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

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;

@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:

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)