[英]How to convert bean with reference bean to json in java?
我正在尝试通过Gson将bean转换为json。 我的bean(日志)包括另一个bean(日志)和对第一个bean的第二个bean引用。
@Entity
@Table(name = "t_logs")
public class Logs {
@Id
@Column(name = "executionid")
private String executionId;
@Column(name = "sentdate")
@Temporal(TemporalType.TIMESTAMP)
private Date sentDate;
@Column(name = "sent")
private boolean sent;
@OneToMany(mappedBy = "logs", cascade = CascadeType.ALL, fetch = FetchType.EAGER)
private List<Log> logList;}
@Entity
@Table(name = "t_log")
public class Log {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
@Column(name = "id")
private long id;
@ManyToOne
@JoinColumn(name = "executionid")
private Logs logs;
@Column(name = "startdate")
@Temporal(TemporalType.TIMESTAMP)
private Date startDate;
@Column(name = "enddate")
@Temporal(TemporalType.TIMESTAMP)
private Date endDate;
}
因此,当我尝试转换Json格式时,出现类似上面的错误; java.lang.StackOverflowError的
我认为这是一个周期,但是我如何解决它,我不知道
Gson gson = new GsonBuilder().setDateFormat("yyyy-MM-dd'T'HH:mm:ssZ").create();
return gson.toJson(logs, Logs.class);
您在日志和日志之间有循环引用。
当您尝试将日志转换为Json时,它将转换日志及其引用。 但是log引用了Logs,而Logs引用了再次记录日志并继续。 因此堆栈将无限增长并在某一时刻溢出。
从日志中删除日志参考或添加一些注释以忽略它
您必须使Logs的'logList'无效,以避免无限循环。 这样尝试
Gson gson = new GsonBuilder().setDateFormat("yyyy-MM-dd'T'HH:mm:ssZ").create();
logs.getLogs.setLogList(null);
return gson.toJson(logs, Logs.class);
您正在获取日志,并且也很想获取日志,显然它在进行连续检索,因此它永远不会结束,因此我建议为Log实体中的以下关系删除“ @ManyToOne”。
@ManyToOne
@JoinColumn(name = "executionid")
private Logs logs;
我知道那是最糟糕的,但我找不到任何办法!
private String convertToMyJSON(Logs logs) {
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ssZ");
String jsonObject = "{"
+ "\"executionId\":\"" + logs.getExecutionId() + "\","
+ "\"startDate\":\"" + sdf.format(logs.getStartDate()) + "\","
+ "\"logList\":[" + getLogString(logs) + "]"
+ "}";
return jsonObject;
}
private String getLogString(Logs logs) {
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ssZ");
String logString = "";
for (Log l : logs.getLogList()) {
logString = logString
+ "{"
+ "\"id\":" + l.getId() + ","
+ "\"executionId\":\"" + logs.getExecutionId() + "\","
+ "\"startDate\":\"" + sdf.format(l.getStartDate()) + "\","
+ "\"endDate\":\"" + sdf.format(l.getEndDate()) + "\","
+ "},";
}
return logString.substring(0, logString.lastIndexOf(","));
}
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