SpringData----Spring Data JPA（上）

Spring Data JPA：Spring Data JPA 是 spring data 項目下的一個模塊。提供了一套基於 JPA標準操作數據庫的簡化方案。底層默認的是依賴 Hibernate JPA 來實現的。
Spring Data JPA 的技術特點：我們只需要定義接口並集成 Spring Data JPA 中所提供的接口就可以了。不需要編寫接口實現類。

一、創建 Spring

1 導入 jar 包

2 修改配置文件

<jpa:repositories base-package="com.bjsxt.dao"/>

<?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:aop="http://www.springframework.org/schema/aop" 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/context
	http://www.springframework.org/schema/context/spring-context.xsd
	http://www.springframework.org/schema/aop
	http://www.springframework.org/schema/aop/spring-aop.xsd
	http://www.springframework.org/schema/data/jpa 
	http://www.springframework.org/schema/data/jpa/spring-jpa.xsd
	http://www.springframework.org/schema/tx 
	http://www.springframework.org/schema/tx/spring-tx.xsd">
	<!-- 配置讀取properties文件的工具類 -->
	<context:property-placeholder location="classpath:jdbc.properties"/>
	
	<!-- 配置c3p0數據庫連接池 -->
	<bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource">
		<property name="jdbcUrl" value="${jdbc.url}"/>
		<property name="driverClass" value="${jdbc.driver.class}"/>
		<property name="user" value="${jdbc.username}"/>
		<property name="password" value="${jdbc.password}"/>
	</bean>
	
	<!-- Spring整合JPA  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">
				<!-- hibernate相關的屬性的注入 -->
				<!-- 配置數據庫類型 -->
				<property name="database" value="MYSQL"/>
				<!-- 正向工程 自動創建表 -->
				<property name="generateDdl" value="true"/>
				<!-- 顯示執行的SQL -->
				<property name="showSql" value="true"/>
			</bean>
		</property>
		<!-- 掃描實體的包 -->
		<property name="packagesToScan">
			<list>
				<value>com.bjsxt.pojo</value>
			</list>
		</property>
	</bean>

	<!-- 配置Hibernate的事務管理器 -->
	<bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager">
		<property name="entityManagerFactory" ref="entityManagerFactory"/>
	</bean>
	
	<!-- 配置開啓註解事務處理 -->
	<tx:annotation-driven transaction-manager="transactionManager"/>
	
	<!-- 配置springIOC的註解掃描 -->
	<context:component-scan base-package="com.bjsxt"/>
	
	<!-- Spring Data JPA 的配置 -->
	<!-- base-package：掃描dao接口所在的包 -->
	<jpa:repositories base-package="com.bjsxt.dao"/>
</beans>

3 編寫 Dao

public interface UsersDao extends JpaRepository<Users, Integer> {
}

4 編寫測試代碼

package com.bjsxt.test;

import java.util.List;

import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.test.annotation.Rollback;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
import org.springframework.transaction.annotation.Transactional;

import com.bjsxt.dao.UsersDao;
import com.bjsxt.pojo.Users;

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration("classpath:applicationContext.xml")
public class UsersDaoImplTest {

	@Autowired
	private UsersDao usersDao;
	
	
	/**
	 * 添加用戶
	 */
	@Test
	@Transactional// 在測試類對於事務提交方式默認的是回滾。
	@Rollback(false)//取消自動回滾
	public void testInsertUsers(){
		Users users = new Users();
		users.setUserage(24);
		users.setUsername("張三");
		this.usersDao.save(users);
	}
	
}

二、 Spring Data JPA 的接口繼承結構

三、 Spring Data JPA 的運行原理

@PersistenceContext(name="entityManagerFactory")
private EntityManager em;
@Test
public void test1(){
    //org.springframework.data.jpa.repository.support.SimpleJpaRepository@fba8bf
    //System.out.println(this.usersDao);
    //class com.sun.proxy.$Proxy29 代理對象 是基於 JDK 的動態代理方式創建的
    //System.out.println(this.usersDao.getClass());
    JpaRepositoryFactory factory = new JpaRepositoryFactory(em);
    //getRepository(UsersDao.class);可以幫助我們爲接口生成實現類。而這個實現類是 SimpleJpaRepository 的對象
    //要求：該接口必須要是繼承 Repository 接口
    UsersDao ud = factory.getRepository(UsersDao.class);
    System.out.println(ud);
    System.out.println(ud.getClass());
}

