使用 gson 反序列化 Java 数组/列表

Question

我在 Java 中使用 gson 来反序列化来自 Azure EventGrid 的一些 JSON（它基本上只是常规的 JSON 消息）。我不断收到malmformed JSON 引发的异常，或者只是像unterminated object at line 1 column 13 path $[0].msg 这样的奇怪错误

这就是我试图反序列化的 JSON 的样子：

{
  "id": "3984520-582350923-52389532042802",
  "subject": "/v1-1/URL_PATH_HERE",
  "data": [
    {
    "msg": "randomMsgHere",
    "time": 1599922804852,
    "type": "",
    "alarm": true,
    "source": "",
    "category": "",
    "severity": "",
    "elementId": "",
    "networkId": "",
    "hardwareType": "",
    "failureObject": "",
    "reportingAgent": "",
    "sourceDisplayName": "",
    "failureObjectDisplayName": "",
    "managedObjectDisplayName": "",
    "extendedAttributes": {
        "eventId": 100,
        "customerAlias": "string",
        "latitude": 10.00,
        "longitude": 10.00,
        "elevation": 10.00
    }
}
  ],
  "eventType": "eventType",
  "dataVersion": "1",
  "metadataVersion": "1",
  "eventTime": "2020-10-13T01:41:32.765Z",
  "topic": "randomTopicHere"
}

我只是在其中放了一些随机数据（假设空字符串有数据），我正在调用一个方法来提取或获取（） JSON 的 data [ ] 属性，所以我应该得到一个数组。我已经在 J​​ava 中定义了一个数据类，所以我可以轻松地对其进行反序列化，但我通常使用来自 Jackson 的 Kotlin 数据类和对象映射器，我认为这个数组存在问题。

将此 JSON 字符串转换为像这样定义的 EventState.class 的最简单方法是什么？

@Getter
    @Setter
public class EventState {
    private String msg;
    private long time;
    private String type;
    private boolean alarm;
    private String source;
    private String category;
    private String severity;
    private String elementId;
    private String networkId;
    private String hardwareType;
    private String failureObject;
    private String reportingAgent;
    private String sourceDisplayName;
    private String failureObjectDisplayName;
    private String managedObjectDisplayName;
    private ExtendedAttributes extendedAttributes;

    @Getter
    @Setter
    public static class ExtendedAttributes {
        private int eventId;
        private String customerAlias;
        private Double latitude;
        private Double longitude;
        private Double elevation;
    }

Answer 1

上面的 json 字符串很容易通过 gson 解析，只需在 Eventstate 周围添加一个容器。

这是一个例子：

public class Test {

public static void main(String[] args) {
    String value = "{\n" +
            "  \"id\": \"3984520-582350923-52389532042802\",\n" +
            "  \"subject\": \"/v1-1/URL_PATH_HERE\",\n" +
            "  \"data\": [\n" +
            "    {\n" +
            "    \"msg\": \"randomMsgHere\",\n" +
            "    \"time\": 1599922804852,\n" +
            "    \"type\": \"\",\n" +
            "    \"alarm\": true,\n" +
            "    \"source\": \"\",\n" +
            "    \"category\": \"\",\n" +
            "    \"severity\": \"\",\n" +
            "    \"elementId\": \"\",\n" +
            "    \"networkId\": \"\",\n" +
            "    \"hardwareType\": \"\",\n" +
            "    \"failureObject\": \"\",\n" +
            "    \"reportingAgent\": \"\",\n" +
            "    \"sourceDisplayName\": \"\",\n" +
            "    \"failureObjectDisplayName\": \"\",\n" +
            "    \"managedObjectDisplayName\": \"\",\n" +
            "    \"extendedAttributes\": {\n" +
            "        \"eventId\": 100,\n" +
            "        \"customerAlias\": \"string\",\n" +
            "        \"latitude\": 10.00,\n" +
            "        \"longitude\": 10.00,\n" +
            "        \"elevation\": 10.00\n" +
            "    }\n" +
            "}\n" +
            "  ],\n" +
            "  \"eventType\": \"eventType\",\n" +
            "  \"dataVersion\": \"1\",\n" +
            "  \"metadataVersion\": \"1\",\n" +
            "  \"eventTime\": \"2020-10-13T01:41:32.765Z\",\n" +
            "  \"topic\": \"randomTopicHere\"\n" +
            "}";
    Gson gson = new Gson();
    EventStateContainer eventStateContainer = gson.fromJson(value, EventStateContainer.class);
    System.out.println(eventStateContainer.getData());
}

public class EventStateContainer {
    private String id;
    private String subject;
    private ArrayList<EventState> data;

