建设商务网站的经济可行性分析,Wordpress只显示最低价格,手机客户端网站怎么做,西安网站建设 美科动JPA 教程 - JPA 字段映射示例 当将 Java bean 字段映射到数据库列时#xff0c;我们可以选择标记字段#xff0c;标记 getter 方法并标记两者。
标记字段
以下代码来自 Professor.java。
它显示如何将主键列标记为 Java bean 字段标识。
package cn.w3cschool.common;
im…JPA 教程 - JPA 字段映射示例 当将 Java bean 字段映射到数据库列时我们可以选择标记字段标记 getter 方法并标记两者。
标记字段
以下代码来自 Professor.java。
它显示如何将主键列标记为 Java bean 字段标识。
package cn.w3cschool.common;
import javax.persistence.Entity;
import javax.persistence.Id;Entity
public class Professor {Idprivate int id;private String name;private long salary;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;}public long getSalary() {return salary;}public void setSalary(long salary) {this.salary salary;}public String toString() {return Employee id: getId() name: getName() salary: getSalary();}
}下面的代码来自 PersonDaoImpl.java。
package cn.w3cschool.common;import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;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);}PersistenceContextprivate EntityManager em;
}下载 Access_Field.zip
这里是运行代码后的数据库转储。
Table Name: PROFESSORRow:Column Name: ID,Column Type: INTEGER:Column Value: 1Column Name: NAME,Column Type: VARCHAR:Column Value: nameColumn Name: SALARY,Column Type: BIGINT:Column Value: 12345标记属性 getter 方法
以下代码来自 Professor.java。
用于标记要用作数据库表主键列的字段的 Id 注释将添加到 getter 方法。
package cn.w3cschool.common;
import javax.persistence.Entity;
import javax.persistence.Id;Entity
public class Professor {private int id;private String name;private long wage;Idpublic 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;}public long getSalary() {return wage;}public void setSalary(long salary) {this.wage salary;}public String toString() {return Employee id: getId() name: getName() salary: getSalary();}
}下载 Access_Property.zip
以下是在运行上面的代码后的数据库转储。
Table Name: PROFESSORRow:Column Name: ID,Column Type: INTEGER:Column Value: 1Column Name: NAME,Column Type: VARCHAR:Column Value: nameColumn Name: SALARY,Column Type: BIGINT:Column Value: 12345混合标记
使用 JPA我们可以标记字段和 getter 方法。
以下代码来自 Professor.java。
package cn.w3cschool.common;import javax.persistence.Access;
import javax.persistence.AccessType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.Transient;Access(AccessType.FIELD)
Entity
public class Professor {public static String LOCAL_AREA_CODE 999;Idprivate int id;Transientprivate String phoneNum;public int getId() {return id;}public void setId(int id) {this.id id;}public String getPhoneNumber() {return phoneNum;}public void setPhoneNumber(String num) {this.phoneNum num;}Access(AccessType.PROPERTY)Column(name PHONE)protected String getPhoneNumberForDb() {if (null ! phoneNum phoneNum.length() 10)return phoneNum;elsereturn LOCAL_AREA_CODE phoneNum;}protected void setPhoneNumberForDb(String num) {if (num.startsWith(LOCAL_AREA_CODE))phoneNum num.substring(3);elsephoneNum num;}
}下面的代码来自 PersonDaoImpl.java。
package cn.w3cschool.common;import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;import org.springframework.transaction.annotation.Transactional;Transactional
public class PersonDaoImpl {public void test() {Professor emp new Professor();emp.setId(1);emp.setPhoneNumber(123456789);em.persist(emp);}PersistenceContextprivate EntityManager em;
}下载 Access_Mixed.zip
Table Name: PROFESSORRow:Column Name: ID,Column Type: INTEGER:Column Value: 1Column Name: PHONE,Column Type: VARCHAR:Column Value: 999123456789
