惠州JPA ElementCollection字符串映射实例_北大青鸟IT学校

上一篇文章惠州北大青鸟老师给大家分享了JPA ElementCollection字符串映射的知识，下面老师继续给大家分享JPA ElementCollection字符串映射的实例，希望对大家学习Java有帮助。

以下部分显示如何将Java java.util.Map映射到数据库表。

实例

以下代码来自Employee.java。

package cn.w3cschool.common;


import java.util.Map;

import javax.persistence.CollectionTable;
import javax.persistence.Column;
import javax.persistence.ElementCollection;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.ManyToOne;
import javax.persistence.MapKeyColumn;

@Entitypublic class Employee {
   @Id @GeneratedValue(strategy=GenerationType.IDENTITY)    private int id;    private String name;    private long salary;

   @ElementCollection
   @CollectionTable(name="EMP_PHONE")
   @MapKeyColumn(name="PHONE_TYPE")
   @Column(name="PHONE_NUM")    private Map<String, String> phoneNumbers;
           
   @ManyToOne    private Department department;    
   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 Department getDepartment() {
       return department;
   }    
   public void setDepartment(Department department) {
       this.department = department;
   }    public Map<String, String> getPhoneNumbers() {
       return phoneNumbers;
   }    public void setPhoneNumbers(Map<String, String> phoneNumbers) {
       this.phoneNumbers = phoneNumbers;
   }    public String toString() {
       StringBuffer aBuffer = new StringBuffer("Employee ");
       aBuffer.append(" id: ");
       aBuffer.append(id);
       aBuffer.append(" with dept: ");        if(null != department) {
           aBuffer.append(department.getName());
       }
       aBuffer.append(" phoneNumbers: ");        for (Map.Entry e : phoneNumbers.entrySet()) {
           aBuffer.append(e.getKey() + "[" + e.getValue() + "] ");
       }        
       return aBuffer.toString();
   }
}

这里是数据库表转储。

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

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





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

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

   Column Name: SALARY,
   Column Type: BIGINT:
   Column Value: 0

   Column Name: DEPARTMENT_ID,
   Column Type: INTEGER:
   Column Value: 1





Table Name: EMP_PHONE

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