我使用Springboot和RestTemplate来解析JSON。我正在寻找处理数组的所有资源，但我知道数组需要括号（[]）。
我这里有JSON（https://rsbuddy.com/exchange/summary.json）
（链接断开时的简短示例）
{"2": {"overall_average": 216, "sp": 5, "members": true, "buy_average": 215,
"sell_average": 215, "name": "Cannonball", "id": 2}, "6": {"overall_average":
173518, "sp": 187500, "members": true, "buy_average": 190176, "sell_average":
189343, "name": "Cannon base", "id": 6}, ... ,
"12287": {"overall_average": 0,
"sp": 5200, "members": false, "buy_average": 3234, "sell_average": 3234,
"name": "Mithril platebody (t)", "id": 12287}}
感觉它应该是一个数组，因为它是一个列表，但它没有括号，并且无法使用以下代码进行解析：
public List<ItemSummaryContainer> consumeItems() {
ResponseEntity<List<ItemSummaryContainer>> itemSummaryResponse =
restTemplate.exchange(url, HttpMethod.GET, null, new ParameterizedTypeReference<List<ItemSummaryContainer>>() {
});
return itemSummaryResponse.getBody();
}
ItemSummaryContainer类
@JsonIgnoreProperties(ignoreUnknown = true)
public class ItemSummaryContainer {
private int id;
private ItemSummary itemSummary;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public ItemSummary getItemSummary() {
return itemSummary;
}
public void setItemSummary(ItemSummary itemSummary) {
this.itemSummary = itemSummary;
}
}
ItemSummary类
@JsonIgnoreProperties(ignoreUnknown = true)
public class ItemSummary {
private Integer id;
private String name;
private Integer members;
public ItemSummary() {
}
public ItemSummary(Integer id, String name, Integer members) {
super();
this.id = id;
this.name = name;
this.members = members;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getMembers() {
return members;
}
public void setMembers(int members) {
this.members = members;
}
@Override
public boolean equals(Object obj) {
if (this == obj)
return true;
if (obj == null)
return false;
if (getClass() != obj.getClass())
return false;
ItemSummary other = (ItemSummary) obj;
if (id != other.id)
return false;
if (members != other.members)
return false;
if (name == null) {
if (other.name != null)
return false;
} else if (!name.equals(other.name))
return false;
return true;
}
}
堆栈跟踪
java.lang.IllegalStateException: Failed to execute CommandLineRunner
at org.springframework.boot.SpringApplication.callRunner(SpringApplication.java:801) [spring-boot-1.4.0.RELEASE.jar:1.4.0.RELEASE]
at org.springframework.boot.SpringApplication.callRunners(SpringApplication.java:782) [spring-boot-1.4.0.RELEASE.jar:1.4.0.RELEASE]
at org.springframework.boot.SpringApplication.afterRefresh(SpringApplication.java:769) [spring-boot-1.4.0.RELEASE.jar:1.4.0.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:314) [spring-boot-1.4.0.RELEASE.jar:1.4.0.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1185) [spring-boot-1.4.0.RELEASE.jar:1.4.0.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1174) [spring-boot-1.4.0.RELEASE.jar:1.4.0.RELEASE]
at com.tjwhalen.game.Application.main(Application.java:50) [classes/:na]
Caused by: org.springframework.http.converter.HttpMessageNotReadableException: Could not read document: Can not deserialize instance of java.util.ArrayList out of START_OBJECT token
at [Source: java.io.PushbackInputStream@55f8669d; line: 1, column: 1]; nested exception is com.fasterxml.jackson.databind.JsonMappingException: Can not deserialize instance of java.util.ArrayList out of START_OBJECT token
at [Source: java.io.PushbackInputStream@55f8669d; line: 1, column: 1]
at org.springframework.http.converter.json.AbstractJackson2HttpMessageConverter.readJavaType(AbstractJackson2HttpMessageConverter.java:228) ~[spring-web-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at org.springframework.http.converter.json.AbstractJackson2HttpMessageConverter.read(AbstractJackson2HttpMessageConverter.java:213) ~[spring-web-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at org.springframework.web.client.HttpMessageConverterExtractor.extractData(HttpMessageConverterExtractor.java:95) ~[spring-web-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at org.springframework.web.client.RestTemplate$ResponseEntityResponseExtractor.extractData(RestTemplate.java:884) ~[spring-web-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at org.springframework.web.client.RestTemplate$ResponseEntityResponseExtractor.extractData(RestTemplate.java:868) ~[spring-web-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at org.springframework.web.client.RestTemplate.doExecute(RestTemplate.java:622) ~[spring-web-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at org.springframework.web.client.RestTemplate.execute(RestTemplate.java:580) ~[spring-web-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at org.springframework.web.client.RestTemplate.exchange(RestTemplate.java:526) ~[spring-web-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at com.tjwhalen.game.service.dao.ItemSummaryURLConsumer.consumeItems(ItemSummaryURLConsumer.java:25) ~[classes/:na]
at com.tjwhalen.game.service.impl.ItemSummaryRestServiceImpl.getItems(ItemSummaryRestServiceImpl.java:25) ~[classes/:na]
at com.tjwhalen.game.loader.LoadItems.load(LoadItems.java:38) ~[classes/:na]
at com.tjwhalen.game.loader.LoaderRunner.execute(LoaderRunner.java:26) ~[classes/:na]
at com.tjwhalen.game.Application$AppConfig.run(Application.java:78) ~[classes/:na]
at org.springframework.boot.SpringApplication.callRunner(SpringApplication.java:798) [spring-boot-1.4.0.RELEASE.jar:1.4.0.RELEASE]
... 6 common frames omitted
Caused by: com.fasterxml.jackson.databind.JsonMappingException: Can not deserialize instance of java.util.ArrayList out of START_OBJECT token
at [Source: java.io.PushbackInputStream@55f8669d; line: 1, column: 1]
at com.fasterxml.jackson.databind.JsonMappingException.from(JsonMappingException.java:261) ~[jackson-databind-2.8.1.jar:2.8.1]
at com.fasterxml.jackson.databind.DeserializationContext.reportMappingException(DeserializationContext.java:1233) ~[jackson-databind-2.8.1.jar:2.8.1]
at com.fasterxml.jackson.databind.DeserializationContext.handleUnexpectedToken(DeserializationContext.java:1121) ~[jackson-databind-2.8.1.jar:2.8.1]
at com.fasterxml.jackson.databind.DeserializationContext.handleUnexpectedToken(DeserializationContext.java:1074) ~[jackson-databind-2.8.1.jar:2.8.1]
at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.handleNonArray(CollectionDeserializer.java:328) ~[jackson-databind-2.8.1.jar:2.8.1]
at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.deserialize(CollectionDeserializer.java:259) ~[jackson-databind-2.8.1.jar:2.8.1]
at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.deserialize(CollectionDeserializer.java:249) ~[jackson-databind-2.8.1.jar:2.8.1]
at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.deserialize(CollectionDeserializer.java:26) ~[jackson-databind-2.8.1.jar:2.8.1]
at com.fasterxml.jackson.databind.ObjectMapper._readMapAndClose(ObjectMapper.java:3789) ~[jackson-databind-2.8.1.jar:2.8.1]
at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:2913) ~[jackson-databind-2.8.1.jar:2.8.1]
at org.springframework.http.converter.json.AbstractJackson2HttpMessageConverter.readJavaType(AbstractJackson2HttpMessageConverter.java:225) ~[spring-web-4.3.2.RELEASE.jar:4.3.2.RELEASE]
... 19 common frames omitted
请提出建议，或提出任何必要的澄清问题，
由于
答案 0 :(得分：3)
您尝试解析的JSON完全有效。它不是一个数组，但它仍然有效：
{
"2": {
"overall_average": 211,
"buy_average": 208,
"members": true,
"id": 2,
"name": "Cannonball",
"sell_average": 210,
"sp": 5
},
"6": {
"overall_average": 0,
"buy_average": 0,
"members": true,
"id": 6,
"name": "Cannon base",
"sell_average": 0,
"sp": 187500
},
"12289": {
"overall_average": 9999,
"buy_average": 0,
"members": false,
"id": 12289,
"name": "Mithril platelegs (t)",
"sell_average": 9999,
"sp": 2600
},
...
}
ItemSummary类可以定义如下：
@JsonIgnoreProperties(ignoreUnknown = true)
public class ItemSummary {
private String id;
private String name;
private boolean members;
// Getters and setters omitted
}
整个JSON可以解析为Map<String, ItemSummary>。请参阅下面的详细信息。
Map<String, ItemSummary> 使用Spring REST模板，使用：
RestTemplate restTemplate = new RestTemplate();
ResponseEntity<Map<String, ItemSummary>> response =
restTemplate.exchange(
"https://rsbuddy.com/exchange/summary.json",
HttpMethod.GET,
null,
new ParameterizedTypeReference<Map<String, ItemSummary>>() {});
Map<String, ItemSummary> map = response.getBody();
使用杰克逊的ObjectMapper，您可以：
ObjectMapper mapper = new ObjectMapper();
Map<String, ItemSummary> map =
mapper.readValue(new URL("https://rsbuddy.com/exchange/summary.json"),
new TypeReference<Map<String, ItemSummary>>() {});
Map<String, ItemSummary>包装到类如果您需要围绕Map<String, ItemSummary>的包装类，请将其定义如下：
@JsonIgnoreProperties(ignoreUnknown = true)
public class ItemSummaryContainer {
private Map<String, ItemSummary> items;
@JsonCreator
public ItemSummaryContainer(Map<String, ItemSummary> items) {
this.items = items;
}
// Getters and setters omitted
}
使用Spring REST模板，使用：
RestTemplate restTemplate = new RestTemplate();
ResponseEntity<ItemSummaryContainer> response =
restTemplate.exchange(
"https://rsbuddy.com/exchange/summary.json",
HttpMethod.GET,
null,
new ParameterizedTypeReference<ItemSummaryContainer>() {});
ItemSummaryContainer container = response.getBody();
对于杰克逊的ObjectMapper，你会有：
ObjectMapper mapper = new ObjectMapper();
ItemSummaryContainer container =
mapper.readValue(new URL("https://rsbuddy.com/exchange/summary.json"),
ItemSummaryContainer.class);
答案 1 :(得分：1)
JSON和JAVA类之间的不匹配。
哪个在你的范围内？ JSON还是Java？修复其中任何一个并根据Json更改Java类，反之亦然。
你的JSON：
{
"2" : {
"members" : true,
"sell_average" : 207,
"id" : 2,
"buy_average" : 206,
"sp" : 5,
"name" : "Cannonball",
"overall_average" : 209
},
"6" : {
"members
.....
根据您的描述，预计会有Java object，而不是LIST。
如果无法更改JSON输入，请将您的java类与
匹配@JsonIgnoreProperties(ignoreUnknown = true)
public class ItemSummaryContainer {
private Map<Integer, ItemSummary> items;
// getter and setter
}
如果是另一方，请更改您的JSON。