笔记：Hibernate 持久化类标注示例-双向1-N关系映射

Posted 2020-08-29 追寻自由的路途

• 1-N关系的1端持久化类

  package org.drsoft.hibernate.model.oneToMany;

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  import java.util.Date;

  import java.util.Set;

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  import javax.persistence.*;

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  @Entity

  @Table(name = "OneToMany_One")

  public class OneToManyForOneModel {

  @Id

  @Column(name = "Record_ID")

  @GeneratedValue(strategy = GenerationType.IDENTITY)

  private int recordID;

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  @Column(name = "Total_Trade_Amt")

  private long totalTradeAmt;

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  @Column(name = "Modify_Time")

  private Date modifyTime;

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  @Column(name = "Create_Time", insertable = false, updatable = false)

  private Date createTime;

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  @OneToMany(cascade = {

  CascadeType.PERSIST }, fetch = FetchType.LAZY, targetEntity = OneToManyForManyModel.class, orphanRemoval = false,mappedBy="oneToManyForOneModel")

  private Set<OneToManyForManyModel> details;

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  省略setter和getter

  }

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• 1-N关系的N端持久化类

  package org.drsoft.hibernate.model.oneToMany;

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  import java.util.Date;

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  import javax.persistence.*;

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  @Entity

  @Table(name = "OneToMany_Many")

  public class OneToManyForManyModel {

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  @Id

  @Column(name = "Detail_ID")

  @GeneratedValue(strategy = GenerationType.IDENTITY)

  private int detailID;

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  @Column(name = "Trade_Amt")

  private long tradeAmt;

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  @Column(name = "Create_Time", insertable = false, updatable = false)

  private Date createTime;

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  @ManyToOne

  @JoinColumn(name = "Ref_Record_ID", referencedColumnName = "Record_ID")

  private OneToManyForOneModel oneToManyForOneModel;

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  省略setter和getter

  }

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• 测试调用

  package org.drsoft.hibernate.manager.oneToMany;

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  import java.util.*;

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  import org.drsoft.hibernate.model.oneToMany.*;

  import org.drsoft.utils.hibernateUtils;

  import org.hibernate.Session;

  import org.hibernate.Transaction;

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  public class OneToManyManager {

  public static void main(String[] args) {

  Session curSession = hibernateUtils.openSession();

  Transaction curTransaction = null;

  Calendar calendar = Calendar.getInstance(Locale.CHINA);

  try {

  System.out.println("#1 创建 One 和 Many数据");

  // #1 创建 One 和 Many数据

  OneToManyForOneModel oneToManyForOneModel = new OneToManyForOneModel();

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  long totalTradeAmt = 0;

  for (int i = 0; i < 5; i++) {

  OneToManyForManyModel oneToManyForManyModel = new OneToManyForManyModel();

  oneToManyForManyModel.setTradeAmt(calendar.get(Calendar.SECOND) + i);

  totalTradeAmt = totalTradeAmt + oneToManyForManyModel.getTradeAmt();

  if (oneToManyForOneModel.getDetails() == null) {

  oneToManyForOneModel.setDetails(new HashSet<OneToManyForManyModel>());

  System.out.println("创建 HashSet<OneToManyForManyModel>()");

  }

  oneToManyForOneModel.getDetails().add(oneToManyForManyModel);

  }

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  oneToManyForOneModel.setTotalTradeAmt(totalTradeAmt);

  oneToManyForOneModel.setModifyTime(new Date());

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  curTransaction = hibernateUtils.beginTransaction(curSession);

  curSession.persist(oneToManyForOneModel);

  curTransaction.commit();

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  System.out.println("#2 查询 One 数据");

  // #2 查询 One 数据

  oneToManyForOneModel = (OneToManyForOneModel) curSession.load(OneToManyForOneModel.class, new Integer(1));

  System.out.println("OneToManyForOneModel RecordID=" + oneToManyForOneModel.getRecordID()

  + "\tTotalTradeAmt=" + oneToManyForOneModel.getTotalTradeAmt());

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  Set<OneToManyForManyModel> details = oneToManyForOneModel.getDetails();

  Iterator<OneToManyForManyModel> it = details.iterator();

  while (it.hasNext()) {

  OneToManyForManyModel obj = it.next();

  System.out.println(

  "OneToManyForManyModel DetailID=" + obj.getDetailID() + "\tTradeAmt=" + obj.getTradeAmt());

  }

  } catch (Exception e) {

  if (curTransaction != null && curTransaction.isActive()) {

  curTransaction.rollback();

  }

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  throw e;

  } finally {

  if (curSession != null) {

  curSession.close();

  }

  }

  }

  }

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