我想使用 jackson-databind 將一個 json 反序列化為一個包含其他對象列表的對象。我正在嘗試在 json 下反序列化。我有 Class class1，它有一個List<NestedProp>. Prop2 是一個數組列表。List<NestedProp> prop2.結構類`class Class1 { String prop1; List<NestedProp> prop2; //setters getters}class NestedProp { String p1; String p2; //setters getters}```` "class1": { "prop1": "pp", "prop2": [ { "nestedProp": [ { "p1": "127", "p2": "1" }, { "p1": "128", "p2": "2" } ] } ] }While deserialisingI get the below exception:>com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot construct instance of `NestedProp` (although at least one Creator exists): no String-argument constructor/factory method to deserialize from String value ('127') at [Source: (File); line: 59, column: 7] (through reference chain: java.util.ArrayList[1]->Class1["prop2"]->java.util.ArrayList[0]) List<Class1> testData = objectMapper.readValue(test.json, Class1.class);
1 回答
蝴蝶不菲
TA貢獻1810條經驗 獲得超4個贊
您的JSON有效負載中有兩個數組。所以，你需要POJO為它創建額外的。請參閱以下示例：
import com.fasterxml.jackson.databind.ObjectMapper;
import java.io.File;
import java.util.List;
public class JsonApp {
public static void main(String[] args) throws Exception {
File jsonFile = new File("./resource/test.json").getAbsoluteFile();
ObjectMapper mapper = new ObjectMapper();
Root root = mapper.readValue(jsonFile, Root.class);
System.out.println(root);
}
}
class Root {
private Class1 class1;
//getters, setters, toString
}
class Class1 {
private String prop1;
private List<NestedProps> prop2;
//getters, setters, toString
}
class NestedProps {
private List<NestedProp> nestedProp;
//getters, setters, toString
}
class NestedProp {
private String p1;
private String p2;
//getters, setters, toString
}
對于以下JSON：
{
"class1": {
"prop1": "pp",
"prop2": [
{
"nestedProp": [
{
"p1": "127",
"p2": "1"
},
{
"p1": "128",
"p2": "2"
}
]
}
]
}
}
以上示例打?。?/p>
Root{class1=Class1{prop1='pp', prop2=[NestedProps{nestedProp=[NestedProp{p1='127', p2='1'}, NestedProp{p1='128', p2='2'}]}]}}
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