SpingDataJpa

SpringDataJpa

---

簡介

Spring Data 是爲數據訪問提供一種熟悉且一致的基於Spring的編程模型，同時仍然保留底層數據存儲的特​​殊特性。它可以輕鬆使用數據訪問技術，可以訪問關係和非關係數據庫。

Spring Data 又包含多個子項目：

• Spring Data JPA
• Spirng Data Mongo DB
• Spring Data Redis
• Spring Data Solr

傳統數據庫訪問數據庫

使用原始JDBC方式進行數據庫操作
創建數據表

jdbc工具類

package com.JDBC.util;
import java.io.InputStream;
import java.sql.*;
import java.util.Properties;

public class JDBCUtil {

    public static Connection getConnection() throws Exception {

        InputStream inputStream = JDBCUtil.class.getClassLoader().getResourceAsStream("db.properties");
        Properties properties = new Properties();
        properties.load(inputStream);

        String url = properties.getProperty("jdbc.url");
        String user = properties.getProperty("jdbc.user");
        String password = properties.getProperty("jdbc.password");
        String driverClass = properties.getProperty("jdbc.driverClass");
        Class.forName(driverClass);
        Connection connection = DriverManager.getConnection(url, user, password);
        return connection;
    }

    public static void release(ResultSet resultSet, Statement statement,Connection connection) {
        if (resultSet != null) {
            try {
                resultSet.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        if (statement != null) {
            try {
                statement.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        if (connection != null) {
            try {
                connection.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }
}

建立POJO

package com.xx;

public class Student {

    private int id;

    private String name;

    private  int age;

    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 int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }
}

package com.xx.dao;

import com.xx.domain.Student;
import com.xx.util.JDBCUtil;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.util.ArrayList;
import java.util.List;

public class StudentDAOImpl implements StudentDAO{

    /**
     * 查詢學生
     */
    @Override
    public List<Student> query() {

        List<Student> students = new ArrayList<>();

        Connection connection = null;
        PreparedStatement preparedStatement = null;
        ResultSet resultSet = null;
        String sql = "select * from student";
        try {
            connection = JDBCUtil.getConnection();
            preparedStatement = connection.prepareStatement(sql);
            resultSet = preparedStatement.executeQuery();

            Student student = null;
            while (resultSet.next()) {
                int id = resultSet.getInt("id");
                String name = resultSet.getString("name");
                int age = resultSet.getInt("age");

                student = new Student();
                student.setId(id);
                student.setAge(age);
                student.setName(name);

                students.add(student);
            }
        } catch (Exception e) {
            e.printStackTrace();
        }finally {
            JDBCUtil.release(resultSet,preparedStatement,connection);
        }
        return students;
    }

    /**
     * 添加學生
     */
    @Override
    public void save(Student student) {
        Connection connection = null;
        PreparedStatement preparedStatement = null;
        ResultSet resultSet = null;
        String sql = "insert into student(name,age) values (?,?)";
        try {
            connection = JDBCUtil.getConnection();
            preparedStatement = connection.prepareStatement(sql);
            preparedStatement.setString(1, student.getName());
            preparedStatement.setInt(2,student.getAge());
            preparedStatement.executeUpdate();

        } catch (Exception e) {
            e.printStackTrace();
        }finally {
            JDBCUtil.release(resultSet,preparedStatement,connection);
        }
    }
}

使用Spring JDBC Template對數據庫進行操作

• 創建spring配置文件：

<?xml version="1.0" encoding="UTF-8"?>

<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.0.xsd">

    <context:property-placeholder location="classpath:db.properties"/>

    <bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
        <property name="driverClassName" value="${jdbc.driverClass}"/>
        <property name="username" value="${jdbc.user}"/>
        <property name="password" value="${jdbc.password}"/>
        <property name="url" value="${jdbc.url}"/>
    </bean>

    <bean id="jdbcTemplate" class="org.springframework.jdbc.core.JdbcTemplate">
        <property name="dataSource" ref="dataSource"/>
    </bean>
    <bean id="studentDAO" class="com.zzh.dao.StudentDAOSpringJdbcImpl">
        <property name="jdbcTemplate" ref="jdbcTemplate"/>
    </bean>
</beans>

• 編寫查詢學生和保存學生的方法

package com.xx.dao;

import com.xx.domain.Student;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.jdbc.core.RowCallbackHandler;

import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;


public class StudentDAOSpringJdbcImpl implements StudentDAO{

    private JdbcTemplate jdbcTemplate;

    public void setJdbcTemplate(JdbcTemplate jdbcTemplate) {
        this.jdbcTemplate = jdbcTemplate;
    }


