasterxml.jackson.databind.deser.impl.BeanAsArrayDeserializer.deserialize(BeanAsArrayDeserializer.java:103) ~[jackson-databind-2.11.4.jar:2.11.4]
at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.deserialize(CollectionDeserializer.java:290) ~[jackson-databind-2.11.4.jar:2.11.4]
at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.deserialize(CollectionDeserializer.java:249) ~[jackson-databind-2.11.4.jar:2.11.4]
at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.deserialize(CollectionDeserializer.java:26) ~[jackson-databind-2.11.4.jar:2.11.4]
at com.fasterxml.jackson.databind.deser.impl.MethodProperty.deserializeAndSet(MethodProperty.java:129) ~[jackson-databind-2.11.4.jar:2.11.4]
at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserializeFromObject(BeanDeserializer.java:371) ~[jackson-databind-2.11.4.jar:2.11.4]
at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserialize(BeanDeserializer.java:164) ~[jackson-databind-2.11.4.jar:2.11.4]
at com.fasterxml.jackson.databind.ObjectMapper._readMapAndClose(ObjectMapper.java:4526) ~[jackson-databind-2.11.4.jar:2.11.4]
at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:3521) ~[jackson-databind-2.11.4.jar:2.11.4]
at org.springframework.http.converter.json.AbstractJackson2HttpMessageConverter.readJavaType(AbstractJackson2HttpMessageConverter.java:378) ~[spring-web-5.3.5.jar:5.3.5]
at org.springframework.http.converter.json.AbstractJackson2HttpMessageConverter.read(AbstractJackson2HttpMessageConverter.java:342) ~[spring-web-5.3.5.jar:5.3.5]
at org.springframework.web.client.HttpMessageConverterExtractor.extractData(HttpMessageConverterExtractor.java:105) ~[spring-web-5.3.5.jar:5.3.5]
... 18 more
我以前做过这个并且成功了，但是 JSON 数据的格式略有不同。但是这次我无法理解这个错误。
首先，移除@JsonFormat(shape=JsonFormat.Shape.ARRAY)
其次，将默认的空构造函数添加到 类
注解 @JsonFormat(shape=JsonFormat.Shape.ARRAY) 让 Jackson 寻找 Vehicle class 的数组表示。
可能看起来像这样：
{
"items":[
[
"5818",
21,
34.0954089,
"78_411_1",
true,
"78",
271.0,
-118.152489
]
]
}
变量的顺序需要匹配class属性的顺序。这就是 Shape.ARRAY 正在做的事情。
您可能想要的是实际的对象表示。因此，只需删除 @JsonFormat(shape=JsonFormat.Shape.ARRAY) 即可。
我正在尝试使用 Rest 模板将 JSON 数据转换为 java class。
JSON数据的格式是这样的，不能更改：
{
"items":[
{
"id":"5818",
"seconds_since_report":21,
"latitude":34.0954089,
"run_id":"78_411_1",
"predictable":true,
"route_id":"78",
"heading":271.0,
"longitude":-118.152489
},
{
"id":"5819",
"seconds_since_report":48,
"latitude":33.9197757,
"run_id":"260_267_1",
"predictable":true,
"route_id":"260",
"heading":199.0,
"longitude":-118.1880995
},
{
"id":"5813",
"seconds_since_report":21,
"latitude":34.134002,
"run_id":"181_191_0",
"predictable":true,
"route_id":"181",
"heading":101.0,
"longitude":-118.209497
}
]
}
保存数据的javaclass为：
public class Items {
private Collection<Vehicle> items;
public Collection<Vehicle> getItems() {
return items;
}
public void setItems(Collection<Vehicle> items) {
this.items = items;
}
}
import com.fasterxml.jackson.annotation.JsonFormat;
@JsonFormat(shape=JsonFormat.Shape.ARRAY)
public class Vehicle {
private String id;
private String run_id;
private String route_id;
private Double latitude;
private Double longitude;
private boolean predictable;
private int seconds_since_report;
private Double heading;
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getRun_id() {
return run_id;
}
public void setRun_id(String run_id) {
this.run_id = run_id;
}
public String getRoute_id() {
return route_id;
}
public void setRoute_id(String route_id) {
this.route_id = route_id;
}
public Double getLatitude() {
