Eclipselink Jpa 之 JPQL动态查询与静态查询

最新推荐文章于 2024-05-11 11:02:38 发布

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最新推荐文章于 2024-05-11 11:02:38 发布

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分类专栏： java中间件

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本文展示了如何在Eclipselink JPA中使用JPQL进行动态查询和静态查询。通过示例代码，我们可以看到动态查询和静态查询返回了相同的结果，包括学生对象的详细信息。动态查询直接在Service层构建Query，而静态查询则利用@Entity的@NamedQuery注解预先定义查询。

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动态查询:
package com.atsico.pojo01;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
import lombok.experimental.Accessors;

import javax.persistence.*;

@Data
@NoArgsConstructor
@AllArgsConstructor
@Accessors(chain = true)
@Entity
@Table(name = “student”)
public class Student {

@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private int id;
private String name;
private int age;
private String classname;

}

<?xml version="1.0" encoding="UTF-8"?> org.eclipse.persistence.jpa.PersistenceProvider com.atsico.pojo01.Student

    <properties>
        <!-- 连接数据库的基本信息 -->
        <property name="javax.persistence.jdbc.driver"
                  value="com.mysql.cj.jdbc.Driver"/>
        <property name="javax.persistence.jdbc.url"
                  value="jdbc:mysql://localhost:3306/jpadb?useSSL=false&amp;serverTimezone=Asia/Shanghai"/>
        <property name="javax.persistence.jdbc.user" value="root"/>
        <property name="javax.persistence.jdbc.password"
                  value="root"/>
        <property name="eclipselink.logging.level" value="all"/>
        <property name="eclipselink.ddl-generation"
                  value="create-or-extend-tables"/>
        <property name="eclipselink.show_sql" value="true"/>
    </properties>
</persistence-unit>

package com.atsico.service;

import com.atsico.pojo01.Student;
import org.junit.Test;

import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.Persistence;
import javax.persistence.Query;
import java.util.List;

public class Jpa_Jpql_Test {

@Test/*动态查询*/
public void test_select_01() {
    EntityManagerFactory emf =
            Persistence.createEntityManagerFactory("myPersistUnit");
    EntityManager em = emf.createEntityManager();
    /*动态查询*/
    Query q = em.createQuery("select  s from Student s");
    @SuppressWarnings("unchecked")
    List<Student> resultList = q.getResultList();
    for (Student stu : resultList) {
        System.out.println(stu);
    }
}

}
动态查询结果：
Student(id=1, name=Sico, age=11, classname=102)
Student(id=2, name=Tomy, age=10, classname=107)
Student(id=3, name=Lily, age=13, classname=108)
Student(id=4, name=Hong, age=12, classname=101)

/****************************************************************************************/
静态查询:
package com.atsico.pojo01;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
import lombok.experimental.Accessors;

import javax.persistence.*;

@Data
@NoArgsConstructor
@AllArgsConstructor
@Accessors(chain = true)
@Entity
@Table(name = “student”)
@NamedQuery(name = “find Student”, query = "select s from Student s ")
public class Student {

@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private int id;
private String name;
private int age;
private String classname;

}

<?xml version="1.0" encoding="UTF-8"?> org.eclipse.persistence.jpa.PersistenceProvider

    <class>com.atsico.pojo01.Student</class>

    <properties>
        <!-- 连接数据库的基本信息 -->
        <property name="javax.persistence.jdbc.driver"
                  value="com.mysql.cj.jdbc.Driver"/>
        <property name="javax.persistence.jdbc.url"
                  value="jdbc:mysql://localhost:3306/jpadb?useSSL=false&amp;serverTimezone=Asia/Shanghai"/>
        <property name="javax.persistence.jdbc.user" value="root"/>
        <property name="javax.persistence.jdbc.password"
                  value="root"/>
        <property name="eclipselink.logging.level" value="all"/>
        <property name="eclipselink.ddl-generation"
                  value="create-or-extend-tables"/>
        <property name="eclipselink.show_sql" value="true"/>
    </properties>
</persistence-unit>

package com.atsico.service;

import com.atsico.pojo01.Student;
import org.junit.Test;

import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.Persistence;
import javax.persistence.Query;
import java.util.List;

public class Jpa_Jpql_Test {

@Test/*静态态查询*/
public void test_select_02() {
    EntityManagerFactory emf =
            Persistence.createEntityManagerFactory("myPersistUnit");
    EntityManager em = emf.createEntityManager();
    /*动态查询*/
    Query q = em.createNamedQuery("find Student");
    @SuppressWarnings("unchecked")
    List<Student> resultList = q.getResultList();
    for (Student stu : resultList) {
        System.out.println(stu);
    }
}

}

静态查询结果：

Student(id=1, name=Sico, age=11, classname=102)
Student(id=2, name=Tomy, age=10, classname=107)
Student(id=3, name=Lily, age=13, classname=108)
Student(id=4, name=Hong, age=12, classname=101)