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第11章—使用对象关系映射持久化数据—SpringBoot+SpringData+Jpa进行查询修改数据库

  • 奔驰宝马娱乐在线
  • 2019-09-26
  • 199人已阅读
简介SpringBoot+SpringData+Jpa进行查询修改数据库JPA由EJB3.0软件专家组开发,作为JSR-220实现的一部分。但它又不限于EJB3.0,你可以在Web应用

SpringBoot+SpringData+Jpa进行查询修改数据库

JPA由EJB 3.0软件专家组开发,作为JSR-220实现的一部分。但它又不限于EJB 3.0,你可以在Web应用、甚至桌面应用中使用。JPA的宗旨是为POJO提供持久化标准规范,由此可见,经过这几年的实践探索,能够脱离容器独立运行,方便开发和测试的理念已经深入人心了。Hibernate3.2+、TopLink 10.1.3以及OpenJPA都提供了JPA的实现。

JPA的总体思想和现有Hibernate、TopLink、JDO等ORM框架大体一致。总的来说,JPA包括以下3方面的技术:

ORM映射元数据

JPA支持XML和JDK5.0注解两种元数据的形式,元数据描述对象和表之间的映射关系,框架据此将实体对象持久化到数据库表中;

API

用来操作实体对象,执行CRUD操作,框架在后台替代我们完成所有的事情,开发者从繁琐的JDBC和SQL代码中解脱出来。

查询语言

这是持久化操作中很重要的一个方面,通过面向对象而非面向数据库的查询语言查询数据,避免程序的SQL语句紧密耦合。

例子:SpringBoot+SpringData+Jpa

这里我的Demo的结构图如下:

相关的代码如下:

pom.xml:

<?xml version="1.0" encoding="UTF-8"?><project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>com.beacon</groupId> <artifactId>springdata-jpa</artifactId> <version>0.0.1-SNAPSHOT</version> <packaging>jar</packaging> <description>Demo project for Spring Boot</description> <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>2.0.3.RELEASE</version> <relativePath/> <!-- lookup parent from repository --> </parent> <properties> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding> <java.version>1.8</java.version> </properties> <dependencies> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-test</artifactId> <scope>test</scope> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-configuration-processor</artifactId> <optional>true</optional> </dependency> <!--数据库组件--> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-data-jpa</artifactId> </dependency> <!--数据库组件--> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> </dependency> <dependency> <groupId>com.alibaba</groupId> <artifactId>druid</artifactId> <version>1.1.10</version> </dependency> <!--//添加AOP--> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-aop</artifactId> </dependency> <!-- Spring boot 引用Thymeleaf模板依赖包(Thymeleaf模板如果不适用,这里也可以不添加这段配置,Thymeleaf模板使用在下面会讲到) --> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-thymeleaf</artifactId> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-maven-plugin</artifactId> </plugin> </plugins> </build></project>

StudentController:

package com.example.springdatajpa.controller;import com.example.springdatajpa.entity.Student;import com.example.springdatajpa.service.StudentService;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.web.bind.annotation.GetMapping;import org.springframework.web.bind.annotation.PathVariable;import org.springframework.web.bind.annotation.RestController;import java.util.List;@RestControllerpublic class StudentController { @Autowired private StudentService studentService; @GetMapping("/getAllStu") public List<Student> getAllStu(){ return studentService.findAll(); } @GetMapping("/findById/{id}") public Student findById(@PathVariable("id")Integer id){ return studentService.findById(id); } //根据money查询 再根据age排序 @GetMapping("/findByMoney/{money}") public List<Student> findByMoney(@PathVariable("money")Integer money,Integer age){ return studentService.findByMoneyOrAgeOrderByAgeDesc(money,age); } @GetMapping("/findByName/{name}") public Student findByNameIgnoresCase(@PathVariable("name")String name){ return studentService.findByName(name); }}

StudentDao:

package com.example.springdatajpa.dao;import com.example.springdatajpa.entity.Student;import org.springframework.data.jpa.repository.JpaRepository;import java.util.List;public interface StudentDao extends JpaRepository<Student,Object> { Student findById(Integer id); public List<Student> findByMoneyOrAgeOrderByAgeDesc(Integer money, Integer age) ; Student findByName(String name);}

Student:

package com.example.springdatajpa.entity;import javax.persistence.Entity;import javax.persistence.GeneratedValue;import javax.persistence.Id;import javax.persistence.Table;@Entity@Table(name="student")public class Student { private Integer id; private String name; private Integer age; private String password; private Integer money; //注意:这里一定要在主键的get方法上加上这两个注解 // @Id // @GeneratedValue // 不然会报错找不到 @Id @GeneratedValue public Integer getId() { return id; } public void setId(Integer id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public Integer getAge() { return age; } public void setAge(Integer age) { this.age = age; } public String getPassword() { return password; } public void setPassword(String password) { this.password = password; } public Integer getMoney() { return money; } public void setMoney(Integer money) { this.money = money; } @Override public String toString() { return "Student{" + "id=" + id + ", name="" + name + """ + ", age=" + age + ", password="" + password + """ + ", money=" + money + "}"; }}

StudentService

package com.example.springdatajpa.service;import com.example.springdatajpa.entity.Student;import java.util.List;public interface StudentService { List<Student> findAll(); Student findById(Integer id); List<Student> findByMoneyOrAgeOrderByAgeDesc(Integer money, Integer age); Student findByName(String name);}

StudentServiceImpl

package com.example.springdatajpa.service.impl;import com.example.springdatajpa.dao.StudentDao;import com.example.springdatajpa.entity.Student;import com.example.springdatajpa.service.StudentService;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.stereotype.Service;import org.springframework.web.bind.annotation.PathVariable;import java.util.List;@Servicepublic class StudentServiceImpl implements StudentService { @Autowired private StudentDao studentDao; @Override public List<Student> findAll() { return studentDao.findAll(); } @Override public Student findById(Integer id) { return studentDao.findById(id); } @Override public List<Student> findByMoneyOrAgeOrderByAgeDesc(Integer money, Integer age) { return studentDao.findByMoneyOrAgeOrderByAgeDesc(money,age); } @Override public Student findByName(String name) { return studentDao.findByName(name); }}

application.yml:

server: port: 8089spring: datasource: url: jdbc:mysql://localhost:3306/test?useSSL=false username: root password: root driver-class-name: com.mysql.jdbc.Driver type: com.alibaba.druid.pool.DruidDataSource initialSize: 20 minIdle: 50 maxActive: 80 maxWait: 10000 timeBetweenEvictionRunsMillis: 60000 minEvictableIdleTimeMills: 300000 jpa: hibernate: ddl-auto: update generate-ddl: true show-sql: true# thymeleaf thymeleaf: prefix: classpath:templates/ suffix: .html mode: HTML5 encoding: utf-8 servlet: content-type: text/html cache: false

这里我们可以使用的是JPA的定义查询,相应的方法名的规则如下:

相应的演示如下:

访问:http://localhost:8089/getAllStu

访问:http://localhost:8089/findByMoney/9(这个地方可以把相应的数据查出来并按照相应的字段进行排序)

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