    @Override
    public List<Student> query() {
        final List<Student> students = new ArrayList<>();
        String sql = "select * from student";

        jdbcTemplate.query(sql, new RowCallbackHandler() {
            @Override
            public void processRow(ResultSet resultSet) throws SQLException {
                int id = resultSet.getInt("id");
                String name = resultSet.getString("name");
                int age = resultSet.getInt("age");

                Student student = new Student();
                student.setId(id);
                student.setAge(age);
                student.setName(name);

                students.add(student);
            }
        });
        return students;
    }

    @Override
    public void save(Student student) {

        String sql = "insert into student(name,age) values (?,?)";
        jdbcTemplate.update(sql, new Object[]{student.getName(), student.getAge()});
    }
}

弊端分析

• DAO中有太多的代碼

• DAOImpl有大量重複代碼

• 開發分頁或者其他功能還要重新封裝

SpringData

例：

• 添加pom依賴

<dependency>
    <groupId>org.springframework.data</groupId>
    <artifactId>spring-data-jpa</artifactId>
    <version>1.8.0.RELEASE</version>
</dependency>
<dependency>
    <groupId>org.hibernate</groupId>
    <artifactId>hibernate-entitymanager</artifactId>
    <version>4.3.6.Final</version>
</dependency>

• 創建一個新的spring配置文件

<?xml version="1.0" encoding="UTF-8"?>

<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:tx="http://www.springframework.org/schema/tx"
       xmlns:jpa="http://www.springframework.org/schema/data/jpa"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/data/jpa http://www.springframework.org/schema/data/jpa/spring-jpa-1.3.xsd
        http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-4.0.xsd
        http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.0.xsd">

    <context:property-placeholder location="classpath:db.properties"/>

    <bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
        <property name="driverClassName" value="${jdbc.driverClass}"/>
        <property name="username" value="${jdbc.user}"/>
        <property name="password" value="${jdbc.password}"/>
        <property name="url" value="${jdbc.url}"/>
    </bean>

    <!-- 配置EntityManagerFactory-->
    <bean id="entityManagerFactory" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
        <property name="dataSource" ref="dataSource"/>
        <property name="jpaVendorAdapter">
            <bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter"/>

        </property>
        <property name="packagesToScan" value="com.zzh"/>

        <property name="jpaProperties">
            <props>
                <prop key="hibernate.ejb.naming_strategy">org.hibernate.cfg.ImprovedNamingStrategy</prop>
                <prop key="hibernate.dialect">org.hibernate.dialect.MySQL5InnoDBDialect</prop>
                <prop key="hibernate.show_sql">true</prop>
                <prop key="hibernate.format_sql">true</prop>
                <prop key="hibernate.hbm2ddl.auto">update</prop>
            </props>
        </property>
    </bean>

    <!--事務管理器-->
    <bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager">
        <property name="entityManagerFactory" ref="entityManagerFactory"/>
    </bean>

    <!--支持註解的事物-->
    <tx:annotation-driven transaction-manager="transactionManager"/>

    <!--spring data-->
    <jpa:repositories base-package="com.zzh" entity-manager-factory-ref="entityManagerFactory"/>

    <context:component-scan base-package="com.zzh"/>
</beans>

LocalContainerEntityMangaerFactoryBean:

適用於所有環境的FactoryBean，能全面控制EntityMangaerFactory配置，非常適合那種需要細粒度定製的環境。

jpaVendorAdapter：

用於設置JPA實現廠商的特定屬性，如設置hibernate的是否自動生成DDL的屬性generateDdl，這些屬性是廠商特定的。目前spring提供HibernateJpaVendorAdapter，OpenJpaVendorAdapter，EclipseJpaVendorAdapter，TopLinkJpaVenderAdapter四個實現。

jpaProperties：

指定JPA屬性；如Hibernate中指定是否顯示SQL的“hibernate.show_sql”屬性。

• 建立實體類Employee:

package com.xx;


public class Employee {

    private  Integer id;

    private String name;

    private Integer age;

    public Integer getId() {
        return id;
    }

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

    public String getName() {
        return name;
    }

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

    public Integer getAge() {
        return age;
    }

    public void setAge(Integer age) {
        this.age = age;
    }

}

• 自定義接口並繼承Repository 接口
  繼承的Repository接口泛型裏的第一個參數是要操作的對象，即Employee；第二個參數是主鍵id的類型，即Integer。
  方法即爲根據名字找員工，這個接口是不用寫實現類的。爲什麼可以只繼承接口定義了方法就行了呢，因爲spring data底層會根據一些規則來進行相應的操作。
  所以方法的名字是不能隨便寫的，不然就無法執行想要的操作。

package com.xx.repository;

import com.zzh.domain.Employee;
import org.springframework.data.repository.Repository;

public interface EmployeeRepository extends Repository<Employee,Integer>{
    Employee findByName(String name);
}