四、 Repository 接口

Repository 接口是 Spring Data JPA 中爲我我們提供的所有接口中的頂層接口
Repository 提供了兩種查詢方式的支持
1）基於方法名稱命名規則查詢
2）基於@Query 註解查詢

1.1創建接口

package com.bjsxt.dao;


import java.util.List;

import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.repository.Repository;

import com.bjsxt.pojo.Users;

/**
 * Repository接口講解
 * @author Administrator
 *
 */
public interface UsersDao extends Repository<Users, Integer> {
	
	List<Users> findByUsernameIs(String string);
	List<Users> findByUsernameLike(String string);
	List<Users> findByUsernameAndUserageGreaterThanEqual(String name,Integer age);
}

1.2測試類

package com.bjsxt.test;

import java.util.List;

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 com.bjsxt.dao.UsersDao;
import com.bjsxt.pojo.Users;

/**
 * Repository接口測試
 * @author Administrator
 *
 */
@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration("classpath:applicationContext.xml")
public class RepositoryTest {

	@Autowired
	private UsersDao usersDao;
	
	/**
	 * 需求：使用用戶名作爲查詢條件
	 */
	@Test
	public void test1(){
		/**
		 * 判斷相等的條件，有三種表示方式
		 * 1,什麼都不寫，默認的就是做相等判斷
		 * 2,Is
		 * 3,Equal
		 */
		List<Users> list = this.usersDao.findByUsernameIs("王五");
		for (Users users : list) {
			System.out.println(users);
		}
	}
	
	/**
	 * 需求：根據用戶姓名做Like處理
	 * Like:條件關鍵字
	 */
	@Test
	public void test2(){
		List<Users> list = this.usersDao.findByUsernameLike("王%");
		for (Users users : list) {
			System.out.println(users);
		}
	}
	
	/**
	 * 需求：查詢名稱爲王五，並且他的年齡大於等於22歲
	 */
	@Test
	public void test3(){
		List<Users> list = this.usersDao.findByUsernameAndUserageGreaterThanEqual("王五", 22);
		for (Users users : list) {
			System.out.println(users);
		}
	}
}

2 基於@Query 註解的查詢

2.1通過 JPQL 語句查詢

JPQL：通過 Hibernate 的 HQL 演變過來的。他和 HQL 語法及其相似。

2.1.1創建接口

package com.bjsxt.dao;


import java.util.List;

import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.Query;
import org.springframework.data.repository.Repository;

import com.bjsxt.pojo.Users;

/**
 * Repository接口講解
 * @author Administrator
 *
 */
public interface UsersDao extends Repository<Users, Integer> {
	//方法名稱命名規則
	List<Users> findByUsernameIs(String string);
	List<Users> findByUsernameLike(String string);
	List<Users> findByUsernameAndUserageGreaterThanEqual(String name,Integer age);
	
	//使用@Query註解查詢
	@Query(value="from Users where username = ?")
	List<Users> queryUserByNameUseJPQL(String name);
	
	@Query("from Users where username like ?")
	List<Users> queryUserByLikeNameUseJPQL(String name);
	
	@Query("from Users where username = ? and userage >= ?")
	List<Users> queryUserByNameAndAge(String name,Integer age);
}

2.1.2測試類

package com.bjsxt.test;

import java.util.List;

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 com.bjsxt.dao.UsersDao;
import com.bjsxt.pojo.Users;

/**
 * Repository接口測試
 * @author Administrator
 *
 */
@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration("classpath:applicationContext.xml")
public class RepositoryTest {

	@Autowired
	private UsersDao usersDao;
	
	
	/**
	 * 測試@Query查詢 JPQL
	 */
	@Test
	public void test4(){
		List<Users> list = this.usersDao.queryUserByNameUseJPQL("王五");
		for (Users users : list) {
			System.out.println(users);
		}
	}
	
	/**
	 * 測試@Query查詢 JPQL
	 */
	@Test
	public void test5(){
		List<Users> list = this.usersDao.queryUserByLikeNameUseJPQL("王%");
		for (Users users : list) {
			System.out.println(users);
		}
	}
	
