Jackson POJO映射ArrayList <Class>無法識別的字段

Question

我無法將JSON響應映射到自定義類的數組列表。

問題是它無法識別JSON響應中的「userswithdistance」字段，即使我在JSONResponse類中將其設置爲ArrayList。錯誤：

com.fasterxml.jackson.databind.exc.UnrecognizedPropertyException: Unrecognized field "userswithdistance" (class com.az.d.classes.models.JSONResponse), not marked as ignorable (4 known properties: "success", "usersWithDistance", "action", "error"]) 

這裏是JSON響應

{ 
    "action": "get_users", 
    "success": 1, 
    "error": 0, 
    "userswithdistance": [ 
     { 
      "usr_id": "4", 
      "distance": 9896.348 
     }, 
     { 
      "usr_id": "5", 
      "distance": 11536.063 
     } 
    ] 
} 

這是JSONResponse類來包裝JSON響應。

public class JSONResponse { 
    private String _action; 
    private int _success; 
    private int _error; 

    private ArrayList<UsersWithDistance> _userswithdistance; 

    public String getAction() { return _action; } 
    public int getSuccess() { return _success; } 
    public int getError() { return _error; } 
    public ArrayList<UsersWithDistance> getUsersWithDistance() { return _userswithdistance; } 

    public void setAction(String value) { _action = value; } 
    public void setSuccess(int value) { _success = value; } 
    public void setError(int value) { _error = value; } 
    public void setUsersWithDistance(ArrayList<UsersWithDistance> value) { _userswithdistance = value; } 
} 

這裏是UsersWithDistance類。

public class UsersWithDistance { 
    private String _usr_id; 
    private double _distance; 

    public String getUsr_id() { return _usr_id; } 
    public double getDistance() { return _distance; } 

    public void setUsr_id(String value) { _usr_id = value; } 
    public void setDistance(double value) { _distance = value; } 
} 

我在Java中使用的代碼是：

JSONResponse result = mapper.readValue(URL, JSONResponse.class); 

Answer 1

你必須選擇：

一變化setter方法名：

public void setUserswithdistance(ArrayList<UsersWithDistance> _userswithdistance) { 
      this._userswithdistance = _userswithdistance; 
} 

II。添加JsonProperty註釋：

@JsonProperty("userswithdistance") 
    private ArrayList<UsersWithDistance> _userswithdistance;