• 創建測試類
  findByName方法體中先不用寫，直接執行空的測試方法，我們的Employee表就自動被創建了，此時表中沒有數據，向裏面添加一條數據用於測試：

package com.xx.repository;


import com.xx.domain.Employee;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class EmployeeRepositoryTest {

    private ApplicationContext ctx = null;

    private EmployeeRepository employeeRepository = null;

    @Before
    public void setUp() throws Exception {
        ctx = new ClassPathXmlApplicationContext("beans-new.xml");
        employeeRepository = ctx.getBean(EmployeeRepository.class);
    }

    @After
    public void tearDown() throws Exception {
        ctx = null;
    }

    @Test
    public void findByName() throws Exception {
        Employee employee = employeeRepository.findByName("zhangsan");
        System.out.println("id:" + employee.getId() + " name:" + employee.getName() + " age:" + employee.getAge());
    }

}

再執行測試方法中的內容：

Repository接口

• Repository接口是Spring Data的核心接口，不提供任何方法
• 使用 @ RepositoryDefinition註解跟繼承Repository是同樣的效果，例如 @ RepositoryDefinition（domainClass = Employee.class, idClass = Integer.class)
• Repository接口定義爲：public interface Repository

Repository的子接口

• CrudRepository ：繼承 Repository，實現了CRUD相關的方法。
• PagingAndSortingRepository : 繼承 CrudRepository，實現了分頁排序相關的方法。
• JpaRepository ：繼承 PagingAndSortingRepository ，實現了JPA規範相關的方法。

Repository中查詢方法定義規則
上面一個例子中使用了findByName作爲方法名進行指定查詢，但是如果把名字改爲其他沒有規則的比如test就無法獲得正確的查詢結果。

有如下規則：

最右邊是sql語法，中間的就是spring data操作規範，現在寫一些小例子來示範一下：

先在employee表中初始化了一些數據：

在繼承了Repository接口的EmployeeRepository接口中新增一個方法：

條件是名字以test開頭，並且年齡小於22歲，在測試類中進行測試：

得到結果：

在換一個名字要在某個範圍以內並且年齡要小於某個值：
測試類：

得到結果，只有test1和test2，因爲在test1，test2和test3裏面，年齡還要小於22，所以test3被排除了：

弊端分析
對於按照方法名命名規則來使用的弊端在於：

1. 方法名會比較長
2. 對於一些複雜的查詢很難實現

Query註解

• 只需要將 @ Query標記在繼承了Repository的自定義接口的方法上，就不再需要遵循查詢方法命名規則。
• 支持命名參數及索引參數的使用
• 本地查詢

案例

• 查詢Id最大的員工信息

 @Query("select o from Employee o where id=(select max(id) from Employee t1)")
    Employee getEmployeeById();

注意： Query語句中第一個Employee是類名

測試類：

@Test
    public void getEmployeeByMaxId() throws Exception {
        Employee employee = employeeRepository.getEmployeeByMaxId();
        System.out.println("id:" + employee.getId() + " name:" + employee.getName() + " age:" + employee.getAge());
    }

• 根據佔位符進行查詢

注意： 佔位符從1開始

@Query("select o from Employee o where o.name=?1 and o.age=?2")
    List<Employee> queryParams1(String name, Integer age);

測試方法：

@Test
    public void queryParams1() throws Exception {
        List<Employee> employees = employeeRepository.queryParams1("zhangsan", 20);
        for (Employee employee : employees) {
            System.out.println("id:" + employee.getId() + " name:" + employee.getName() + " age:" + employee.getAge());
        }
    }

• 根據命名參數的方式

  @Query("select o from Employee o where o.name=:name and o.age=:age")
    List<Employee> queryParams2(@Param("name") String name, @Param("age") Integer age);

