springboot-5-整合jpa-白红宇

springboot-5-整合jpa

阅读量：6148 次

发布时间：2019-06-21

本文共 6596 字，大约阅读时间需要 21 分钟。

##########springboot-parent.version: 1.5.2## 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　　　　


                 
      
       com.alibaba
                  
      
       druid
                  
      
       1.0.18

　　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

1, 引入依赖


             
                 
      
       org.springframework.boot
                  
      
       spring-boot-starter-data-jpa
              
             
             
                 
      
       org.springframework.boot
                  
      
       spring-boot-starter-jdbc
              
             
             
                 
      
       mysql
                  
      
       mysql-connector-java

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: 123    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
     
       {}

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 */@Servicepublic 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(1);        demo.setName("Angel");        return demo;    }        /**     * 测试jpa的使用     * @return     */    @RequestMapping("/save")    public String saveDemo() {        Demo demo = new Demo();        demo.setId(1);        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bean3, 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

Keyword	Sample	JPQL snippet
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
      
        findALL(Pageable pageable);    Page
       
         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

@Testpublic void testPageQuery() throws Exception {    int page=1,size=10;    Sort sort = new Sort(Direction.DESC, "id");    Pageable pageable = new PageRequest(page, size, sort);    userRepository.findALL(pageable);    userRepository.findByUserName("testName", pageable);}