	/**
	 * 測試@Query查詢 JPQL
	 */
	@Test
	public void test6(){
		List<Users> list = this.usersDao.queryUserByNameAndAge("王五", 22);
		for (Users users : list) {
			System.out.println(users);
		}
	}
	
}

2.2通過 SQL 語句查詢

2.2.1創建接口

nativeQuery:默認的是 false.表示不開啓 sql 查詢。是否對 value 中的語句做轉義。

nativeQuery=true

	//使用@Query註解查詢SQL
	//nativeQuery:默認的是false.表示不開啓sql查詢。是否對value中的語句做轉義。
	@Query(value="select * from t_users where username = ?",nativeQuery=true)
	List<Users> queryUserByNameUseSQL(String name);

	@Query(value="select * from t_users where username like ?",nativeQuery=true)
	List<Users> queryUserByLikeNameUseSQL(String name);
	
	@Query(value="select * from t_users where username = ? and userage >= ?",nativeQuery=true)
	List<Users> queryUserByNameAndAgeUseSQL(String name,Integer age);

2.2.2測試類

	/**
	 * 測試@Query查詢 SQL
	 */
	@Test
	public void test7(){
		List<Users> list = this.usersDao.queryUserByNameUseSQL("王五");
		for (Users users : list) {
			System.out.println(users);
		}
	}
	
	/**
	 * 測試@Query查詢 SQL
	 */
	@Test
	public void test8(){
		List<Users> list = this.usersDao.queryUserByLikeNameUseSQL("王%");
		for (Users users : list) {
			System.out.println(users);
		}
	}
	
	/**
	 * 測試@Query查詢 SQL
	 */
	@Test
	public void test9(){
		List<Users> list = this.usersDao.queryUserByNameAndAgeUseSQL("王五", 22);
		for (Users users : list) {
			System.out.println(users);
		}
	}

3 通過@Query 註解完成數據更新

3.1創建接口

@Query("update Users set userage = ? where userid = ?")
@Modifying //@Modifying 當前語句是一個更新語句
void updateUserAgeById(Integer age,Integer id);

3.2測試類

/**
* 測試@Query update
*/
@Test
@Transactional
@Rollback(false)
public void test10(){
    this.usersDao.updateUserAgeById(24, 5);
}

五、 CrudRepository 接口

1 創建接口

package com.bjsxt.dao;



import org.springframework.data.repository.CrudRepository;

import com.bjsxt.pojo.Users;

/**
 * CrudRepository接口講解
 * @author Administrator
 *
 */
public interface UsersDao extends CrudRepository<Users, Integer> {
	
}

2 測試代碼

package com.bjsxt.test;

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

import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.test.annotation.Rollback;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
import org.springframework.transaction.annotation.Transactional;

import com.bjsxt.dao.UsersDao;
import com.bjsxt.pojo.Users;

/**
 * CrudRepository接口測試
 * @author Administrator
 *
 */
@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration("classpath:applicationContext.xml")
public class RepositoryTest {

	@Autowired
	private UsersDao usersDao;
	
	/**
	 * 添加單條數據
	 */
	@Test
	public void test1(){
		Users user = new Users();
		user.setUserage(21);
		user.setUsername("趙小麗");
		this.usersDao.save(user);
	}
	
	/**
	 * 批量添加數據
	 */
	@Test
	public void test2(){
		Users user = new Users();
		user.setUserage(21);
		user.setUsername("趙小麗");
		
		Users user1 = new Users();
		user1.setUserage(25);
		user1.setUsername("王小虎");
		
		List<Users> list= new ArrayList<>();
		list.add(user);
		list.add(user1);
		
		this.usersDao.save(list);
		
	}
	
	/**
	 * 根據ID查詢單條數據
	 */
	@Test
	public void test3(){
		Users users = this.usersDao.findOne(13);
		System.out.println(users);
	}
	
	/**
	 * 查詢全部數據
	 */
	@Test
	public void test4(){
		List<Users> list = (List<Users>)this.usersDao.findAll();
		for (Users users : list) {
			System.out.println(users);
		}
	}
	
