动态查询
1、Specifications动态查询
方法列表:
public interface JpaSpecificationExecutor<T> {
T findOne(Specification<T> spec); //查询单个对象
List<T> findAll(Specification<T> spec); //查询列表
//查询全部,分页
//pageable:分页参数
//返回值:分页pageBean(page:是springdatajpa提供的)
Page<T> findAll(Specification<T> spec, Pageable pageable);
//查询列表
//Sort:排序参数
List<T> findAll(Specification<T> spec, Sort sort);
long count(Specification<T> spec);//统计查询
}
-
Specfication:查询条件
自定义我们自己的Specification实现类
实现
//root:查询的跟对象(查询的任何属性都可以从跟对象中获取)
//CriteriaQuery:顶层查询对象,自定义查询方式(了解:一般不用)
//CriteriaBuilder:查询的构造器,封装了很多的查询条件
Predicate toPredicate(Root<T> root, CriteriaQuery<?> query, CriteriaBuilder cb);
2、搭建环境
导入坐标:
<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 aop-->
<dependency>
<groupId>org.aspectj</groupId>
<artifactId>aspectjweaver</artifactId>
<version>1.6.8</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-aop</artifactId>
<version>${spring.version}</version>
</dependency>
<!--spring ioc-->
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context-support</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-beans</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-core</artifactId>
<version>${spring.version}</version>
</dependency>
<!--spring对orm框架的支持包-->
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-orm</artifactId>
<version>${spring.version}</version>
</dependency>
<!-- hibernate核心包 -->
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-core</artifactId>
<version>${hibernate.version}</version>
</dependency>
<!--hibernate对jpa实现的包-->
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-entitymanager</artifactId>
<version>${hibernate.version}</version>
</dependency>
<!--hibernate的验证包-->
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-validator</artifactId>
<version>5.2.1.Final</version>
</dependency>
<!-- c3p0 -->
<dependency>
<groupId>c3p0</groupId>
<artifactId>c3p0</artifactId>
<version>${c3p0.version}</version>
</dependency>
<!-- log-->
<dependency>
<groupId>log4j</groupId>
<artifactId>log4j</artifactId>
<version>${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>
<!--数据库-->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>${mysql.version}</version>
</dependency>
<!--spring data jpa的坐标-->
<dependency>
<groupId>org.springframework.data</groupId>
<artifactId>spring-data-jpa</artifactId>
<version>1.9.0.RELEASE</version>
</dependency>
<!--spring提供单元测试的坐标-->
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-test</artifactId>
<version>${spring.version}</version>
</dependency>
<!-- el 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 -->
</dependencies>
编写配置文件:
<?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: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">
<!-- 创建entityManagerFactory对象交给spring容器管理 -->
<bean id="entityManagerFactory" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
<property name="dataSource" ref="dataSource" />
<!--配置的扫描的包(实体类所在的包)-->
<property name="packagesToScan" value="com.sddm.entity" />
<!-- jpa的实现厂家 -->
<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">
<!--是否自动创建数据库表-->
<property name="generateDdl" value="false" />
<!--指定数据库类型-->
<property name="database" value="MYSQL" />
<!-- 数据库方言 -->
<property name="databasePlatform" value="org.hibernate.dialect.MySQLDialect" />
<!-- 是否显示sql -->
<property name="showSql" value="true" />
</bean>
</property>
<!--jpa的方言:高级的特性-->
<property name="jpaDialect">
<bean class="org.springframework.orm.jpa.vendor.HibernateJpaDialect" />
</property>
</bean>
<!-- 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="root" />
</bean>
<!-- 整合spring data jpa-->
<jpa:repositories base-package="com.sddm.dao"
transaction-manager-ref="transactionManager"
entity-manager-factory-ref="entityManagerFactory"></jpa:repositories>
<!-- 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>
<!-- 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>
<!-- aop-->
<aop:config>
<aop:pointcut id="pointcut" expression="execution(* com.sddm.service.*.*(..))" />
<aop:advisor advice-ref="txAdvice" pointcut-ref="pointcut" />
</aop:config>
<context:component-scan base-package="com.sddm"></context:component-scan>
<!--组装其它 配置文件-->
</beans>
创建实体类:
@Entity
@Table(name = "cst_customer")
public class Customer {
@Id//声明当前私有属性为主键
@GeneratedValue(strategy= GenerationType.IDENTITY) //配置主键的生成策略
@Column(name="cust_id") //指定和表中cust_id字段的映射关系
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")
