JPA 菜鸟教程 20 JPA2.0 @CollectionTable

GitHub

@CollectionTable

ddl语句

CREATE TABLE `t_employee` (
`id` bigint(20) NOT NULL AUTO_INCREMENT,
`name` varchar(255) DEFAULT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=2 DEFAULT CHARSET=utf8;

CREATE TABLE `t_colors` (
`employee_id` bigint(20) NOT NULL,
`color` varchar(255) DEFAULT NULL,
KEY `FK_105ywqy149ra7e238gil22nvr` (`employee_id`),
CONSTRAINT `FK_105ywqy149ra7e238gil22nvr` FOREIGN KEY (`employee_id`) REFERENCES `t_employee` (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

Employee

package com.jege.jpa;

import java.util.ArrayList;
import java.util.List;

import javax.persistence.CollectionTable;
import javax.persistence.Column;
import javax.persistence.ElementCollection;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.Table;

/**
* @author JE哥
* @email 1272434821@qq.com
* @description:pojo模型
*/
@Entity
@Table(name = "t_employee")
public class Employee {
@Id
@GeneratedValue
private Long id;
private String name;
@ElementCollection
// 一对多集合,如果是JPA1.0必须再写一个Pojo类
@CollectionTable(name = "t_colors", joinColumns = @JoinColumn(name = "employee_id"))
@Column(name = "color")
private List<String> colors = new ArrayList<String>();

public Employee() {

}

public Employee(String name) {
this.name = name;
}

public Long getId() {
return id;
}

public void setId(Long id) {
this.id = id;
}

public String getName() {
return name;
}

public void setName(String name) {
this.name = name;
}

public List<String> getColors() {
return colors;
}

public void setColors(List<String> colors) {
this.colors = colors;
}

}

JPA2Test

package com.jege.jpa;

import java.util.List;

import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.Persistence;
import javax.persistence.Query;

import org.junit.After;
import org.junit.AfterClass;
import org.junit.Before;
import org.junit.BeforeClass;
import org.junit.Test;

public class JPA2Test {

private static EntityManagerFactory entityManagerFactory = null;
private EntityManager entityManager = null;

@BeforeClass
public static void setUpBeforeClass() throws Exception {
entityManagerFactory = Persistence.createEntityManagerFactory("com.jege.jpa");
}

@Before
public void setUp() throws Exception {
entityManager = entityManagerFactory.createEntityManager();
}

@Test
public void persist() throws Exception {
Employee employee = new Employee();
employee.setName("je-ge");

employee.getColors().add("red");
employee.getColors().add("green");
entityManager.getTransaction().begin();
entityManager.persist(employee);
entityManager.getTransaction().commit();
}

@Test
public void find() throws Exception {
persist();
entityManager.clear();

Employee employee = entityManager.find(Employee.class, 1L);
System.out.println(employee.getName());
System.out.println(employee.getColors());

}

@Test
public void query() throws Exception {
persist();
Query query = entityManager.createQuery("select count(o) from Employee o");
Long count = (Long) query.getSingleResult();
System.out.println(count);
}

// public Employee(String name) {
// this.name = name;
// }
@Test
public void query1() throws Exception {
persist();
Query query = entityManager.createQuery("select new Employee(o.name) from Employee o");
List<Employee> employees = query.getResultList();
for (Employee employee : employees) {
System.out.println(employee.getName());
}
}

@Test
public void query2() throws Exception {
persist();
Query query = entityManager.createQuery("select o from Employee o where o.name=?1").setParameter(1, "张三");
List<Employee> employees = query.getResultList();
for (Employee employee : employees) {
System.out.println(employee.getName());
}
}

@Test
public void query3() throws Exception {
persist();
Query query = entityManager.createQuery("select o from Employee o where o.name=:name").setParameter("name", "张三");
List<Employee> employees = query.getResultList();
for (Employee employee : employees) {
System.out.println(employee.getName());
}
}

@Test
public void query4() throws Exception {
persist();
Query query = entityManager.createNamedQuery("getAll");
List<Employee> employees = query.getResultList();
for (Employee employee : employees) {
System.out.println(employee.getName());
}
}

@Test
public void query5() throws Exception {
persist();
Query query = entityManager.createNativeQuery("select * from emp", Employee.class);
List<Employee> employees = query.getResultList();
for (Employee employee : employees) {
System.out.println(employee.getName());
}
}

@After
public void tearDown() throws Exception {
if (entityManager != null && entityManager.isOpen())
entityManager.close();
}

@AfterClass
public static void tearDownAfterClass() throws Exception {
if (entityManagerFactory != null && entityManagerFactory.isOpen())
entityManagerFactory.close();
}

}

源码地址