Question

我想使用fasterxml.jackson从json下面提取“msg”值 - 有人可以建议我的模型类应该是什么样的吗？

{
    "statusCode": 422,
    "error": "Unprocessable Entity",
    "message": "Bad data received",
    "err_data": {
        "payment_details.type": {
            "location": "body",
            "param": "payment_details.type",
            "msg": "Must be either etransfer or cheque"
        }
    }
}

这就是我所做的，但它总是返回“null”！

@JsonInclude(JsonInclude.Include.ALWAYS)
public class MyApiResponse extends ParentResponse implements Serializable {
    private static final long serialVersionUID = 1L;

    @JsonProperty("payment_details")
    private PaymentDetails payment_details;

    @JsonProperty("payment_details")
    public PaymentDetails getPayment_details() {
        return payment_details;
    }

    @JsonProperty("payment_details")
    public void setPayment_details(PaymentDetails payment_details) {
        this.payment_details = payment_details;
    }
}

ParentResponse模型类扩展了ErrorResponse模型类，这就是它的样子......

此ErrorResponse模型代表上面提到的JSON。

@JsonInclude(JsonInclude.Include.NON_NULL)
public class ErrorResponse implements Serializable {

    private static final long serialVersionUID = 1L;

    @JsonProperty("statusCode")
    private int statusCode;

    @JsonProperty("error")
    private String error;

    @JsonProperty("message")
    private String message;

    @JsonProperty("err_data")
    private ErrData err_data;

    @JsonProperty("statusCode")
    public int getStatusCode() {
        return statusCode;
    }

    @JsonProperty("statusCode")
    public void setStatusCode(int statusCode) {
        this.statusCode = statusCode;
    }

    @JsonProperty("message")
    public String getMessage() {
        return message;
    }

    @JsonProperty("message")
    public void setMessage(String message) {
        this.message = message;
    }

    @JsonProperty("error")
    public String getError() {
        return error;
    }

    @JsonProperty("error")
    public void setError(String error) {
        this.error = error;
    }

    @JsonProperty("err_data")
    public ErrData getErr_data() {
        return err_data;
    }

    @JsonProperty("err_data")
    public void setErr_data(ErrData err_data) {
        this.err_data = err_data;
    }
}

err_data对象由以下模型类表示。

@JsonInclude(JsonInclude.Include.ALWAYS)
public class ErrData implements Serializable {

    private static final long serialVersionUID = 1L;

    @JsonProperty("email")
    private Email email;

    @JsonProperty("payment_details.type")
    private PaymentDetailsType payment_details_type;

    @JsonProperty("email")
    public Email getEmail() {
        return email;
    }

    @JsonProperty("email")
    public void setEmail(Email email) {
        this.email = email;
    }

    @JsonProperty("payment_details.type")
    public PaymentDetailsType getPayment_details_type() {
        return payment_details_type;
    }

    @JsonProperty("payment_details.type")
    public void setPayment_details_type(PaymentDetailsType payment_details_type) {
        this.payment_details_type = payment_details_type;
    }
}

由下面的类代表的

payment_details.type对象。

@JsonInclude(JsonInclude.Include.ALWAYS)
public class PaymentDetailsType extends ErrorMessage implements Serializable {

    private static final long serialVersionUID = 1L;

}

@JsonInclude(JsonInclude.Include.ALWAYS)
public class Email extends ErrorMessage implements Serializable {

    private static final long serialVersionUID = 1L;

}

最后ErrorMessage由PaymentDetailsType扩展如下。

@JsonPropertyOrder({"location", "param", "value", "msg"})
public class ErrorMessage implements Serializable {

    private static final long serialVersionUID = 1L;

    @JsonProperty("location")
    private String location;

    @JsonProperty("param")
    private String param;

    @JsonProperty("value")
    private String value;

    @JsonProperty("msg")
    private String msg;

    @JsonProperty("location")
    public String getLocation() {
        return location;
    }

    @JsonProperty("location")
    public void setLocation(String location) {
        this.location = location;
    }

    @JsonProperty("param")
    public String getParam() {
        return param;
    }

    @JsonProperty("param")
    public void setParam(String param) {
        this.param = param;
    }

    @JsonProperty("value")
    public String getValue() {
        return value;
    }

    @JsonProperty("value")
    public void setValue(String value) {
        this.value = value;
    }

    @JsonProperty("msg")
    public String getMsg() {
        return msg;
    }

    @JsonProperty("msg")
    public void setMsg(String msg) {
        this.msg = msg;
    }
}

最后我试图获得“msg”字段值如下 -

new Gson().fromJson(response.asString(), MyApiResponse.class).getErr_data().getPayment_details_type().getMsg();

我认为这个有问题 - 如果json中的字段名称不确定如何定义getter方法。（点）。

@JsonProperty("payment_details.type")
public PaymentDetailsType getPayment_details_type() {
    return payment_details_type;
}

与上面类似，我在json下方执行此操作以检索“msg”值并且工作正常。

{
    "statusCode": 422,
    "error": "Unprocessable Entity",
    "message": "Bad data received",
    "err_data": {
        "email": {
            "location": "body",
            "param": "email",
            "value": "test @ com",
            "msg": "Must be a valid email"
        }
    }
}

这将返回正确的“msg”值。

new Gson().fromJson(response.asString(), MyApiResponse.class).getErr_data().getEmail().getMsg();

请建议！

谢谢。

Answer 1

这是一个最小的示例，展示了如何使用Jackson解析JSON，其中属性名称可能包含点：

import com.fasterxml.jackson.annotation.JsonProperty;
import com.fasterxml.jackson.databind.ObjectMapper;
import java.io.IOException;

class Main {
    public static void main(String[] args) throws IOException {
        String json = "{" +
                      "    \"payment_details.type\": {" +
                      "        \"location\": \"body\"" +
                      "    }" +
                      "}";
        ObjectMapper mapper = new ObjectMapper();
        Response response = mapper.readValue(json, Response.class);
        System.out.println(response.getPaymentDetailsType().getLocation());
    }
}

class Response {
    @JsonProperty("payment_details.type")
    private PaymentDetailsType paymentDetailsType;

    public PaymentDetailsType getPaymentDetailsType() { return paymentDetailsType; }
}

class PaymentDetailsType {
    private String location;

    public String getLocation() { return location; }
}

请注意，当无法从setter或变量名推导出JSON中的预期属性名时，只需要@JsonProperty

如何在对象名称中包含DOT时从json对象检索字段值

1 个答案: