无法使用杰克逊将具有内部对象的 JSON 解析为 Java 对象

Question

我正在使用 Spring 开发项目并希望将字符串格式的 JSON 数据解析到控制器。为了说明问题，我写了下面的小程序。

没有足够的护目镜，但没有运气。希望能在本站得到解答。 问题：无法解析内部对象，即 A3PatientRecordStatusBean。 程序输出：MedicPatientRecordDataStatusBean [a3PatientRecordStatusBean=null]

尝试执行 JSON 解析的主程序：

public static void main(String[] args) {
        String jsonString = "{\"a3PatientRecordStatusBean\":{\"patientRecordId\":\"1\",\"messageCode\":\"2000\"}}";
        ObjectMapper mapper = new ObjectMapper();
        try {
            MedicPatientRecordDataStatusBean medicPatientRecordDataStatusBean = mapper.readValue(jsonString, MedicPatientRecordDataStatusBean.class);
            System.out.println(medicPatientRecordDataStatusBean);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

外部类/对象：

@JsonAutoDetect
public class MedicPatientRecordDataStatusBean implements Serializable {
    private static final long serialVersionUID = -4917476398283528449L;

    private A3PatientRecordStatusBean a3PatientRecordStatusBean;

    /**
     * @return the a3PatientRecordStatusBean
     */
    public A3PatientRecordStatusBean getA3PatientRecordStatusBean() {
        return a3PatientRecordStatusBean;
    }

    /**
     * @param a3PatientRecordStatusBean
     *            the a3PatientRecordStatusBean to set
     */
    public void setA3PatientRecordStatusBean(
            A3PatientRecordStatusBean a3PatientRecordStatusBean) {
        a3PatientRecordStatusBean = a3PatientRecordStatusBean;
    }

    /*
     * (non-Javadoc)
     * 
     * @see java.lang.Object#toString()
     */
    @Override
    public String toString() {
        return "MedicPatientRecordDataStatusBean [a3PatientRecordStatusBean="
                + a3PatientRecordStatusBean + "]";
    }

}

内部对象类：

@JsonAutoDetect
public class A3PatientRecordStatusBean implements Serializable {
    private static final long serialVersionUID = -4585669896170562832L;
    private String patientRecordId = "";
    private String messageCode = "";

    /**
     * @return the patientRecordId
     */
    public String getPatientRecordId() {
        return patientRecordId;
    }

    /**
     * @param patientRecordId
     *            the patientRecordId to set
     */
    public void setPatientRecordId(String patientRecordId) {
        this.patientRecordId = patientRecordId;
    }

    /**
     * @return the messageCode
     */
    public String getMessageCode() {
        return messageCode;
    }

    /**
     * @param messageCode
     *            the messageCode to set
     */
    public void setMessageCode(String messageCode) {
        this.messageCode = messageCode;
    }

    @Override
    public String toString() {
        return "A3PatientRecordStatusBean [patientRecordId=" + patientRecordId
                + ", messageCode=" + messageCode + "]";
    }

}

Answer 1

花了很多小时后，我能够解析 JSON 字符串并使用 Jackson 加载 Java 对象。以下是修改后的工作代码。 总之，我做了以下。

1. 从 bean 类中删除了 @JsonAutoDetect、Serializable、serialVersionUID 等。
2. 创建了只有实例变量和 set/get 方法的简单 bean。
3. 开发了重写的 toString() 方法。

以下是没有任何错误的类。类中的一些实例变量可能略有不同，但应该能够传达信息。

MedicPatientRecordDataStatusBean 类

public class MedicPatientRecordDataStatusBean {
private int messageCode;
private A3PatientRecordStatusBean a3PatientRecordStatusBean;

public int getMessageCode() {
    return messageCode;
}
public void setMessageCode(int messageCode) {
    this.messageCode = messageCode;
}
public A3PatientRecordStatusBean getA3PatientRecordStatusBean() {
    return a3PatientRecordStatusBean;
}
public void setA3PatientRecordStatusBean(
        A3PatientRecordStatusBean a3PatientRecordStatusBean) {
    this.a3PatientRecordStatusBean = a3PatientRecordStatusBean;
}
@Override
public String toString() {
    return "MedicPatientRecordDataStatusBean [messageCode=" + messageCode
            + ", a3PatientRecordStatusBean=" + a3PatientRecordStatusBean"]";
}

}

A3PatientRecordStatusBean

public class A3PatientRecordStatusBean {
private int patientRecordId;
private int patientProfile;
private int messageCode;

public int getPatientRecordId() {
    return patientRecordId;
}
public void setPatientRecordId(int patientRecordId) {
    this.patientRecordId = patientRecordId;
}
public int getPatientProfile() {
    return patientProfile;
}
public void setPatientProfile(int patientProfile) {
    this.patientProfile = patientProfile;
}
public int getMessageCode() {
    return messageCode;
}
public void setMessageCode(int messageCode) {
    this.messageCode = messageCode;
}

@Override
public String toString() {
    return "A3PatientRecordStatusBean [patientRecordId=" + patientRecordId
            + ", patientProfile=" + patientProfile + ", messageCode="
            + messageCode + "]";
}

}

希望这将有助于其他开发人员，并且不会花时间在 JSON 字符串解析上。 最后感谢堆栈溢出以及所有的帮助和建议。

Answer 2

我认为在这种情况下您需要注释 MedicPatientRecordDataStatusBean 'private A3PatientRecordStatusBean a3PatientRecordStatusBean;' 中的字段用@JsonUnwrapped