Spring Data JPA(day03)

1.有时我们在查询某个实体的时候，给定的条件是不固定的，这时就需要动态构建相应的查询语句，
在 Spring Data JPA 中可以通过 JpaSpecificationExecutor 接口查询。相比 JPQL,其优势是类型安全,更加
的面向对象。

import java.util.List;
import org.springframework.data.domain.Page;
import org.springframework.data.domain.Pageable;
import org.springframework.data.domain.Sort;
import org.springframework.data.jpa.domain.Specification;
/**
* JpaSpecificationExecutor中定义的方法
**/
public interface JpaSpecificationExecutor<T> {
//根据条件查询一个对象
T findOne(Specification<T> spec);
//根据条件查询集合
List<T> findAll(Specification<T> spec);
//根据条件分页查询
Page<T> findAll(Specification<T> spec, Pageable pageable);
//排序查询查询
List<T> findAll(Specification<T> spec, Sort sort);
//统计查询
long count(Specification<T> spec);
}

对于 JpaSpecificationExecutor，这个接口基本是围绕着 Specification 接口来定义的。我们可以简单的
理解为，Specification 构造的就是查询条件。
Specification 接口中只定义了如下一个方法：
//构造查询条件

/**
* root ：Root接口，代表查询的根对象，可以通过root获取实体中的属性
* query ：代表一个顶层查询对象，用来自定义查询
* cb ：用来构建查询，此对象里有很多条件方法
**/
public Predicate toPredicate(Root<T> root, CriteriaQuery<?> query, CriteriaBuilder
cb);

**1.1接下来使用 Specifications完成条件查询 **

1. 先创建maven,不使用·骨架·（一路next）
   
   具体目录如图
   2.导入pom.xml的依赖

<properties>
        <spring.version>4.2.4.RELEASE</spring.version>
        <hibernate.version>5.0.7.Final</hibernate.version>
        <slf4j.version>1.6.6</slf4j.version>
        <log4j.version>1.2.12</log4j.version>
        <c3p0.version>0.9.1.2</c3p0.version>
        <mysql.version>5.1.6</mysql.version>
    </properties>
    <dependencies>
        <!-- junit单元测试 -->
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.9</version>
            <scope>test</scope>
        </dependency>
        <!-- spring beg -->
        <dependency>
            <groupId>org.aspectj</groupId>
            <artifactId>aspectjweaver</artifactId>
            <version>1.6.8</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-aop</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context-support</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-orm</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-beans</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-core</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <!-- spring end -->

        <!-- hibernate beg -->
        <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-core</artifactId>
            <version>${hibernate.version}</version>
        </dependency>
        <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-entitymanager</artifactId>
            <version>${hibernate.version}</version>
        </dependency>
        <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-validator</artifactId>
            <version>5.2.1.Final</version>
        </dependency>
        <!-- hibernate end -->

        <!-- c3p0 beg -->
        <dependency>
            <groupId>c3p0</groupId>
            <artifactId>c3p0</artifactId>
            <version>${c3p0.version}</version>
        </dependency>
        <!-- c3p0 end -->

        <!-- log end -->
        <dependency>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
            <version>${log4j.version}</version>
        </dependency>
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-api</artifactId>
            <version>${slf4j.version}</version>
        </dependency>
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-log4j12</artifactId>
            <version>${slf4j.version}</version>
        </dependency>
        <!-- log end -->


        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>${mysql.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.data</groupId>
            <artifactId>spring-data-jpa</artifactId>
            <version>1.9.0.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-test</artifactId>
            <version>4.2.4.RELEASE</version>
        </dependency>

        <!-- el beg 使用spring data jpa 必须引入 -->
        <dependency>
            <groupId>javax.el</groupId>
            <artifactId>javax.el-api</artifactId>
            <version>2.2.4</version>
        </dependency>