• like查詢語句

@Query("select o from Employee o where o.name like %?1%")
    List<Employee> queryLike1(String name);
@Test
    public void queryLike1() throws Exception {
        List<Employee> employees = employeeRepository.queryLike1("test");
        for (Employee employee : employees) {
            System.out.println("id:" + employee.getId() + " name:" + employee.getName() + " age:" + employee.getAge());
        }
    }

• like語句使用命名參數

@Query("select o from Employee o where o.name like %:name%")
    List<Employee> queryLike2(@Param("name") String name);

本地查詢

所謂本地查詢，就是使用原生的sql語句進行查詢數據庫的操作。但是在Query中原生態查詢默認是關閉的,需要手動設置爲true：

@Query(nativeQuery = true, value = "select count(1) from employee")
    long getCount();

更新操作整合事物使用

• 在DAO中定義方法根據Id來更新年齡（Modifying註解代表允許修改）

 @Modifying
    @Query("update Employee o set o.age = :age where o.id = :id")
    void update(@Param("id") Integer id, @Param("age") Integer age);

要注意，執行更新或者刪除操作是需要事物支持，所以通過service層來增加事物功能,在update方法上添加Transactional註解。

package com.xx.service;

import com.xx.repository.EmployeeRepository;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

@Service
public class EmployeeService {

    @Autowired
    private EmployeeRepository employeeRepository;

    @Transactional
    public void update(Integer id, Integer age) {
        employeeRepository.update(id,age);
    }
}

• 刪除操作

  刪除操作同樣需要Query註解，Modifying註解和Transactional註解

 @Modifying
    @Query("delete from Employee o where o.id = :id")
    void delete(@Param("id") Integer id);


    @Transactional
    public void delete(Integer id) {
        employeeRepository.delete(id);
    }

CrudRepository接口

• 創建接口繼承CrudRepository

package com.xx.repository;


import com.xx.domain.Employee;
import org.springframework.data.repository.CrudRepository;

public interface EmployeeCrudRepository extends CrudRepository<Employee,Integer>{

}

• 在service層中調用

 @Autowired
    private EmployeeCrudRepository employeeCrudRepository;

• 存入多個對象

  @Transactional
    public void save(List<Employee> employees) {
        employeeCrudRepository.save(employees);
    }

• 創建測試類,將要插入的100條記錄放在List中：

package com.xx.repository;

import com.xx.domain.Employee;
import com.xx.service.EmployeeService;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;

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


@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration({"classpath:beans-new.xml"})
public class EmployeeCrudRepositoryTest {

    @Autowired
    private EmployeeService employeeService;

    @Test
    public void testSave() {
        List<Employee> employees = new ArrayList<>();

        Employee employee = null;
        for (int i = 0; i < 100; i++) {
            employee = new Employee();
            employee.setName("test" + i);
            employee.setAge(100 - i);
            employees.add(employee);
        }
        employeeService.save(employees);
    }
}

執行後：

CrudRepository總結

可以發現在自定義的EmployeeCrudRepository中，只需要聲明接口並繼承CrudRepository就可以直接使用了。

PagingAndSortingRepository接口

• 該接口包含分頁和排序的功能
• 帶排序的查詢：findAll(Sort sort)

• 帶排序的分頁查詢：findAll(Pageable pageable)

  自定義接口

package com.xx.repository;


import com.xx.domain.Employee;
import org.springframework.data.repository.PagingAndSortingRepository;

public interface EmployeePagingAndSortingRepository extends PagingAndSortingRepository<Employee, Integer> {

}

測試類：

分頁

package com.xx.repository;

import com.xx.domain.Employee;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.domain.Page;
import org.springframework.data.domain.PageRequest;
import org.springframework.data.domain.Pageable;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration({"classpath:beans-new.xml"})
public class EmployeePagingAndSortingRepositoryTest {

    @Autowired
    private EmployeePagingAndSortingRepository employeePagingAndSortingRepository;

    @Test
    public void testPage() {

        //第0頁，每頁5條記錄
        Pageable pageable = new PageRequest(0, 5);
        Page<Employee> page = employeePagingAndSortingRepository.findAll(pageable);

        System.out.println("查詢的總頁數："+ page.getTotalPages());
        System.out.println("總記錄數："+ page.getTotalElements());
        System.out.println("當前第幾頁："+ page.getNumber()+1);
        System.out.println("當前頁面對象的集合："+ page.getContent());
        System.out.println("當前頁面的記錄數："+ page.getNumberOfElements());
    }

