ObjectMapper 在映射到 JSON 时忽略某些字段

Question

所以我的问题是，当将 class 映射到 JSON 时，它不会映射 class 具有

的所有字段

卡片:

public class Card {
    private String name;
    private String description;
    private StatusCard status;
    private List<String> CardHistory;
    public enum StatusCard{TODO, INPROGRESS, TOBEREVISED, DONE};

    public Card(String name, String desc){
        this.name = name;
        description = desc;
        status = StatusCard.TODO;
        CardHistory = new ArrayList<>();
    }

    public Card(){}

    // getters and setters
}

这个 class 在另一个 class 中使用，在一个 ArrayList<Card> cardList，但是当我将此 class 映射到 JSON 时，这是它唯一映射的字段

JSON:

... "cardList":[{"name":"test","status":"TODO"}] ...

我不明白为什么。这是服务器添加新卡的方法：

public String addCard(String projectName, String cardName, String desc, String nickUtente) {
    if (projects.isEmpty())
        return "No projects are currently present";
    if (projectName.isEmpty() || cardName.isEmpty() || desc.isEmpty() || nickUtente.isEmpty())
        return "Missing one or more arguments";

    for (Project p : projects) {
        if (p.getName().equalsIgnoreCase(projectName)){
            if (!p.isMember(nickUtente))
                return nickUtente + " does not belong to the project";
            String code = p.addCard(cardName, desc);
            if (code.equalsIgnoreCase("ok")) {
                try {
                    om.writeValue(projectFile,projects);
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            return code;
        }
    }
    return "Project " + projectName + " not found";
}

这是 Project class 使用 com.fasterxml.jackson 中的 classes 如果你需要知道：

public class Project implements Serializable {

    private String name;
    private String nickUtente;
    private ArrayList<Card> cardList;
    private ArrayList<String> users;
    private ArrayList<String> TODO;
    private ArrayList<String> INPROGRESS;
    private ArrayList<String> TOBEREVISED;
    private ArrayList<String> DONE;
    private String MulticastAddress;
    private int port;

    /*
    @JsonIgnore
    private File projDir;
    @JsonIgnore
    private final ObjectMapper map;
    */

    public Project(String name, String nickUtente, String multiaddr, int port) {
        this.name = name;
        this.nickUtente = nickUtente;
        cardList = new ArrayList<>();
        users = new ArrayList<>();
        users.add(nickUtente);
        TODO = new ArrayList<>();
        INPROGRESS = new ArrayList<>();
        TOBEREVISED = new ArrayList<>();
        DONE = new ArrayList<>();
        MulticastAddress = multiaddr;
        this.port = port;
        // map = new ObjectMapper();
        // map.enable(SerializationFeature.INDENT_OUTPUT);
        // projDir = new File("./BackupCards/" + name);
        // if(!projDir.exists()) projDir.mkdir();
    }

    public Project(){
        // this.map = new ObjectMapper();
        // map.enable(SerializationFeature.INDENT_OUTPUT);
    }
    
    // getters and setters

    public boolean isMember(String user){
        if(users.isEmpty())
            return false;
        for(String s : users) {
            if (user.equals(s))
                return true;
        }
        return false;
    }

    public String addMember(String s) {
        if (s.isEmpty()){
            System.out.println("Missing name");
            return "err";
        }
        if (users.contains(s)) {
            System.out.println("Member exists already");
            return "err";
        }
        users.add(s);
        return "ok";
    }

    public String addCard(String cardName, String desc){
        if(cardName.isEmpty() || desc.isEmpty())
            return "Missing name and/or description";
        Card c = new Card(cardName, desc);
        cardList.add(c);
        TODO.add(cardName);
        /* 
        File cardFile = new File(projDir + "/" + cardName + ".json");
        if (!cardFile.exists()) {
            try {
                cardFile.createNewFile();
            } catch (IOException e) { e.printStackTrace(); }
        }
        //Backup card file
        try {
            map.writeValue(cardFile, c);
        } catch (IOException e) {
            e.printStackTrace();
        }*/
        return "ok";
    }