private String custSource;
@Column(name="cust_industry")
private String custIndustry;
@Column(name="cust_level")
private String custLevel;
@Column(name="cust_address")
private String custAddress;
@Column(name="cust_phone")
private String custPhone;
//省略get和set方法
}
创建dao对象:
扫描二维码关注公众号,回复:
12411818 查看本文章
public interface CustomerDao extends JpaRepository<Customer,Long>, JpaSpecificationExecutor<Customer> {
}
项目结构:
测试案例:
1、根据客户名称查询,查询客户名称为sddm的客户
/*
* 根据条件,查询单个对象
*
*/
@Test
public void testSpec(){
Specification<Customer> spec = new Specification<Customer>() {
//匿名内部类
/*
* 自定义查询条件
* 1.实现Specification接口(提供泛型:查询的对象类型)
* 2.实现toPredicate方法(构造查询条件)
* 3.需要借助方法参数中的两个参数(
* root:获取需要查询的对象属性
* CriteriaQuery:构造查询条件的,内部封装了很多的查询条件(模糊匹配,精准匹配)
* )
* 案例:根据客户名称查询,查询客户名称为sddm的客户
* 查询条件
* 1.查询方式
* cb对象
* 2.比较的属性名称
* root对象
* */
public Predicate toPredicate(Root<Customer> root, CriteriaQuery<?> query, CriteriaBuilder cb) {
//1、获取比较的属性
Path<Object> custName = root.get("custName");
//2、构造查询条件: select * from cst_customer where cust_name = 'sddm'
/*
* 第一个参数:需要比较的属性(path对象)
* 第二个参数:当前需要比较的取值
* */
Predicate predicate = cb.equal(custName,"sddm");//进行精准匹配 (比较的属性,比较的属性的取值)
return predicate;
}
};
Customer customer = customerDao.findOne(spec);
System.out.println(customer);
}
查看结果:
2、多条件查询:根据客户名称(sddm)和客户所属行业查询(福州)
/*
* 多条件查询
* 案例:根据客户名称(sddm)和客户所属行业查询(福州)
* */
@Test
public void testSpec1(){
/*
* root:获取属性
* 客户名
* 所属行业
* cb:构造查询
* 1.构造客户名的精准匹配查询
* 2.构造所属行业的精准匹配查询
* 3.将以上两个查询联系起来
* */
Specification<Customer> spec = new Specification<Customer>() {
public Predicate toPredicate(Root<Customer> root, CriteriaQuery<?> query, CriteriaBuilder cb) {
Path<Object> custName = root.get("custName");//客户名
Path<Object> custIndustry = root.get("custIndustry");//所属行业
//构造查询
//1.构造客户名的精准匹配查询
Predicate p1 = cb.equal(custName, "sddm");//第一个参数,path(属性),第二个参数,属性的取值
//2.构造所属行业的精准匹配
Predicate p2 = cb.equal(custIndustry, "福州");//第一个参数,path(属性),第二个参数,属性的取值
//3.将多个查询条件组合到一起:组合(满足条件一并且满足条件二即可:与关系;满足条件一或满足条件二即可:或关系)
Predicate and = cb.and(p1, p2);//以与的形式拼接多个查询条件
//cb.or();//以或的形式拼接多个查询条件
return and;
}
};
Customer customer = customerDao.findOne(spec);
System.out.println(customer);
}
查看结果:
3、根据客户名称的模糊匹配,返回客户列表:
/*
* 案例:完成根据客户名称的模糊匹配,返回客户列表
* 客户名称以‘sddm’开头的
*
* 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.ad(类型的字节码对象)
* */
@Test
public void testSpec3(){
//构造查询条件
Specification<Customer> spec = new Specification<Customer>() {
public Predicate toPredicate(Root<Customer> root, CriteriaQuery<?> query, CriteriaBuilder cb) {
//查询属性:客户名
Path<Object> custName = root.get("custName");
//查询方式:模糊匹配
Predicate predicate = cb.like(custName.as(String.class), "sddm%");
return predicate;
}
};
List<Customer> customers = customerDao.findAll(spec);
for (Customer customer : customers){
System.out.println(customer);
}
}
查看結果:
4、排序:
@Test
public void testSpec3(){
//构造查询条件
Specification<Customer> spec = new Specification<Customer>() {
public Predicate toPredicate(Root<Customer> root, CriteriaQuery<?> query, CriteriaBuilder cb) {
//查询属性:客户名
Path<Object> custName = root.get("custName");
//查询方式:模糊匹配
Predicate predicate = cb.like(custName.as(String.class), "sddm%");
return predicate;
}
};
//添加排序
//创建排序对象,需要调用构造方法实例化sort对象
//第一个参数:排序的顺序(倒序,正序)
// Sort.Direction.DESC:倒序
// Sort.Direction.ASC:升序
//第二个参数:排序的属性名称
Sort sort = new Sort(Sort.Direction.DESC,"custId");
List<Customer> customers = customerDao.findAll(spec, sort);
for (Customer customer : customers){
System.out.println(customer);
}
}
查看結果:
5、分页查询:
/*
* 分页查询
* Specification:查询条件
* Pageable:分页参数
* 分页参数:查询的页码,每页查询的条数
* findAll(Specification,Pageable):带有条件的分页
* findAll(Pageable):没有条件的分页
* 返回:Page(springDataJpa为我们封装好的pageBean对象,能够为我们提供数据列表,总条数)
* */
@Test
public void testSpec4(){
Specification spec = null;
//Pagerequest对象是Pageable接口的实现类
/*
* 创建PageRequest的过程中,需要调用他的构造方法传入两个参数
* 第一个参数:当前查询的页数(从0开始)
* 第二个参数:每页查询的数量
* */
Pageable pageable = new PageRequest(0,2);
//分页查询
Page page = customerDao.findAll(spec, pageable);
System.out.println(page.getContent());//得到数据集合列表
System.out.println(page.getTotalElements());//得到总条数
System.out.println(page.getTotalPages());//得到总页数
}
查看結果:
方法对应关系
方法名称 | Sql对应关系 |
---|---|
equle | filed = value |
gt(greaterThan ) | filed > value |
lt(lessThan ) | filed < value |
ge(greaterThanOrEqualTo ) | filed >= value |
le( lessThanOrEqualTo) | filed <= value |
notEqule | filed != value |
like | filed like value |
notLike | filed not like value |