	/**
	 * 刪除數據
	 */
	@Test
	public void test5(){
		this.usersDao.delete(13);
	}
	
	/**
	 * 更新數據 方式一
	 */
	@Test
	public void test6(){
		Users user = this.usersDao.findOne(12);
		user.setUsername("王小紅");
		this.usersDao.save(user);
	}
	
	/**
	 * 更新數據 方式二
	 */
	@Test
	@Transactional
	@Rollback(false)
	public void test7(){
		Users user = this.usersDao.findOne(12);//持久化狀態的
		user.setUsername("王小小");
	}
}

六、 PagingAndSortingRepository 接口

1 分頁處理

1.1創建接口

package com.bjsxt.dao;



import org.springframework.data.repository.CrudRepository;
import org.springframework.data.repository.PagingAndSortingRepository;

import com.bjsxt.pojo.Users;

/**
 * PagingAndSortingRepository接口講解
 * @author Administrator
 *
 */
public interface UsersDao extends PagingAndSortingRepository<Users, Integer>{
	
}

1.2測試代碼

package com.bjsxt.test;

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

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.annotation.Rollback;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
import org.springframework.transaction.annotation.Transactional;

import com.bjsxt.dao.UsersDao;
import com.bjsxt.pojo.Users;

/**
 * CrudRepository接口測試
 * @author Administrator
 *
 */
@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration("classpath:applicationContext.xml")
public class RepositoryTest {

	@Autowired
	private UsersDao usersDao;
	
	/**
	 * 分頁
	 */
	@Test
	public void test1(){
		int page = 2; //page:當前頁的索引。注意索引都是從0開始的。
		int size = 3;// size:每頁顯示3條數據
		Pageable pageable= new PageRequest(page, size);
		Page<Users> p = this.usersDao.findAll(pageable);
		System.out.println("數據的總條數："+p.getTotalElements());
		System.out.println("總頁數："+p.getTotalPages());
		List<Users> list = p.getContent();
		for (Users users : list) {
			System.out.println(users);
		}
	}
}

2 排序的處理

2.1測試代碼

	/**
	 * 對單列做排序處理
	 */
	@Test
	public void test2(){
		//Sort:該對象封裝了排序規則以及指定的排序字段(對象的屬性來表示)
		//direction:排序規則
		//properties:指定做排序的屬性
		Sort sort = new Sort(Direction.DESC,"userid");
		List<Users> list = (List<Users>)this.usersDao.findAll(sort);
		for (Users users : list) {
			System.out.println(users);
		}
	}
	
	/**
	 * 多列的排序處理
	 */
	@Test
	public void test3(){
		//Sort:該對象封裝了排序規則以及指定的排序字段(對象的屬性來表示)
		//direction:排序規則
		//properties:指定做排序的屬性
		Order order1 = new Order(Direction.DESC,"userage");
		Order order2 = new Order(Direction.ASC,"username");
		Sort sort = new Sort(order1,order2);
		List<Users> list = (List<Users>)this.usersDao.findAll(sort);
		for (Users users : list) {
			System.out.println(users);
		}
	}

七、 JpaRepository 接口

JpaRepository 接口是我們開發時使用的最多的接口。其特點是可以幫助我們將其他接口的方法的返回值做適配處理。可以使得我們在開發時更方便的使用這些方法

package com.bjsxt.dao;



import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.repository.CrudRepository;
import org.springframework.data.repository.PagingAndSortingRepository;

import com.bjsxt.pojo.Users;

/**
 * JpaRepository接口講解
 * @author Administrator
 *
 */
public interface UsersDao extends JpaRepository<Users, Integer>{
	
}

2 測試代碼

package com.bjsxt.test;

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

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.domain.Sort.Direction;
import org.springframework.data.domain.Sort.Order;
import org.springframework.test.annotation.Rollback;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.TestPropertySource;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
import org.springframework.transaction.annotation.Transactional;

import com.bjsxt.dao.UsersDao;
import com.bjsxt.pojo.Users;

/**
 * JpaRepository接口測試
 * @author Administrator
 *
 */
@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration("classpath:applicationContext.xml")
public class RepositoryTest {

	@Autowired
	private UsersDao usersDao;
	