        <dependency>
            <groupId>org.glassfish.web</groupId>
            <artifactId>javax.el</artifactId>
            <version>2.2.4</version>
        </dependency>
        <!-- el end -->
        <dependency>
            <groupId>javax.xml.bind</groupId>
            <artifactId>jaxb-api</artifactId>
            <version>2.3.0</version>
        </dependency>
        <dependency>
            <groupId>com.sun.xml.bind</groupId>
            <artifactId>jaxb-impl</artifactId>
            <version>2.3.0</version>
        </dependency>
        <dependency>
            <groupId>com.sun.xml.bind</groupId>
            <artifactId>jaxb-core</artifactId>
            <version>2.3.0</version>
        </dependency>
        <dependency>
            <groupId>javax.activation</groupId>
            <artifactId>activation</artifactId>
            <version>1.1.1</version>
        </dependency>
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>fastjson</artifactId>
            <version>1.2.41</version>
        </dependency>
    </dependencies>
    <build>
        <plugins>
            <plugin>
                <artifactId>maven-compiler-plugin</artifactId>
                <configuration>
                    <source>11</source>
                    <target>11</target>
                </configuration>
            </plugin>
        </plugins>
    </build>

3.创建入下图响应的目录结构
3.1CustomerDao的源代码：

package itcast.dao;

import itcast.entity.Customer;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.JpaSpecificationExecutor;
import org.springframework.data.jpa.repository.Modifying;
import org.springframework.data.jpa.repository.Query;

import java.lang.annotation.Native;
import java.util.List;

public interface CustomerDao extends JpaRepository<Customer,Long>, JpaSpecificationExecutor<Customer> {

}

3.2Customer源代码：

package itcast.entity;

import javax.persistence.*;
import java.io.Serializable;

@Entity//声明实体类
@Table(name = "cst_customer")//建立实体类和表的映射关系
public class Customer implements Serializable {
    //声明当前私有属性为主键
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY) //配置主键的生成策略
    //指定和表中 cust_id 字段的映射关系
    @Column(name = "cust_id")
    private Long custId;
    @Column(name="cust_name") //指定和表中 cust_name 字段的映射关系
    private String custName;
    @Column(name="cust_source")//指定和表中 cust_source 字段的映射关系
    private String custSource;
    @Column(name="cust_industry")//指定和表中 cust_industry 字段的映射关系
    private String custIndustry;
    @Column(name="cust_level")//指定和表中 cust_level 字段的映射关系
    private String custLevel;
    @Column(name="cust_address")//指定和表中 cust_address 字段的映射关系
    private String custAddress;
    @Column(name="cust_phone")//指定和表中 cust_phone 字段的映射关系
    private String custPhone;

    public Long getCustId() {
        return custId;
    }

    public void setCustId(Long custId) {
        this.custId = custId;
    }

    public String getCustName() {
        return custName;
    }

    public void setCustName(String custName) {
        this.custName = custName;
    }

    public String getCustSource() {
        return custSource;
    }

    public void setCustSource(String custSource) {
        this.custSource = custSource;
    }

    public String getCustIndustry() {
        return custIndustry;
    }

    public void setCustIndustry(String custIndustry) {
        this.custIndustry = custIndustry;
    }

    public String getCustLevel() {
        return custLevel;
    }

    public void setCustLevel(String custLevel) {
        this.custLevel = custLevel;
    }

    public String getCustAddress() {
        return custAddress;
    }

    public void setCustAddress(String custAddress) {
        this.custAddress = custAddress;
    }

    public String getCustPhone() {
        return custPhone;
    }

    public void setCustPhone(String custPhone) {
        this.custPhone = custPhone;
    }

    @Override
    public String toString() {
        return "Customer{" +
                "custId=" + custId +
                ", custName='" + custName + '\'' +
                ", custSource='" + custSource + '\'' +
                ", custIndustry='" + custIndustry + '\'' +
                ", custLevel='" + custLevel + '\'' +
                ", custAddress='" + custAddress + '\'' +
                ", custPhone='" + custPhone + '\'' +
                '}';
    }
}

3.3配置文件applicationContex.xml的代码：

<?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:aop="http://www.springframework.org/schema/aop"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:jdbc="http://www.springframework.org/schema/jdbc" xmlns:tx="http://www.springframework.org/schema/tx"
       xmlns:jpa="http://www.springframework.org/schema/data/jpa" xmlns:task="http://www.springframework.org/schema/task"
       xsi:schemaLocation="
		http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
		http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop.xsd
		http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd
		http://www.springframework.org/schema/jdbc http://www.springframework.org/schema/jdbc/spring-jdbc.xsd
		http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsd
		http://www.springframework.org/schema/data/jpa
		http://www.springframework.org/schema/data/jpa/spring-jpa.xsd">

    <!-- 1.dataSource 配置数据库连接池-->
    <bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource">
        <property name="driverClass" value="com.mysql.jdbc.Driver" />
        <property name="jdbcUrl" value="jdbc:mysql://localhost:3306/jpa" />
        <property name="user" value="root" />
        <property name="password" value="xxxxx" />
    </bean>

    <!-- 2.配置entityManagerFactory -->
    <bean id="entityManagerFactory" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
        <property name="dataSource" ref="dataSource" />
        <property name="packagesToScan" value="itcast.entity" />
        <property name="persistenceProvider">
            <bean class="org.hibernate.jpa.HibernatePersistenceProvider" />
        </property>
        <!--JPA的供应商适配器-->
        <property name="jpaVendorAdapter">
            <bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter">
                <property name="generateDdl" value="false" />
                <property name="database" value="MYSQL" />
                <property name="databasePlatform" value="org.hibernate.dialect.MySQLDialect" />
                <property name="showSql" value="true" />
            </bean>
        </property>
        <property name="jpaDialect">
            <bean class="org.springframework.orm.jpa.vendor.HibernateJpaDialect" />
        </property>
    </bean>


    <!-- 3.事务管理器-->
    <!-- JPA事务管理器  -->
    <bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager">
        <property name="entityManagerFactory" ref="entityManagerFactory" />
    </bean>

    <!-- 整合spring data jpa-->
    <jpa:repositories base-package="itcast.dao"
                      transaction-manager-ref="transactionManager"
                      entity-manager-factory-ref="entityManagerFactory"></jpa:repositories>

    <!-- 4.txAdvice-->
    <tx:advice id="txAdvice" transaction-manager="transactionManager">
        <tx:attributes>
            <tx:method name="save*" propagation="REQUIRED"/>
            <tx:method name="insert*" propagation="REQUIRED"/>
            <tx:method name="update*" propagation="REQUIRED"/>
            <tx:method name="delete*" propagation="REQUIRED"/>
            <tx:method name="get*" read-only="true"/>
            <tx:method name="find*" read-only="true"/>
            <tx:method name="*" propagation="REQUIRED"/>
        </tx:attributes>
    </tx:advice>

    <!-- 5.aop-->
    <aop:config>
        <aop:pointcut id="pointcut" expression="execution(* cn.itcast.service.*.*(..))" />
        <aop:advisor advice-ref="txAdvice" pointcut-ref="pointcut" />
    </aop:config>

    <context:component-scan base-package="itcast"></context:component-scan>

    <!--组装其它 配置文件-->

</beans>

接下来我们开始进入基于 Specifications的查询方式

package testSpecifications;

import itcast.dao.CustomerDao;
import itcast.entity.Customer;
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.*;
import java.util.List;

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations = "classpath:applicationContex.xml")//加载配置文件
public class testDemo {
    //依赖注入customerDao
    @Autowired
    private CustomerDao customerDao;