}

排序：

在PageRequest的構造函數裏還可以傳入一個參數Sort，而Sort的構造函數可以傳入一個Order，Order可以理解爲關係型數據庫中的Order；Order的構造函數Direction和property參數代表按照哪個字段進行升序還是降序。

現在按照id進行降序排序：

 @Test
    public void testPageAndSort() {

        Sort.Order order = new Sort.Order(Sort.Direction.DESC, "id");
        Sort sort = new Sort(order);

        Pageable pageable = new PageRequest(0, 5, sort);
        Page<Employee> page = employeePagingAndSortingRepository.findAll(pageable);

        System.out.println("查詢的總頁數："+ page.getTotalPages());
        System.out.println("總記錄數："+ page.getTotalElements());
        System.out.println("當前第幾頁：" + page.getNumber() + 1);
        System.out.println("當前頁面對象的集合："+ page.getContent());
        System.out.println("當前頁面的記錄數："+ page.getNumberOfElements());
    }

JpaRepository接口

• 創建接口繼承JpaRepository

package com.xx.repository;


import com.xx.domain.Employee;
import org.springframework.data.jpa.repository.JpaRepository;

public interface EmployeeJpaRepository extends JpaRepository<Employee,Integer>{
}

• 測試類：

package com.xx.repository;

import com.xx.domain.Employee;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;


@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration({"classpath:beans-new.xml"})
public class EmployeeJpaRepositoryTest {

    @Autowired
    private EmployeeJpaRepository employeeJpaRepository;

    @Test
    public void testFind() {
        Employee employee = employeeJpaRepository.findOne(99);
        System.out.println(employee);
    }
}

查看員工是否存在

@Test
    public void testExists() {
        Boolean result1 = employeeJpaRepository.exists(25);
        Boolean result2 = employeeJpaRepository.exists(130);
        System.out.println("Employee-25: " + result1);
        System.out.println("Employee-130: " + result2);
    }

JpaSpecificationExecutor接口

• Specification封裝了JPA Criteria查詢條件

• 沒有繼承其他接口。

  自定義接口

  這裏要尤爲注意，爲什麼我除了繼承JpaSpecificationExecutor還要繼承JpaRepository，就像前面說的，JpaSpecificationExecutor沒有繼承任何接口，如果我不繼承JpaRepository，那也就意味着不能繼承Repository接口，spring就不能進行管理，後面的自定義接口注入就無法完成。

package com.xx.repository;


import com.xx.domain.Employee;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.JpaSpecificationExecutor;


public interface EmployeeJpaSpecificationExecutor extends JpaSpecificationExecutor<Employee>,JpaRepository<Employee,Integer> {
}

測試類

測試結果包含分頁，降序排序，查詢條件爲年齡大於50

package com.xx.repository;

import com.xx.domain.Employee;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.domain.Page;
import org.springframework.data.domain.PageRequest;
import org.springframework.data.domain.Pageable;
import org.springframework.data.domain.Sort;
import org.springframework.data.jpa.domain.Specification;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;

import javax.persistence.criteria.*;


@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration({"classpath:beans-new.xml"})
public class EmployeeJpaSpecificationExecutorTest {

    @Autowired
    private EmployeeJpaSpecificationExecutor employeeJpaSpecificationExecutor;

    /**
     * 分頁
     * 排序
     * 查詢條件: age > 50
     */
    @Test
    public void testQuery() {

        Sort.Order order = new Sort.Order(Sort.Direction.DESC, "id");
        Sort sort = new Sort(order);

        Pageable pageable = new PageRequest(0, 5, sort);

        /**
         * root:查詢的類型（Employee）
         * query：添加查詢條件
         * cb:構建Predicate
         */
        Specification<Employee> specification = new Specification<Employee>() {
            @Override
            public Predicate toPredicate(Root<Employee> root, CriteriaQuery<?> query, CriteriaBuilder cb) {
                Path path = root.get("age");
                return cb.gt(path, 50);
            }
        };

        Page<Employee> page = employeeJpaSpecificationExecutor.findAll(specification, pageable);

        System.out.println("查詢的總頁數："+ page.getTotalPages());
        System.out.println("總記錄數："+ page.getTotalElements());
        System.out.println("當前第幾頁：" + page.getNumber() + 1);
        System.out.println("當前頁面對象的集合："+ page.getContent());
        System.out.println("當前頁面的記錄數："+ page.getNumberOfElements());

    }

}