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

2022-12-20 22:22:48

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:

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

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;

@RestController

public 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;

@Service

public 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: 8089

spring:

  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:

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

相应的演示如下:

访问:http://localhost:8089/getAllStu

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

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)

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

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