springboot-5-整合jpa

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##springboot-parent.version: 1.5.

## jdk 1.8

## #######

在整合jpa之前, 先说下mysql

步骤:

　　1), 在application.properties中加入datasource配置

　　2), 在pom.xml中加入mysql依赖

　　3), 获取datasource的connection测试

然后, 配置连接池为druid

　　1), pom.xml中引入依赖　　　　

<dependency>

            <groupId>com.alibaba</groupId>

            <artifactId>druid</artifactId>

            <version>1.0.</version>

</dependency>

　　2), 配置application.properties数据源类型

　　3), 编写druid servlet和filter提供监控页面访问

jpa, 是一种规范, hibernate是他的一种实现方式

jpa是一种关于数据操作的 orm 对象/关系映射规范

springboot-5-整合jpa-LMLPHP

1, 引入依赖

<!-- 整合jpa使用 -->

        <dependency>

            <groupId>org.springframework.boot</groupId>

            <artifactId>spring-boot-starter-data-jpa</artifactId>

        </dependency>

        <!-- Spring Boot JDBC -->

        <dependency>

            <groupId>org.springframework.boot</groupId>

            <artifactId>spring-boot-starter-jdbc</artifactId>

        </dependency>

        <!--mysql驱动 -->

        <dependency>

            <groupId>mysql</groupId>

            <artifactId>mysql-connector-java</artifactId>

        </dependency>

2, 在src/main/source创建配置文件

application.yml

##### jpa #######

spring:

  datasource:

    url: jdbc:mysql://localhost:3306/test

    username: root

    password:

    driver-class-name: com.mysql.jdbc.Driver

  jpa:

    database: MYSQL

    show-sql: true

    hibernate:

      ddl-auto: update

#      naming:

#        implicit-strategy: org.hibernate.cfg.ImprovedNamingStrategy

    properties:   # 默认

      hibernate:

        dialect: org.hibernate.dialect.MySQL5Dialect

3, 在实体类上加入@Entity, 就可以进行crud操作了

package com.iwhere.test.demo;

import javax.persistence.Column;

import javax.persistence.Entity;

import javax.persistence.GeneratedValue;

import javax.persistence.GenerationType;

import javax.persistence.Id;

import javax.persistence.Table;

import javax.validation.constraints.NotNull;


// 生成表结构

@Entity
// 表名, 不写默认为类名

@Table(name="demo")

public class Demo {

　　// 主键

    @Id

　　// 主键生成策略

    @GeneratedValue(strategy=GenerationType.AUTO)

    private Integer id;

    @NotNull

    private String name;

    @Column(nullable=false)

    private String sex;

    public Integer 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 String getSex() {

        return sex;

    }

    public void setSex(String sex) {

        this.sex = sex;

    }

    public void setId(Integer id) {

        this.id = id;

    }

}

4, dao层继承接口即可

package com.iwhere.test.dao;

import org.springframework.data.repository.CrudRepository;

import com.iwhere.test.demo.Demo;

/**

 * 使用crud接口的dao层

 * @author 231

 *

 */

public interface DemoRepository extends CrudRepository<Demo, Long> {

}

5, service层调用

package com.iwhere.test.service;

import javax.annotation.Resource;

import org.springframework.stereotype.Service;

import org.springframework.transaction.annotation.Transactional;

import com.iwhere.test.dao.DemoRepository;

import com.iwhere.test.demo.Demo;

/**

 * service层

 * @author 231

 */

@Service

public class DemoService {

    @Resource

    private DemoRepository demoRepository;

    @Transactional

    public void save(Demo demo)     {

        demoRepository.save(demo);

    }

}

6, controller层执行

package com.iwhere.test.web;

import javax.annotation.Resource;

import org.springframework.web.bind.annotation.RequestMapping;

import org.springframework.web.bind.annotation.RestController;

import com.iwhere.test.demo.Demo;

import com.iwhere.test.service.DemoService;

@RestController

@RequestMapping("/demo")

public class DemoController {

    @Resource

    private DemoService demoService;