    public String moveCard(String cardName, String startingList, String destList){
        if(cardName.isEmpty() || startingList.isEmpty() || destList.isEmpty())
            return "Missing one or more arguments";
        for(Card c : cardList){
            if(c.getName().equalsIgnoreCase(cardName)){
                switch(destList){
                    case "TODO":
                        if(startingList.equals("TODO"))
                            return "Card is already in " + startingList;
                        return "Cannot move card back to TODO";
                    case "INPROGRESS":
                        if(startingList.equals("INPROGRESS"))
                            return "Card already is in INPROGRESS";
                        if(startingList.equals("DONE"))
                            return "Card is done. Cannot change status anymore";
                        if(TODO.contains(cardName)){
                            TODO.remove(cardName);
                            INPROGRESS.add(cardName);
                            c.setStatus("INPROGRESS");
                            c.getCardHistory().add(startingList);
                            //System.out.println("Card moved from TODO to INPROGRESS");
                            return "ok";
                        }
                        if(TOBEREVISED.contains(cardName)){
                            TOBEREVISED.remove(cardName);
                            INPROGRESS.add(cardName);
                            c.setStatus("INPROGRESS");
                            c.getCardHistory().add(startingList);
                            //System.out.println("Card moved from TOBEREVISED to INPROGRESS");
                            return "ok";
                        }
                        return "Card not found";
                    case "TOBEREVISED":
                        if(!startingList.equals("INPROGRESS"))
                            return "Can only move to TOBEREVISED from INPROGRESS";
                        if(INPROGRESS.contains(cardName)){
                            INPROGRESS.remove(cardName);
                            TOBEREVISED.add(cardName);
                            c.setStatus("TOBEREVISED");
                            c.getCardHistory().add(startingList);
                            //System.out.println("Card moved FROM INPROGRESS TO TOBEREVISED");
                            return "ok";
                        }
                    case "DONE":
                        if(startingList.equals("TODO"))
                            return "Cannot move card to DONE from TODO";
                        if(INPROGRESS.contains(cardName)){
                            INPROGRESS.remove(cardName);
                            DONE.add(cardName);
                            c.getCardHistory().add(startingList);
                            c.setStatus("DONE");
                            //System.out.println("Moved card from INPROGRESS to DONE");
                            return "ok";
                        }
                        if(TOBEREVISED.contains(cardName)){
                        TOBEREVISED.remove(cardName);
                        DONE.add(cardName);
                        c.setStatus("DONE");
                        c.getCardHistory().add(startingList);
                        //System.out.println("Moved card from TOBEREVISED to DONE");
                        return "ok";
                        }
                        return "Card not found";
                    }
                }
            }
        return "Card not found";
    }

    public void showMembers() {
        if (users.isEmpty())
            System.out.println("No user belongs to this project");
        for (String s : users)
            System.out.println(s);
    }

    public void showCards() {
        if (TODO.isEmpty() && INPROGRESS.isEmpty() && TOBEREVISED.isEmpty() && DONE.isEmpty())
            System.out.println("No cards to be shown");
        if (TODO.isEmpty()) {
            System.out.println("No cards TODO");
        } else {
            System.out.println("Cards TODO:");
            for (String s : TODO)
                System.out.println(s);
        }
        if (INPROGRESS.isEmpty()) {
            System.out.println("No cards IN PROGRESS");
        } else {
            System.out.println("Cards INPROGRESS:");
            for (String s : INPROGRESS)
                System.out.println(s);
        }
        if (TOBEREVISED.isEmpty())
            System.out.println("No cards TOBEREVISED");
        else {
            System.out.println("Cards TOBEREVISED:");
            for (String s : TOBEREVISED)
                System.out.println(s);
        }
        if (DONE.isEmpty())
            System.out.println("No cards DONE");
        else {
            System.out.println("Cards DONE:");
            for (String s : DONE)
                System.out.println(s);
        }
    }

    public Card getCard(String name) {
        if (cardList.isEmpty())
            return null;
        for (Card c : cardList){
            if (c.getName().equalsIgnoreCase(name))
                return c;
        }
        return null;
    }

    public List<UserStatusInfo> getCardList() {
        if(cardList.isEmpty())
            return null;
        List<UserStatusInfo> list = new ArrayList<>();
        for(Card c : cardList)
            list.add(new UserStatusInfo(c.getName(),c.getStatus()));
        return list;
    }

  /*  public void delProjDir(){
        try {
            Files.walk(projDir.toPath()).sorted(Comparator.reverseOrder()).map(Path::toFile)
                    .forEach(File::delete);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
*/
}

Answer 1

问题就在这里

public List<UserStatusInfo> getCardList() {
    if(cardList.isEmpty())
        return null;
    List<UserStatusInfo> list = new ArrayList<>();
    for(Card c : cardList)
        list.add(new UserStatusInfo(c.getName(),c.getStatus()));
    return list;
}

您有私有属性 ArrayList<Card> cardList 和 public 方法 List<UserStatusInfo> getCardList()。由于 ObjectMapper 在序列化期间遵循 JavaBean 约定，它仅访问 public 属性和 public getter 方法，因此当 cardList 映射到 JSON 时，而不是 cardList ] 属性实际上是序列化的，但是 getCardList() 方法调用的结果因此不是 Card 个实例被序列化而是 UserStatusInfo 个实例（似乎只有 name 和 status).

您必须创建 ArrayList<Card> getCardList() 方法 returns cardList 属性，并将当前 List<UserStatusInfo> getCardList() 重命名为其他名称

或

扩展 UserStatusInfo class 使其具有 Card

的所有对应属性

ObjectMapper 在映射到 JSON 时忽略某些字段

ObjectMapper ignores some fileds when mapping to JSON

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