这个是查询到实体类
package com.jpa.helloworld;import java.util.Date;
import java.util.HashSet;
import java.util.Set;import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.NamedQuery;
import javax.persistence.OneToMany;
import javax.persistence.Table;
import javax.persistence.TableGenerator;
import javax.persistence.Temporal;
import javax.persistence.TemporalType;
import javax.persistence.Transient;import org.hibernate.annotations.Type;
import org.joda.time.DateTime;
import org.joda.time.LocalDate;@NamedQuery(name="testNamedQuery",query="select c from Customer c")
@Table(name = "JPA_CUSTOMER")
@Entity
public class Customer {private Integer id;private String name;private String email;private int age;private Date birth;private Set<Order> orders = new HashSet<>();private DateTime createDate;private LocalDate lastUpdateDate;private String tran;@TableGenerator(name = "ID_GENDERATOR", pkColumnName = "PK_NAME", pkColumnValue = "CUSTOMER_ID", valueColumnName = "PK_VALUE", allocationSize = 5)@GeneratedValue(strategy = GenerationType.TABLE, generator = "ID_GENDERATOR")@Id@Column(name = "C_ID")public Integer getId() {return id;}public void setId(Integer id) {this.id = id;}//这里的mappedBy是指定由Order的customemr属性维护关联关系//注意！ 在使用mappedBy属性时，不能同时使用@JoinColumn注解
// @JoinColumn(name = "CUSTOMER_ID")@OneToMany(cascade={CascadeType.REMOVE},mappedBy="customer")public Set<Order> getOrders() {return orders;}public void setOrders(Set<Order> orders) {this.orders = orders;}@Column(name = "LAST_NAME", unique = true, length = 20, nullable = false)public String getName() {return name;}public void setName(String name) {this.name = name;}@Column(name = "EMAIL", length = 50)public String getEmail() {return email;}public void setEmail(String email) {this.email = email;}@Column(name = "AGE", length = 3)public int getAge() {return age;}public void setAge(int age) {this.age = age;}@Transientpublic String getTran() {return tran;}public void setTran(String tran) {this.tran = tran;}@Column(name = "BIRTH")@Temporal(TemporalType.DATE)public Date getBirth() {return birth;}public void setBirth(Date birth) {this.birth = birth;}@Column(name = "CREATEDATE")@Type(type = "org.jadira.usertype.dateandtime.joda.PersistentDateTime")public DateTime getCreateDate() {return createDate;}public void setCreateDate(DateTime createDate) {this.createDate = createDate;}@Column(name = "LASTUPDATEDATE")@Type(type = "org.jadira.usertype.dateandtime.joda.PersistentLocalDate")public LocalDate getLastUpdateDate() {return lastUpdateDate;}public void setLastUpdateDate(LocalDate lastUpdateDate) {this.lastUpdateDate = lastUpdateDate;}@Overridepublic String toString() {return "Customer [id=" + id + ", name=" + name + ", email=" + email + ", age=" + age + ", birth=" + birth+ ", orders=" + orders + ", createDate=" + createDate + ", lastUpdateDate=" + lastUpdateDate + ", tran="+ tran + "]";}}
下面是具体的用法
package com.jpa.test;import java.util.List;import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.EntityTransaction;
import javax.persistence.Persistence;
import javax.persistence.Query;import org.junit.After;
import org.junit.Before;
import org.junit.Test;import com.jpa.helloworld.Customer;
import com.jpa.helloworld.Order;public class JPQLTest {private EntityManagerFactory entityManagerFactory;private EntityManager em;private EntityTransaction transaction;@Beforepublic void init() {entityManagerFactory = Persistence.createEntityManagerFactory("jpa-1");em = entityManagerFactory.createEntityManager();transaction = em.getTransaction();transaction.begin();}@Afterpublic void destory() {transaction.commit();em.close();entityManagerFactory.close();}@SuppressWarnings("unchecked")@Testpublic void testNamedQuery() {Query query = em.createNamedQuery("testNamedQuery");List<Customer> cus = query.getResultList();cus.forEach(c -> System.out.println(c));}//利用@NamedQuery注解写在javabean中的sql语句@Testpublic void testQuery() {String jpql = "select c from Customer c where c.id = ?";Query query = em.createQuery(jpql).setParameter(0, 1);Customer customer = (Customer) query.getSingleResult();System.out.println(customer);}//原生的sql查询@Testpublic void testNativeQuery() {String jpql = "select last_name from jpa_customer where c_id = ?";Query query = em.createNativeQuery(jpql).setParameter(1, 1);Object customer = query.getSingleResult();System.out.println(customer);}//使用Order By、Having、Group By@Testpublic void testOrderBy() {String jpql = "select o from Order o group by o.customer.id having count(o) > 1 order by o.customer.id asc ";Query query = em.createQuery(jpql);List<Order> orders = query.getResultList();System.out.println("length:" + orders.size());orders.forEach(o -> System.out.println(o.getCustomer().getId()));}//JPA左外连接@Testpublic void testLeftOutJoinFetch() {String jpql = "select c from Customer c left outer join fetch c.orders where c.id = ?";Query query = em.createQuery(jpql).setParameter(0, 7);Customer customer = (Customer) query.getSingleResult();System.out.println(customer.getName());System.out.println(customer.getOrders().size());}//JPA子查询@SuppressWarnings("unchecked")@Testpublic void testSubQuery() {String jpql = "select o from Order o where o.customer = (select c from Customer c where c.id = ?)";Query query = em.createQuery(jpql).setParameter(0, 1);List<Order> orders = query.getResultList();orders.forEach(o -> System.out.println(o.getoName()));}@Testpublic void testUpdate() {String jpql = "update Customer c set c.name = ? where c.name = ?";Query query = em.createQuery(jpql).setParameter(0, "C-FF").setParameter(1, "C-AA");query.executeUpdate();}
}