	/**
	 * 查詢全部數據
	 */
	@Test
	public void test1(){
		List<Users> list  = this.usersDao.findAll();
		for (Users users : list) {
			System.out.println(users);
		}
	}
}

八、 JpaSpecificationExecutor 接口--------完成多條件查詢，並且支持分頁與排序

注意：JpaSpecificationExecutor<Users>:不能單獨使用，需要配合着 jpa 中的其他接口一起使用

1 單條件查詢

1.1創建接口

import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.JpaSpecificationExecutor;
import org.springframework.data.repository.CrudRepository;
import org.springframework.data.repository.PagingAndSortingRepository;

import com.bjsxt.pojo.Users;

/**
 * JpaSpecificationExecutor接口講解
 * @author Administrator
 *注意：JpaSpecificationExecutor<Users>:不能單獨使用，需要配合着jpa中的其他接口一起使用
 */
public interface UsersDao extends JpaRepository<Users, Integer>,JpaSpecificationExecutor<Users>{
	
}

1.2測試代碼

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

import javax.persistence.criteria.CriteriaBuilder;
import javax.persistence.criteria.CriteriaQuery;
import javax.persistence.criteria.Predicate;
import javax.persistence.criteria.Root;

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.domain.Sort.Direction;
import org.springframework.data.domain.Sort.Order;
import org.springframework.data.jpa.domain.Specification;
import org.springframework.test.annotation.Rollback;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.TestPropertySource;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
import org.springframework.transaction.annotation.Transactional;

import com.bjsxt.dao.UsersDao;
import com.bjsxt.pojo.Users;

/**
 * JpaRepository接口測試
 * @author Administrator
 *
 */
@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration("classpath:applicationContext.xml")
public class RepositoryTest {

	@Autowired
	private UsersDao usersDao;
	
	/**
	 * 需求：根據用戶姓名查詢數據
	 */
	@Test
	public void test1(){
		Specification<Users> spec = new Specification<Users>() {

			/**
			 * @return Predicate:定義了查詢條件
			 * @param Root<Users> root:根對象。封裝了查詢條件的對象
			 * @param CriteriaQuery<?> query:定義了一個基本的查詢。一般不使用
			 * @param CriteriaBuilder cb:創建一個查詢條件
			 */
			@Override
			public Predicate toPredicate(Root<Users> root, CriteriaQuery<?> query, CriteriaBuilder cb) {
				Predicate pre = cb.equal(root.get("username"), "王五");
				return pre;
			}
		};
		List<Users> list = this.usersDao.findAll(spec);
		for (Users users : list) {
			System.out.println(users);
		}
	}
}

2 多條件查詢

2.1給定查詢條件方式一

	/**
	 * 多條件查詢 方式一
	 * 需求：使用用戶姓名以及年齡查詢數據
	 */
	@Test
	public void test2(){
		Specification<Users> spec = new Specification<Users>() {

			@Override
			public Predicate toPredicate(Root<Users> root, CriteriaQuery<?> query, CriteriaBuilder cb) {
				List<Predicate> list = new ArrayList<>();
				list.add(cb.equal(root.get("username"),"王五"));
				list.add(cb.equal(root.get("userage"),24));
				//此時條件之間是沒有任何關係的。
				Predicate[] arr = new Predicate[list.size()];
				return cb.and(list.toArray(arr));
			}
			
		};
		List<Users> list = this.usersDao.findAll(spec);
		for (Users users : list) {
			System.out.println(users);
		}
	}

2.2給定查詢條件方式二
cb.like(root.get("username").as(String.class),"王%");

/**
* 多條件查詢 方式二
* 需求：使用用戶姓名或者年齡查詢數據
*/
@Test
public void test3(){
Specification<Users> spec = new Specification<Users>() {
    @Override
    public Predicate toPredicate(Root<Users> root,CriteriaQuery<?> query, CriteriaBuilder cb) {
    return cb.or(cb.equal(root.get("username"),"王五"),cb.equal(root.get("userage"), 25));
    }
};
    List<Users> list = this.usersDao.findAll(spec);
    for (Users users : list) {
        System.out.println(users);
    }
}

3 分頁

	/**
	 * 需求：查詢王姓用戶，並且做分頁處理
	 */
	@Test
	public void test4(){
		//條件
		Specification<Users> spec = new Specification<Users>() {

