EntitlementTransaction的結構：
@Entity
@Table(name = EntitlementTransactionConstant.TABLE_ENTITLEMENT_TRANSACTION)
public class EntitlementTransaction implements Serializable {
private static final long serialVersionUID = 1L;
@Id
@GeneratedValue(generator = "system-uuid")
@Column(name = EntitlementTransactionConstant.GUID )
private String guid;
@Column(name = EntitlementTransactionConstant.TRANSACTIONID,nullable = false)
private String transactionID;
@Column(name = EntitlementTransactionConstant.ENTITLEMENTNAME)
private String entitlementName;
@Column(name = EntitlementTransactionConstant.TYPE)
private String type;
@Column(name = EntitlementTransactionConstant.TENANTID)
private long tenantID;
@Column(name = EntitlementTransactionConstant.CUSTOMER)
private String customer;
@Column(name = EntitlementTransactionConstant.STORAGE)
private long storage;
@Column(name = EntitlementTransactionConstant.CPUCORE)
private long cpuCore;
@Column(name = EntitlementTransactionConstant.USERCOUNT)
private long userCount;
@Column(name = EntitlementTransactionConstant.STATUS)
private String status;
@ManyToOne(fetch = FetchType.LAZY)
@JoinColumn(name = EntitlementTransactionConstant.ENTITLEMENTID)
private EntitlementMaster entitlementMaster ;
@Entity
@Table(name = EntitlementMasterConstant.TABLE_Master_Constant)
public class EntitlementMaster implements Serializable {
private static final long serialVersionUID = 1L;
@Id
@GeneratedValue(generator = "system-uuid")
@Column(name = EntitlementMasterConstant.GUID)
private String guid;
@Column(name = EntitlementMasterConstant.ENTITLEMENTNAME)
private String entitlementName;
@Column(name = EntitlementMasterConstant.ENTITLEMENTGUID)
private String entitlementID;
@Column(name = EntitlementMasterConstant.TYPE)
private String type;
@Column(name = EntitlementMasterConstant.TENANTID)
private long tenantID;
@Column(name = EntitlementMasterConstant.CUSTOMER)
private String customer;
@Column(name = EntitlementMasterConstant.STORAGE)
private long storage;
@Column(name = EntitlementMasterConstant.CPUCORE)
private long cpuCore;
@Column(name = EntitlementMasterConstant.USERCOUNT)
private long userCount;
@Column(name = EntitlementMasterConstant.OPERANT)
private String Operant;
@OneToMany(mappedBy = "entitlementMaster", fetch = FetchType.LAZY,cascade = CascadeType.ALL)
private Set<EntitlementTransaction> entitlementTransaction = new HashSet<>();
EntitleMaster的結構：
@Entity
@Table(name = EntitlementMasterConstant.TABLE_Master_Constant)
public class EntitlementMaster implements Serializable {
private static final long serialVersionUID = 1L;
@Id
@GeneratedValue(generator = "system-uuid")
@Column(name = EntitlementMasterConstant.GUID)
private String guid;
@Column(name = EntitlementMasterConstant.ENTITLEMENTNAME)
private String entitlementName;
@Column(name = EntitlementMasterConstant.ENTITLEMENTGUID)
private String entitlementID;
@Column(name = EntitlementMasterConstant.TYPE)
private String type;
@Column(name = EntitlementMasterConstant.TENANTID)
private long tenantID;
@Column(name = EntitlementMasterConstant.CUSTOMER)
private String customer;
@Column(name = EntitlementMasterConstant.STORAGE)
private long storage;
@Column(name = EntitlementMasterConstant.CPUCORE)
private long cpuCore;
@Column(name = EntitlementMasterConstant.USERCOUNT)
private long userCount;
@Column(name = EntitlementMasterConstant.OPERANT)
private String Operant;
@OneToMany(mappedBy = "entitlementMaster", fetch = FetchType.LAZY,cascade = CascadeType.ALL)
private Set<EntitlementTransaction> entitlementTransaction = new HashSet<>();
這兩張表通過EntitlementID字段來維持了雙向映射的關系霎奢，在通過JPA對EntitlementTransaction表進行findALL()操作時帖世，會因為這種雙向映射關系導致反復查詢同一條數據的情況秃臣，先來看數據庫中的數據：
數據庫中的數據
而查詢出來的數據卻是這樣的：
查詢出的數據
這個時候的Service層的代碼是這樣的：
@Autowired
EntitlementTransactionRepository entitlementTransactionRepository;
@Override
public List<EntitlementTransaction> getAll(){
return entitlementTransactionRepository.findAll();
}
如何解決這個問題呢梳毙？
首先新建EntitlementTransactionDtoNew類：
public class EntitlementTransactionDtoNew
{
private String guid;
private String entitlementID;
private String transactionID;
private String entitlementName;
private String type;
private long tenantID;
private String customer;
private long storage;
private long cpuCore;
private long userCount;
private String status;
getter and setter......
}
改寫Service中的查詢代碼：
@Override
public List<EntitlementTransactionDtoNew> getAll(){
List<EntitlementTransactionDtoNew> entitlementTransactionDtoNews = new ArrayList<>();
for(EntitlementTransaction entitlementTransaction : entitlementTransactionRepository.findAll()){
EntitlementTransactionDtoNew entitlementTransactionDto = new EntitlementTransactionDtoNew();
entitlementTransactionDto.setGuid(entitlementTransaction.getGuid());
entitlementTransactionDto.setEntitlementID(entitlementTransaction.getEntitlementMaster().getEntitlementID());
entitlementTransactionDto.setTransactionID(entitlementTransaction.getTransactionID());
entitlementTransactionDto.setEntitlementName(entitlementTransaction.getEntitlementName());
entitlementTransactionDto.setType(entitlementTransaction.getType());
entitlementTransactionDto.setTenantID(entitlementTransaction.getTenantID());
entitlementTransactionDto.setCustomer(entitlementTransaction.getCustomer());
entitlementTransactionDto.setStorage(entitlementTransaction.getStorage());
entitlementTransactionDto.setCpuCore(entitlementTransaction.getCpuCore());
entitlementTransactionDto.setUserCount(entitlementTransaction.getUserCount());
entitlementTransactionDto.setStatus(entitlementTransaction.getStatus());
entitlementTransactionDtoNews.add(entitlementTransactionDto);
}
return entitlementTransactionDtoNews;
}
通過這樣的方式就可以打破雙向映射導致的反復查詢，于是我們得到如下的正確的findAll結果如圖：
正確結果
這個問題是由JPA導致的般婆，在同事的幫助下用這樣的方式解決了該問題到腥，希望JPA以后能夠修復這個BUG。