    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

    public String getSubject() {
        return subject;
    }

    public void setSubject(String subject) {
        this.subject = subject;
    }

    public ArrayList<EventState> getData() {
        return data;
    }

    public void setData(ArrayList<EventState> data) {
        this.data = data;
    }
}

public class EventState {
    private String msg;
    private long time;
    private String type;
    private boolean alarm;
    private String source;
    private String category;
    private String severity;
    private String elementId;
    private String networkId;
    private String hardwareType;
    private String failureObject;
    private String reportingAgent;
    private String sourceDisplayName;
    private String failureObjectDisplayName;
    private String managedObjectDisplayName;
    private ExtendedAttributes extendedAttributes;

    public String getMsg() {
        return msg;
    }

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

    public long getTime() {
        return time;
    }

    public void setTime(long time) {
        this.time = time;
    }

    public String getType() {
        return type;
    }

    public void setType(String type) {
        this.type = type;
    }

    public boolean isAlarm() {
        return alarm;
    }

    public void setAlarm(boolean alarm) {
        this.alarm = alarm;
    }

    public String getSource() {
        return source;
    }

    public void setSource(String source) {
        this.source = source;
    }

    public String getCategory() {
        return category;
    }

    public void setCategory(String category) {
        this.category = category;
    }

    public String getSeverity() {
        return severity;
    }

    public void setSeverity(String severity) {
        this.severity = severity;
    }

    public String getElementId() {
        return elementId;
    }

    public void setElementId(String elementId) {
        this.elementId = elementId;
    }

    public String getNetworkId() {
        return networkId;
    }

    public void setNetworkId(String networkId) {
        this.networkId = networkId;
    }

    public String getHardwareType() {
        return hardwareType;
    }

    public void setHardwareType(String hardwareType) {
        this.hardwareType = hardwareType;
    }

    public String getFailureObject() {
        return failureObject;
    }

    public void setFailureObject(String failureObject) {
        this.failureObject = failureObject;
    }

    public String getReportingAgent() {
        return reportingAgent;
    }

    public void setReportingAgent(String reportingAgent) {
        this.reportingAgent = reportingAgent;
    }

    public String getSourceDisplayName() {
        return sourceDisplayName;
    }

    public void setSourceDisplayName(String sourceDisplayName) {
        this.sourceDisplayName = sourceDisplayName;
    }

    public String getFailureObjectDisplayName() {
        return failureObjectDisplayName;
    }

    public void setFailureObjectDisplayName(String failureObjectDisplayName) {
        this.failureObjectDisplayName = failureObjectDisplayName;
    }

    public String getManagedObjectDisplayName() {
        return managedObjectDisplayName;
    }

    public void setManagedObjectDisplayName(String managedObjectDisplayName) {
        this.managedObjectDisplayName = managedObjectDisplayName;
    }

    public ExtendedAttributes getExtendedAttributes() {
        return extendedAttributes;
    }

    public void setExtendedAttributes(ExtendedAttributes extendedAttributes) {
        this.extendedAttributes = extendedAttributes;
    }

    @Override
    public String toString() {
        return "EventState{" +
                "msg='" + msg + '\'' +
                ", time=" + time +
                ", type='" + type + '\'' +
                ", alarm=" + alarm +
                ", source='" + source + '\'' +
                ", category='" + category + '\'' +
                ", severity='" + severity + '\'' +
                ", elementId='" + elementId + '\'' +
                ", networkId='" + networkId + '\'' +
                ", hardwareType='" + hardwareType + '\'' +
                ", failureObject='" + failureObject + '\'' +
                ", reportingAgent='" + reportingAgent + '\'' +
                ", sourceDisplayName='" + sourceDisplayName + '\'' +
                ", failureObjectDisplayName='" + failureObjectDisplayName + '\'' +
                ", managedObjectDisplayName='" + managedObjectDisplayName + '\'' +
                ", extendedAttributes=" + extendedAttributes +
                '}';
    }
}

public static class ExtendedAttributes {
    private int eventId;
    private String customerAlias;
    private Double latitude;
    private Double longitude;
    private Double elevation;

    public int getEventId() {
        return eventId;
    }

    public void setEventId(int eventId) {
        this.eventId = eventId;
    }

    public String getCustomerAlias() {
        return customerAlias;
    }

    public void setCustomerAlias(String customerAlias) {
        this.customerAlias = customerAlias;
    }

    public Double getLatitude() {
        return latitude;
    }

    public void setLatitude(Double latitude) {
        this.latitude = latitude;
    }

    public Double getLongitude() {
        return longitude;
    }

    public void setLongitude(Double longitude) {
        this.longitude = longitude;
    }

    public Double getElevation() {
        return elevation;
    }

    public void setElevation(Double elevation) {
        this.elevation = elevation;
    }

    @Override
    public String toString() {
        return "ExtendedAttributes{" +
                "eventId=" + eventId +
                ", customerAlias='" + customerAlias + '\'' +
                ", latitude=" + latitude +
                ", longitude=" + longitude +
                ", elevation=" + elevation +
                '}';
    }
}

}

最好的问候

托本