Question

我在我的Spring项目中使用hibernate在java类中映射我的表并使用FetchType.LAZY我添加了@JsonIgnore以避免在json映射期间发生异常。使用此配置，性能良好。这是一个例子：

@Entity
@Table(name = "clientversion", catalog = "ats")
public class ClientVersion implements java.io.Serializable {

    /**
     * 
     */
    private static final long serialVersionUID = 1L;
    private Integer idClientVersion;
    private String name;
    private Date releaseDate;
    private String note;
    private String filePath;

    @JsonIgnore
    private Set<User> users = new HashSet<User>(0);

    public ClientVersion() {
    }

    /**
     * @param idClientVersion
     * @param name
     * @param releaseDate
     * @param users
     */
    public ClientVersion(Integer idClientVersion, String name, Date releaseDate, String note, String filePath, Set<User> users) {
        this.idClientVersion = idClientVersion;
        this.name = name;
        this.note = note;
        this.releaseDate = releaseDate;
        this.users = users;
        this.setFilePath(filePath);
    }



    @Id
    @GeneratedValue(strategy = IDENTITY)
    @Column(name = "id_clientVersion", unique = true, nullable = false)
    public Integer getIdClientVersion() {
        return this.idClientVersion;
    }

    public void setIdClientVersion(Integer idClientVersion) {
        this.idClientVersion = idClientVersion;
    }



    /**
     * @return the name
     */
    @Column(name = "name", nullable = false)
    public String getName() {
        return name;
    }

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

    /**
     * @return the releaseDate
     */
    @Column(name = "releaseDate", nullable = false)
    public Date getReleaseDate() {
        return releaseDate;
    }

    /**
     * @param releaseDate the releaseDate to set
     */
    public void setReleaseDate(Date releaseDate) {
        this.releaseDate = releaseDate;
    }

    /**
     * @return the note
     */
    @Column(name = "note")
    public String getNote() {
        return note;
    }

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

    @OneToMany(fetch = FetchType.LAZY, mappedBy = "clientVersion")
    public Set<User> getUsers() {
        return this.users;
    }

    public void setUsers(Set<User> users) {
        this.users = users;
    }

    /**
     * @return the filePath
     */
    @Column(name = "filePath")
    public String getFilePath() {
        return filePath;
    }

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

这里我没有任何注释，但我无法获得用户：

@Entity
@Table(name = "clientlicense", catalog = "ats")
public class ClientLicense implements java.io.Serializable{

    private static final long serialVersionUID = 1L;
    private Integer idClientLicense;
    private Date startDate;
    private Date endDate;
    private int counter;
    private String macAddress;
    private String cpuId;
    private User user;

    public ClientLicense() {
    }

    public ClientLicense(Date startDate, Date endDate, int counter, String macAddress, String cpuId, User user) {
        super();
        this.startDate = startDate;
        this.endDate = endDate;
        this.counter = counter;
        this.setMacAddress(macAddress);
        this.setCpuId(cpuId);
        this.user = user;
    }

    @Id
    @GeneratedValue(strategy = IDENTITY)
    @Column(name = "id_clientLicense", unique = true, nullable = false)
    public Integer getIdClientLicense() {
        return this.idClientLicense;
    }

    public void setIdClientLicense(Integer idClientLicense) {
        this.idClientLicense = idClientLicense;
    }


    @Column(name = "startDate", nullable = false)
    @Temporal(TemporalType.DATE)//This annotation allows to use only YYYY/MM/DD
    public Date getStartDate() {
        return this.startDate;
    }

    public void setStartDate(Date startDate) {
        this.startDate = startDate;
    }

    @Column(name = "endDate", nullable = false)
    @Temporal(TemporalType.DATE)
    public Date getEndDate() {
        return this.endDate;
    }

    public void setEndDate(Date endDate) {
        this.endDate = endDate;
    }


    @Column(name = "counter", nullable = false)
    public int getCounter() {
        return this.counter;
    }

    public void setCounter(int counter) {
        this.counter = counter;
    }   

    @Column(name = "macAddress", nullable = false)
    public String getMacAddress() {
        return macAddress;
    }

    public void setMacAddress(String macAddress) {
        this.macAddress = macAddress;
    }

    @Column(name = "cpuId", nullable = false)
    public String getCpuId() {
        return cpuId;
    }

    public void setCpuId(String cpuId) {
        this.cpuId = cpuId;
    }

    @OneToOne(fetch = FetchType.LAZY, cascade = CascadeType.MERGE)
    @JoinColumn(name = "id_username")
    public User getUser() {
        return this.user;
    }

    public void setUser(User user) {
        this.user = user;
    }
}

这是返回的json：

{"data":[{"idClientLicense":30,"startDate":"2016-02-10","endDate":"2016-02-19","counter":350,"macAddress":"1223","cpuId":"123CPU","user":null}]}

有时我需要在我的界面中使用user.username字段，但使用此代码我不会收到用户，因为我使用了@JsonIgnore。为了解决这个问题，我使用新的列表复制了返回的List，我在其中设置了字段，但这是一个不好的做法，因为我可能会复制许多元素。解决此问题的最佳做法是什么？

Answer 1

最近有同样的问题。我认为杰克逊JsonView可能是一个可行的解决方案。

请参阅here和there

在hibernate实体中使用@JsonIgnore和FetchType.LAZY

1 个答案: