JPA Transient示例

JPA教程 - JPA Transient示例

如果我們不想將屬性保存到數(shù)據(jù)庫，我們可以使用@Transient注釋標(biāo)記該字段。

例子

以下代碼來自Professor.java。

package cn.w3cschool.common;
import java.util.Locale;

import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.Transient;
@Entity

public class Professor {
  @Id
  private int id;
  private String name;
  private long salary;
  @Transient 
  private String convertedName;

  public int getId() {
      return id;
  }
  
  public void setId(int id) {
      this.id = id;
  }
  
  public String getName() {
      return name;
  }
  
  public void setName(String name) {
      this.name = name;
      convertedName = convertName(name);
  }

  public long getSalary() {
      return salary;
  }

  public void setSalary(long salary) {
      this.salary = salary;
  }

  public String getConvertedName() {
      return convertedName;
  }

  public String toString() {
      return "Employee " + " id: " + getId() + " name: " + getName() + " converted name: " + getConvertedName() + " salary: " + getSalary();
  }

  protected String convertName(String name) {
      // Convert to upper case Canadian...
      return name.toUpperCase(Locale.CANADA);
  }
}

下面的代碼來自PersonDaoImpl.java。

package cn.w3cschool.common;

import java.util.List;

import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;
import javax.persistence.TypedQuery;

import org.springframework.transaction.annotation.Transactional;

@Transactional
public class PersonDaoImpl {
  public void test() {

    Professor emp = new Professor();
    emp.setId(1);
    emp.setName("name");
    emp.setSalary(12345);
    em.persist(emp);

  }

  @PersistenceContext
  private EntityManager em;
}

以下是數(shù)據(jù)庫轉(zhuǎn)儲(chǔ)。

Table Name: PROFESSOR
 Row:
    Column Name: ID,
    Column Type: INTEGER:
    Column Value: 1

    Column Name: NAME,
    Column Type: VARCHAR:
    Column Value: name

    Column Name: SALARY,
    Column Type: BIGINT:
    Column Value: 12345