return latitude;
}
public void setLatitude(Double latitude) {
this.latitude = latitude;
}
public Double getLongitude() {
return longitude;
}
public void setLongitude(Double longitude) {
this.longitude = longitude;
}
public boolean isPredictable() {
return predictable;
}
public void setPredictable(boolean predictable) {
this.predictable = predictable;
}
public int getSeconds_since_report() {
return seconds_since_report;
}
public void setSeconds_since_report(int seconds_since_report) {
this.seconds_since_report = seconds_since_report;
}
public Double getHeading() {
return heading;
}
public void setHeading(Double heading) {
this.heading = heading;
}
}
要接收 JSON 数据并反序列化我正在做的事情：
RestTemplate restTemplate = new RestTemplate();
ResponseEntity<Items> data = restTemplate.getForEntity(url, Items.class);
但是我遇到了这个异常：
org.springframework.web.client.RestClientException: Error while extracting response for type [class com.es.projectbackend.model.Items] and content type [application/json]; nested exception is org.springframework.http.converter.HttpMessageNotReadableException: JSON parse error: Cannot deserialize a POJO (of type com.es.projectbackend.model.Vehicle) from non-Array representation (token: START_OBJECT): type/property designed to be serialized as JSON Array; nested exception is com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot deserialize a POJO (of type com.es.projectbackend.model.Vehicle) from non-Array representation (token: START_OBJECT): type/property designed to be serialized as JSON Array
at [Source: (PushbackInputStream); line: 1, column: 12] (through reference chain: com.es.projectbackend.model.Items["items"]->java.util.ArrayList[0])
at org.springframework.web.client.HttpMessageConverterExtractor.extractData(HttpMessageConverterExtractor.java:120) ~[spring-web-5.3.5.jar:5.3.5]
at org.springframework.web.client.RestTemplate$ResponseEntityResponseExtractor.extractData(RestTemplate.java:1037) ~[spring-web-5.3.5.jar:5.3.5]
at org.springframework.web.client.RestTemplate$ResponseEntityResponseExtractor.extractData(RestTemplate.java:1020) ~[spring-web-5.3.5.jar:5.3.5]
at org.springframework.web.client.RestTemplate.doExecute(RestTemplate.java:778) ~[spring-web-5.3.5.jar:5.3.5]
at org.springframework.web.client.RestTemplate.execute(RestTemplate.java:711) ~[spring-web-5.3.5.jar:5.3.5]
at org.springframework.web.client.RestTemplate.getForEntity(RestTemplate.java:361) ~[spring-web-5.3.5.jar:5.3.5]
at com.es.projectbackend.service.LAMetroService.updateLAMetroVehicles(LAMetroService.java:57) ~[classes/:?]
at jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:?]
at jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:64) ~[?:?]
at jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:?]
at java.lang.reflect.Method.invoke(Method.java:564) ~[?:?]
at org.springframework.scheduling.support.ScheduledMethodRunnable.run(ScheduledMethodRunnable.java:84) ~[spring-context-5.3.5.jar:5.3.5]
at org.springframework.scheduling.support.DelegatingErrorHandlingRunnable.run(DelegatingErrorHandlingRunnable.java:54) [spring-context-5.3.5.jar:5.3.5]
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:515) [?:?]
at java.util.concurrent.FutureTask.runAndReset(FutureTask.java:305) [?:?]
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:305) [?:?]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1130) [?:?]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:630) [?:?]
at java.lang.Thread.run(Thread.java:832) [?:?]