    /**

     * 返回json格式数据

     * @RestController

     * @return

     */

    @RequestMapping("/getDemo")

    public Demo getDemo() {

        Demo demo = new Demo();

        demo.setId();

        demo.setName("Angel");

        return demo;

    }

    /**

     * 测试jpa的使用

     * @return

     */

    @RequestMapping("/save")

    public String saveDemo() {

        Demo demo = new Demo();

        demo.setId();

        demo.setName("Angel");

        demo.setSex("female");

        demoService.save(demo);

        return "ok";

    }

    
　　/**测试自定义异常*/

//    @RequestMapping("/zeroExcetpion")

//    public int zeroException() {

//        System.err.println("zero");

//        return 1/0;

//    }

}

此时运行, 既可以在数据库看到demo的存入了

然后, 介绍下repository接口:

1, 空接口, 标记

2, 继承Repository接口后, 会被IOC容器识别为一个bean

3, 也可用@RepositoryDefinition注解来代替继承

4, 方法名即sql语句

5, 条件树形要用关键字链接

6, 可以使用@Query实现自定义jpql语句

jpa操作为接口操作, 一个方法既一个sql语句, 常见的接口如下表:

具体的关键字，使用方法和生产成SQL如下表所示: 原文地址: http://www.cnblogs.com/ityouknow/p/5891443.html

And	findByLastnameAndFirstname	… where x.lastname = ?1 and x.firstname = ?2
Or	findByLastnameOrFirstname	… where x.lastname = ?1 or x.firstname = ?2
Is,Equals	findByFirstnameIs,findByFirstnameEquals	… where x.firstname = ?1
Between	findByStartDateBetween	… where x.startDate between ?1 and ?2
LessThan	findByAgeLessThan	… where x.age < ?1
LessThanEqual	findByAgeLessThanEqual	… where x.age ⇐ ?1
GreaterThan	findByAgeGreaterThan	… where x.age > ?1
GreaterThanEqual	findByAgeGreaterThanEqual	… where x.age >= ?1
After	findByStartDateAfter	… where x.startDate > ?1
Before	findByStartDateBefore	… where x.startDate < ?1
IsNull	findByAgeIsNull	… where x.age is null
IsNotNull,NotNull	findByAge(Is)NotNull	… where x.age not null
Like	findByFirstnameLike	… where x.firstname like ?1
NotLike	findByFirstnameNotLike	… where x.firstname not like ?1
StartingWith	findByFirstnameStartingWith	… where x.firstname like ?1 (parameter bound with appended %)
EndingWith	findByFirstnameEndingWith	… where x.firstname like ?1 (parameter bound with prepended %)
Containing	findByFirstnameContaining	… where x.firstname like ?1 (parameter bound wrapped in %)
OrderBy	findByAgeOrderByLastnameDesc	… where x.age = ?1 order by x.lastname desc
Not	findByLastnameNot	… where x.lastname <> ?1
In	findByAgeIn(Collection ages)	… where x.age in ?1
NotIn	findByAgeNotIn(Collection age)	… where x.age not in ?1
TRUE	findByActiveTrue()	… where x.active = true
FALSE	findByActiveFalse()	… where x.active = false
IgnoreCase	findByFirstnameIgnoreCase	… where UPPER(x.firstame) = UPPER(?1)

分页查询

分页查询在实际使用中非常普遍了，spring data jpa已经帮我们实现了分页的功能，在查询的方法中，需要传入参数Pageable
,当查询中有多个参数的时候Pageable建议做为最后一个参数传入

Page<User> findALL(Pageable pageable);

Page<User> findByUserName(String userName,Pageable pageable);

Pageable 是spring封装的分页实现类，使用的时候需要传入页数、每页条数和排序规则

@Test

public void testPageQuery() throws Exception {

    int page=,size=;

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

    Pageable pageable = new PageRequest(page, size, sort);

    userRepository.findALL(pageable);

    userRepository.findByUserName("testName", pageable);

}

UPPER