			@Override
			public Predicate toPredicate(Root<Users> root, CriteriaQuery<?> query, CriteriaBuilder cb) {
				return cb.like(root.get("username").as(String.class), "王%");
			}
			
		};
		
		//分頁
		Pageable pageable = new PageRequest(2, 2);
		Page<Users> page = this.usersDao.findAll(spec, pageable);
		System.out.println("總條數："+page.getTotalElements());
		System.out.println("總頁數："+page.getTotalPages());
		List<Users> list = page.getContent();
		for (Users users : list) {
			System.out.println(users);
		}
	}

4 排序

	/**
	 * 需求：查詢數據庫中王姓的用戶，並且根據用戶id做倒序排序
	 */
	@Test
	public void test5(){
		//條件
		Specification<Users> spec = new Specification<Users>() {

			@Override
			public Predicate toPredicate(Root<Users> root, CriteriaQuery<?> query, CriteriaBuilder cb) {
				return cb.like(root.get("username").as(String.class), "王%");
			}
			
		};
		//排序
		Sort sort = new Sort(Direction.DESC,"userid");
		List<Users> list = this.usersDao.findAll(spec, sort);
		for (Users users : list) {
			System.out.println(users);
		}
	}

5 分頁與排序

/**
	 * 需求：查詢數據庫中王姓的用戶，做分頁處理，並且根據用戶id做倒序排序
	 */
	@Test
	public void test6(){
		//排序等定義
		Sort sort = new Sort(Direction.DESC,"userid");
		//分頁的定義
		Pageable pageable = new PageRequest(2,2, sort);
		
		//查詢條件
		Specification<Users> spec = new Specification<Users>() {

			@Override
			public Predicate toPredicate(Root<Users> root, CriteriaQuery<?> query, CriteriaBuilder cb) {
				return cb.like(root.get("username").as(String.class), "王%");
			}
			
		};
		Page<Users> page = this.usersDao.findAll(spec, pageable);
		System.out.println("總條數："+page.getTotalElements());
		System.out.println("總頁數："+page.getTotalPages());
		List<Users> list = page.getContent();
		for (Users users : list) {
			System.out.println(users);
		}
	}

九、用戶自定義 Repository 接口

1 創建接口

package com.bjsxt.dao;

import com.bjsxt.pojo.Users;

public interface UsersRepository {

	public Users findUserById(Integer userid);
}

2 使用接口

package com.bjsxt.dao;



import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.JpaSpecificationExecutor;
import org.springframework.data.repository.CrudRepository;
import org.springframework.data.repository.PagingAndSortingRepository;

import com.bjsxt.pojo.Users;

/**
 * 用戶自定義Repository接口講解
 * @author Administrator
 */
public interface UsersDao extends JpaRepository<Users, Integer>,JpaSpecificationExecutor<Users>,UsersRepository{
	
}

3 創建接口實現類

package com.bjsxt.dao;

import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;

import com.bjsxt.pojo.Users;

public class UsersDaoImpl implements UsersRepository {

	@PersistenceContext(name="entityManagerFactory")
	private EntityManager em;
	
	@Override
	public Users findUserById(Integer userid) {
		System.out.println("MyRepository......");
		return this.em.find(Users.class, userid);
	}

}

4 編寫測試代碼

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration("classpath:applicationContext.xml")
public class RepositoryTest {

	@Autowired
	private UsersDao usersDao;
	
	/**
	 * 需求：根據用戶ID查詢數據
	 */
	@Test
	public void test1(){
		Users users = this.usersDao.findUserById(5);
		System.out.println(users);
	}
}

SpringData----Spring Data JPA（上）

物理機開關機

Linux/CentOS系統Tomcat 7/8.5/9部署SSL證書，端口爲8443能夠訪問成功，換成443卻訪問失敗

SpringBoot----Spring Boot 定時任務

SpringData----Spring Data JPA（上）

SpringCloud----SpringCloud 入門

SpringBoot----SpringBoot 整合Spring Data JPA(一)

Mac下配置sublime實現LaTeX

https://yachay.unat.edu.pe/blog/index.php?comment_area=format_blog&comment_component=blog&comment_co

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