Caused by: org.springframework.http.converter.HttpMessageNotReadableException: JSON parse error: Cannot deserialize a POJO (of type com.es.projectbackend.model.Vehicle) from non-Array representation (token: START_OBJECT): type/property designed to be serialized as JSON Array; nested exception is com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot deserialize a POJO (of type com.es.projectbackend.model.Vehicle) from non-Array representation (token: START_OBJECT): type/property designed to be serialized as JSON Array
at [Source: (PushbackInputStream); line: 1, column: 12] (through reference chain: com.es.projectbackend.model.Items["items"]->java.util.ArrayList[0])
at org.springframework.http.converter.json.AbstractJackson2HttpMessageConverter.readJavaType(AbstractJackson2HttpMessageConverter.java:389) ~[spring-web-5.3.5.jar:5.3.5]
at org.springframework.http.converter.json.AbstractJackson2HttpMessageConverter.read(AbstractJackson2HttpMessageConverter.java:342) ~[spring-web-5.3.5.jar:5.3.5]
at org.springframework.web.client.HttpMessageConverterExtractor.extractData(HttpMessageConverterExtractor.java:105) ~[spring-web-5.3.5.jar:5.3.5]
... 18 more
Caused by: com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot deserialize a POJO (of type com.es.projectbackend.model.Vehicle) from non-Array representation (token: START_OBJECT): type/property designed to be serialized as JSON Array
at [Source: (PushbackInputStream); line: 1, column: 12] (through reference chain: com.es.projectbackend.model.Items["items"]->java.util.ArrayList[0])
at com.fasterxml.jackson.databind.exc.MismatchedInputException.from(MismatchedInputException.java:59) ~[jackson-databind-2.11.4.jar:2.11.4]
at com.fasterxml.jackson.databind.DeserializationContext.reportInputMismatch(DeserializationContext.java:1468) ~[jackson-databind-2.11.4.jar:2.11.4]
at com.fasterxml.jackson.databind.DeserializationContext.handleUnexpectedToken(DeserializationContext.java:1242) ~[jackson-databind-2.11.4.jar:2.11.4]
at com.fasterxml.jackson.databind.deser.impl.BeanAsArrayDeserializer._deserializeFromNonArray(BeanAsArrayDeserializer.java:373) ~[jackson-databind-2.11.4.jar:2.11.4]
at com.fasterxml.jackson.databind.deser.impl.BeanAsArrayDeserializer.deserialize(BeanAsArrayDeserializer.java:103) ~[jackson-databind-2.11.4.jar:2.11.4]
at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.deserialize(CollectionDeserializer.java:290) ~[jackson-databind-2.11.4.jar:2.11.4]
at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.deserialize(CollectionDeserializer.java:249) ~[jackson-databind-2.11.4.jar:2.11.4]
at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.deserialize(CollectionDeserializer.java:26) ~[jackson-databind-2.11.4.jar:2.11.4]
at com.fasterxml.jackson.databind.deser.impl.MethodProperty.deserializeAndSet(MethodProperty.java:129) ~[jackson-databind-2.11.4.jar:2.11.4]
at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserializeFromObject(BeanDeserializer.java:371) ~[jackson-databind-2.11.4.jar:2.11.4]
at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserialize(BeanDeserializer.java:164) ~[jackson-databind-2.11.4.jar:2.11.4]
at com.fasterxml.jackson.databind.ObjectMapper._readMapAndClose(ObjectMapper.java:4526) ~[jackson-databind-2.11.4.jar:2.11.4]
at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:3521) ~[jackson-databind-2.11.4.jar:2.11.4]
at org.springframework.http.converter.json.AbstractJackson2HttpMessageConverter.readJavaType(AbstractJackson2HttpMessageConverter.java:378) ~[spring-web-5.3.5.jar:5.3.5]
at org.springframework.http.converter.json.AbstractJackson2HttpMessageConverter.read(AbstractJackson2HttpMessageConverter.java:342) ~[spring-web-5.3.5.jar:5.3.5]
at org.springframework.web.client.HttpMessageConverterExtractor.extractData(HttpMessageConverterExtractor.java:105) ~[spring-web-5.3.5.jar:5.3.5]
... 18 more
我以前做过这个并且成功了，但是 JSON 数据的格式略有不同。但是这次我无法理解这个错误。
首先，移除@JsonFormat(shape=JsonFormat.Shape.ARRAY)
其次，将默认的空构造函数添加到 类
注解 @JsonFormat(shape=JsonFormat.Shape.ARRAY) 让 Jackson 寻找 Vehicle class 的数组表示。
可能看起来像这样：
{
"items":[
[
"5818",
21,
34.0954089,
"78_411_1",
true,
"78",
271.0,
-118.152489
]
]
}
变量的顺序需要匹配class属性的顺序。这就是 Shape.ARRAY 正在做的事情。
您可能想要的是实际的对象表示。因此，只需删除 @JsonFormat(shape=JsonFormat.Shape.ARRAY) 即可。