把一个Hibernate对象列表放到一个JSON对象中

Question

我想将一个Hibernate对象列表添加到一个JSON对象中，但我得到StackOverflowError。

我也试过@JsonBackReference("mamRequestHeaders.mamRequestLinesSet")在MAMRequestLine.java和@JsonManagedReference("mamRequestHeaders.mamRequestLinesSet")在MAMRequestHeader.java但是问题没有解决。

java.lang.StackOverflowError的在 java.lang.reflect.InvocationTargetException。（InvocationTargetException.java:72） 在sun.reflect.GeneratedMethodAccessor494.invoke（未知来源）在 sun.reflect.DelegatingMethodAccessorImpl.invoke （DelegatingMethodAccessorImpl.java:43） at org.json.JSONObject.populateMap（JSONObject.java:988）at org.json.JSONObject。（（java.lang.reflect.Method.invoke（Method.java:498）at JSONObject.java:272） org.json.JSONObject.wrap（JSONObject.java:1587）at org.json.JSONArray。（JSONArray.java:158）at org.json.JSONO bject.wrap（JSONObject.java:1569）at org.json.JSONObject.populateMap（JSONObject.java:990）at org.json.JSONObject。（JSONObject.java:272）at org.json.JSONObject.wrap （JSONObject.java:1587）在 org.json.JSONObject.populateMap（JSONObject.java:990）

MAMRequestHeaders类

@Entity(name="MAMRequestHeaders") 
@Table(name = "MAM_REQUEST_HEADERS", uniqueConstraints = @UniqueConstraint(columnNames = {"REQUEST_TYPE", "NUM_REQUEST_MREQH"})) 
public class MAMRequestHeaders implements Serializable { 

    private long id ; 
    private Set<MAMRequestLines> mamRequestLinesSet; 

    @Id 
    @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "MAM_REQUEST_HEADERS_SEQ") 
    @SequenceGenerator(name = "MAM_REQUEST_HEADERS_SEQ", sequenceName = "MAM_REQUEST_HEADERS_SEQ") 
    @Column(name = "REQUEST_HEADER_ID") 
    public long getId() { 
     return id; 
    } 

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

    @OneToMany(mappedBy = "mamRequestHeaders", fetch = FetchType.EAGER, cascade = CascadeType.ALL, orphanRemoval = true) 
    @OnDelete(action = OnDeleteAction.CASCADE) 
    public Set<MAMRequestLines> getMamRequestLinesSet() { 
     return mamRequestLinesSet; 
    } 

    public void setMamRequestLinesSet(Set<MAMRequestLines> mamRequestLinesSet) { 
     this.mamRequestLinesSet = mamRequestLinesSet; 
    } 

} 

MAMRequestLines类

@Entity(name = "MAMRequestLines") 
@Table(name = "MAM_REQUEST_LINES", uniqueConstraints = @UniqueConstraint(columnNames = {"REQUEST_HEADER_ID", "NUM_LINE_MREQL"})) 
public class MAMRequestLines implements Serializable { 

    private Long id; 
    @JsonIgnore 
    private MAMRequestHeaders mamRequestHeaders; 

    @Id 
    @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "MAM_REQUEST_Line_SEQ") 
    @SequenceGenerator(name = "MAM_REQUEST_Line_SEQ", sequenceName = "MAM_REQUEST_Line_SEQ") 
    @Column(name = "REQUEST_LINE_ID") 
    public Long getId() { 
     return id; 
    } 

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

    @ManyToOne(fetch = FetchType.EAGER) 
    @JoinColumn(name = "REQUEST_HEADER_ID", nullable = false) 
    public MAMRequestHeaders getMamRequestHeaders() { 
     return mamRequestHeaders; 
    } 

    public void setMamRequestHeaders(MAMRequestHeaders mamRequestHeaders) { 
     this.mamRequestHeaders = mamRequestHeaders; 
    } 

} 

创建结果

List<MAMRequestHeaders> mamRequestHeadersList = manager.createQuery(queryStr, MAMRequestHeaders.class) 
JSONObject result = new JSONObject(); 
result.put("resultList", mamRequestHeadersList); 

Answer 1

您@ManyToOne场添加@JsonManagedReference您@OneToMany收集和@JsonBackReference。请参阅下面的更新示例。

MAMRequestHeaders类

@Entity(name="MAMRequestHeaders") 
@Table(name = "MAM_REQUEST_HEADERS", uniqueConstraints = @UniqueConstraint(columnNames = {"REQUEST_TYPE", "NUM_REQUEST_MREQH"})) 
public class MAMRequestHeaders implements Serializable { 

    private long id; 

    @JsonBackReference 
    private Set<MAMRequestLines> mamRequestLinesSet; 

    @Id 
    @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "MAM_REQUEST_HEADERS_SEQ") 
    @SequenceGenerator(name = "MAM_REQUEST_HEADERS_SEQ", sequenceName = "MAM_REQUEST_HEADERS_SEQ") 
    @Column(name = "REQUEST_HEADER_ID") 
    public long getId() { 
     return id; 
    } 

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

    @OneToMany(mappedBy = "mamRequestHeaders", fetch = FetchType.EAGER, cascade = CascadeType.ALL, orphanRemoval = true) 
    @OnDelete(action = OnDeleteAction.CASCADE) 
    public Set<MAMRequestLines> getMamRequestLinesSet() { 
     return mamRequestLinesSet; 
    } 

    public void setMamRequestLinesSet(Set<MAMRequestLines> mamRequestLinesSet) { 
     this.mamRequestLinesSet = mamRequestLinesSet; 
    } 

} 

MAMRequestLines类

@Entity(name = "MAMRequestLines") 
@Table(name = "MAM_REQUEST_LINES", uniqueConstraints = @UniqueConstraint(columnNames = {"REQUEST_HEADER_ID", "NUM_LINE_MREQL"})) 
public class MAMRequestLines implements Serializable { 

    private Long id; 

    @JsonManagedReference 
    private MAMRequestHeaders mamRequestHeaders; 

    @Id 
    @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "MAM_REQUEST_Line_SEQ") 
    @SequenceGenerator(name = "MAM_REQUEST_Line_SEQ", sequenceName = "MAM_REQUEST_Line_SEQ") 
    @Column(name = "REQUEST_LINE_ID") 
    public Long getId() { 
     return id; 
    } 

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

    @ManyToOne(fetch = FetchType.EAGER) 
    @JoinColumn(name = "REQUEST_HEADER_ID", nullable = false) 
    public MAMRequestHeaders getMamRequestHeaders() { 
     return mamRequestHeaders; 
    } 

    public void setMamRequestHeaders(MAMRequestHeaders mamRequestHeaders) { 
     this.mamRequestHeaders = mamRequestHeaders; 
    } 

} 

但实际上配置JSON注解取决于你所需的输出。例如，您也可以在MAMRequestLines类中的getMamRequestHeaders()上放置@JsonIgnore。