背景：

项目中使用jackson反序列化工作时出现了Can not deserialize instance of相关的异常，现在针对出现的几种情况做一个小小的总结。

（1）Cannot deserialize instance of `com.ysl.test.bo.Street` out of START_ARRAY token

public class AddressList {private List<Street> streetLine;private String city;private String state;private String postalCode;private String county;private String countryCode;}

@Data
public class AddressObject {private Street streetLine;private String city;private String state;private String postalCode;private String county;private String countryCode;}

测试方法：

@Testpublic void test1()throws Exception{ObjectMapper objectMapper = new ObjectMapper();AddressList addressList = new AddressList();List<Street> streetList = new ArrayList<Street>();Street street = new Street();street.setAddressLine1("street1");street.setAddressLine2("street2");streetList.add(street);addressList.setStreetLine(streetList);addressList.setCity("china");String addressStr = objectMapper.writeValueAsString(addressList);AddressObject addressObject = objectMapper.readValue(addressStr, AddressObject.class);}

com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot deserialize instance of `com.ysl.test.bo.Street` out of START_ARRAY tokenat [Source: (String)"{"streetLine":[{"addressLine1":"street1","addressLine2":"street2"}],"city":"china","state":null,"postalCode":null,"county":null,"countryCode":null}"; line: 1, column: 15] (through reference chain: com.ysl.test.bo.AddressObject["streetLine"])

错误原因：待转换的json字符串里面（如AddressList里面的streetLine属性）为List类型的时候，而反序列化中提供的class文件对应的字段为Object属性

@Testpublic void test2()throws Exception{ObjectMapper objectMapper = new ObjectMapper();AddressObject addressObject = new AddressObject();Street street = new Street();street.setAddressLine1("street1");street.setAddressLine2("street2");addressObject.setStreetLine(street);addressObject.setCity("china");String addressStr = objectMapper.writeValueAsString(addressObject);AddressList addressList = objectMapper.readValue(addressStr, AddressList.class);}

 Cannot deserialize instance of `java.util.ArrayList` out of START_OBJECT tokenat [Source: (String)"{"streetLine":{"addressLine1":"street1","addressLine2":"street2"},"city":"china","state":null,"postalCode":null,"county":null,"countryCode":null}"; line: 1, column: 15] (through reference chain: com.ysl.test.bo.AddressList["streetLine"])

错误原因：待转换的json字符串里面（如AddressObject里面的streetLine属性）为Object类型的时候，而反序列化中提供的class文件对应的字段为List属性。

补充：

List与数组的序列化后的json字符串是一样的，由此他们之间可以互相反序列化。

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fasterxml-jackson发生Can not deserialize instance of的原因

背景：

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