    /**
     * 查询一个数据
     */
    @Test
    public void testSpecifications() {
        //使用匿名内部类的方式，创建一个Specification的实现类，并实现toPredicate方法
        Specification<Customer> specification = new Specification<Customer>() {
            @Override
            public Predicate toPredicate(Root<Customer> root, CriteriaQuery<?> criteriaQuery, CriteriaBuilder criteriaBuilder) {
                return criteriaBuilder.equal(root.get("custName"),"大");//进行精准匹配
            }
        };
        Customer one = customerDao.findOne(specification);
        System.out.println(one);
    }
}

运行结果：
一下是其他方法的代码：

/**
     * 模糊查询
     * equal()：直接得到path对象(属性),然后进行比较即可
     * gt(),lt(),ge().le(),like(),得到path对象，根据path指定比较的参数类型，再去进行比较
     *      指定参数类型:path.as()
     */
    @Test
    public void testSpecifications01(){
        //使用匿名内部类的方式，创建一个Specification的实现类，并实现toPredicate方法
        Specification<Customer> specification = new Specification<Customer>() {
            @Override
            public Predicate toPredicate(Root<Customer> root, CriteriaQuery<?> criteriaQuery, CriteriaBuilder criteriaBuilder) {
                return criteriaBuilder.like(root.get("custAddress").as(String.class),"%上%");
            }
        };
//        List<Customer> two = (List<Customer>) customerDao.findAll(specification);
//        for(Customer c:two){
//            System.out.println(c);
//        }
        //添加排序
        //创建排序，需要调用构造方法实例化sour对象
        //第一个参数：排序的规则,顺序还是倒叙或者其他
        //Sort.Direction.DESC倒叙
        //第二个参数：排序的属性名
        Sort sort = new Sort(Sort.Direction.DESC,"custId");
        List<Customer> all = customerDao.findAll(specification, sort);
        for(Customer c:all){
           System.out.println(c);
        }

    }

    /**
     * 多条件查询
     */
    @Test
    public void testSpecifications02(){
        //使用匿名内部类的方式，创建一个Specification的实现类，并实现toPredicate方法
        Specification<Customer> specification = new Specification<Customer>() {
            @Override
            public Predicate toPredicate(Root<Customer> root, CriteriaQuery<?> criteriaQuery, CriteriaBuilder criteriaBuilder) {
                Path<Object> custAddress = root.get("custAddress");
                Predicate predicate = criteriaBuilder.equal(custAddress, "上海广东");
                Path<Object> custName = root.get("custName");
                Predicate predicate1 = criteriaBuilder.equal(custName, "11");
               // criteriaBuilder.or()或的形式查询，其中一个条件符合就可以
                Predicate or = criteriaBuilder.or(predicate, predicate1);
                Predicate and = criteriaBuilder.and(predicate, predicate1);
                return or;//将多个查询条件组合在一起，与，只有两个条件符合就通过
            }
        };
        List<Customer> two = (List<Customer>) customerDao.findAll(specification);
        for(Customer c:two){
            System.out.println(c);
        }
    }

    /**
     * 分页查询
     */
    @Test
    public void testPage() {
        Specification<Customer> specification = new Specification<Customer>() {
            @Override
            public Predicate toPredicate(Root<Customer> root, CriteriaQuery<?> criteriaQuery, CriteriaBuilder criteriaBuilder) {
                return null;
            }
        };
        /**
         * 构造分页参数
         * Pageable : 接口
         * PageRequest实现了Pageable接口，调用构造方法的形式构造
         * 第一个参数：页码（从0开始）
         * 第二个参数：每页查询条数
         */
        Pageable pageable = new PageRequest(0,2);
        /**
         * 分页查询，封装为Spring Data Jpa 内部的page bean
         * 此重载的findAll方法为分页方法需要两个参数
         * 第一个参数：查询条件Specification
         * 第二个参数：分页参数
         */
        Page<Customer> all = customerDao.findAll(specification, pageable);
        for ( Customer c: all){
            System.out.println(c);
        }
        System.out.println(all.getContent());//得到数据集合列表
        System.out.println(all.getTotalPages());//得到总页数
        System.out.println(all.getTotalElements());//得到总条数
        }