@OrderBy如何運作？

它在以下代碼中不起作用：

Employee.java

package com.semanticbits.pojo;

import java.util.List;

import javax.persistence.CascadeType;

import javax.persistence.Embedded;

import javax.persistence.Entity;

import javax.persistence.GeneratedValue;

import javax.persistence.GenerationType;

import javax.persistence.Id;

import javax.persistence.JoinColumn;

import javax.persistence.OneToMany;

import javax.persistence.OrderBy;

@Entity

public class Employee {

@Id

@GeneratedValue(strategy=GenerationType.IDENTITY)

private int employeeId;

private String name;

private double salary;

@OneToMany(cascade=CascadeType.ALL)

@JoinColumn(name="EMP_ID")

@OrderBy("city DESC")

private List

address;

//setters and getters

public int getEmployeeId() {

return employeeId;

}

public void setEmployeeId(int employeeId) {

this.employeeId = employeeId;

}

public String getName() {

return name;

}

public void setName(String name) {

this.name = name;

}

public double getSalary() {

return salary;

}

public void setSalary(double salary) {

this.salary = salary;

}

public List

getAddress() {

return address;

}

public void setAddress(List

address) {

this.address = address;

}

}

Address.java

package com.semanticbits.pojo;

import javax.persistence.Entity;

import javax.persistence.GeneratedValue;

import javax.persistence.GenerationType;

import javax.persistence.Id;

@Entity

public class Address {

@Id

@GeneratedValue(strategy=GenerationType.IDENTITY)

private int addressId;

private String street;

private String city;

private String state;

private int zipCode;

public String getStreet() {

return street;

}

public void setStreet(String street) {

this.street = street;

}

public String getCity() {

return city;

}

public void setCity(String city) {

this.city = city;

}

public String getState() {

return state;

}

public void setState(String state) {

this.state = state;

}

public int getZipCode() {

return zipCode;

}

public void setZipCode(int zipCode) {

this.zipCode = zipCode;

}

}

persistence.xml中

xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

xsi:schemaLocation="http://java.sun.com/xml/ns/persistence

http://java.sun.com/xml/ns/persistence/persistence_1_0.xsd" version="1.0">

com.semanticbits.pojo.Employee

com.semanticbits.pojo.Address

這是測試類……檢查城市名稱,它不是按照ADDRESS表中的降序順序存儲地址值

JPAOrderByAnnotationTest

package com.semanticbits.test;

import java.util.ArrayList;

import java.util.List;

import javax.persistence.EntityManager;

import javax.persistence.EntityManagerFactory;

import javax.persistence.Persistence;

import com.semanticbits.pojo.Address;

import com.semanticbits.pojo.Employee;

public class JPAOrderByAnnotationTest {

/**

* @param args

*/

public static void main(String[] args) {

EntityManagerFactory factory=Persistence.createEntityManagerFactory("orderbyannotationdemo");

EntityManager manager=factory.createEntityManager();

Employee employee=new Employee();

employee.setName("Shoaib");

employee.setSalary(1452365);

Address addressOffice=new Address();

addressOffice.setCity("Hyderabad");

addressOffice.setStreet("Gachibowli");

addressOffice.setState("AP");

addressOffice.setZipCode(500016);

Address addressHome=new Address();

addressHome.setCity("Noida");

addressHome.setStreet("Chandai Chowk");

addressHome.setState("UP");

addressHome.setZipCode(415608);

Address addressCollege=new Address();

addressCollege.setCity("Antartica");

addressCollege.setState("Canada");

addressCollege.setStreet("New York");

addressCollege.setZipCode(402103);

List

addresses=new ArrayList();

addresses.add(addressHome);

addresses.add(addressOffice);

addresses.add(addressCollege);

employee.setAddress(addresses);

manager.getTransaction().begin();

manager.persist(employee);

manager.getTransaction().commit();

manager.close();

}

}

總結

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