SpringBoot2.0使用Spring Data-JPA实现增删改查

旧城等待， 2022-05-20 22:29 318阅读 0赞

本文主要讲解使用springboot2.0使用jpa实现增删改查，外加自己拓展方法，spring的jpa是一个非常不错的持久层框架，可以理解为就是对Hibrenate进行了封装，比起Mybatis优点在于不用关注sql语句的编写。我这案例中使用ResultFul风格来编写的。  
好了讲了这么多废话直接上代码和步骤吧。使用的是maven管理项目，如果不会maven的同学可以先去学会使用maven吧。

第一步:新建一个springboot项目(pom文件直接拿走吧)

<?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.itpengwei.idea.one</groupId>
        <artifactId>springboot-jpa</artifactId>
        <version>0.0.1-SNAPSHOT</version>
        <packaging>jar</packaging>
    
        <name>springboot-jpa</name>
        <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/> 
        </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-data-jpa</artifactId>
            </dependency>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-web</artifactId>
            </dependency>
            
            <dependency>
                <groupId>mysql</groupId>
                <artifactId>mysql-connector-java</artifactId>
                <scope>runtime</scope>
            </dependency>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-test</artifactId>
                <scope>test</scope>
            </dependency>
        </dependencies>
    
        <build>
            <plugins>
                <plugin>
                    <groupId>org.springframework.boot</groupId>
                    <artifactId>spring-boot-maven-plugin</artifactId>
                </plugin>
            </plugins>
        </build>
    
    
    </project>

第二步:写yml配置文件（我这里写了两个，dev用于开发环境，prod用于生产环境）

![70][]

application.yml内容如下:

spring:
      profiles:
        active: dev

application-dev.yml如下:

server:
      port: 8080
    spring:
      datasource:
        url: jdbc:mysql://localhost:3306/springboot-test?useUnicode=true&characterEncoding=UTF-8&allowMultiQueries=true
        driver-class-name: com.mysql.jdbc.Driver
        username: root
        password: ***
      jpa:
       hibernate:
         ddl-auto: update
       show-sql: true

第三步:创建实体类并且使用注解描述实体和表的关系:

package com.itpengwei.sjpa.pojo;
    
    import javax.persistence.*;
    
    @Entity(name = "tb_student")
    public class Student {
        @Id
        @GeneratedValue
        @Column(name = "id", length = 32)
        private Long id;
        @Column(length = 50)
        private String name;
        @Column(length = 3)
        private Integer age;
    
        public Student() {
        }
    
        public Long getId() {
            return id;
        }
    
        public void setId(Long 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;
        }
    }

第四步:写个dao

package com.itpengwei.sjpa.dao;
    
    import com.itpengwei.sjpa.pojo.Student;
    import org.springframework.data.jpa.repository.JpaRepository;
    
    import java.util.List;
    //泛型中第一个参数是实体类，第二个是id类型
    public interface StudentDao extends JpaRepository<Student,Long> {
        //根据学生姓名查询数据
        public List<Student> findByName(String name);
    }

是不是发现特别简单这个dao，因为spring为我们封装了大量的方法

第五步:写service

package com.itpengwei.sjpa.service;
    
    import com.itpengwei.sjpa.dao.StudentDao;
    import com.itpengwei.sjpa.pojo.Student;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.stereotype.Service;
    import org.springframework.transaction.annotation.Transactional;
    
    import java.util.List;
    
    @Service
    @Transactional
    public class StudentService {
        @Autowired
        private StudentDao studentDao;
        //插入一个学生
        public void addStudent(Student student){
            studentDao.save(student);
        }
    
        //修改一个学生(jpa是根据id来修改的)
        public void  updateStudent(Student student){
            studentDao.save(student);
        }
        //根据id删除一条数据
        public void deleteStudentById(Long id){
            studentDao.deleteById(id);
        }
    
        //查询所有
        public List<Student> findAll(){
            return studentDao.findAll();
        }
        //根据id查询一条数据(2.0后不能使用findOne了)
        public Student findStudentById(Long id){
            return studentDao.findById(id).get();
        }
        //根据学生姓名查询多条数据
        public List<Student> findStudentByName(String name){
            return studentDao.findByName(name);
        }
    }

第六步:到controller了:

package com.itpengwei.sjpa.controller;
    
    import com.itpengwei.sjpa.common.CommonResult;
    import com.itpengwei.sjpa.pojo.Student;
    import com.itpengwei.sjpa.service.StudentService;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.web.bind.annotation.*;
    
    import java.util.List;
    
    @RestController
    public class StudentController {
        @Autowired
        private StudentService studentService;
    
        //添加一个学生
        @PostMapping(value = "/addStudent")
        public CommonResult addStudent(Student student) {
            CommonResult result = new CommonResult();
            try {
                studentService.addStudent(student);
                return result;
            } catch (Exception e) {
                e.printStackTrace();
                result.setState(500);
                result.setMsg("失败");
                return result;
            }
        }
    
        //修改一个学生(jpa是根据id来修改的)
        @PutMapping(value = "/updateStudent")
        public CommonResult updateStudentById(Student student) {
            CommonResult result = new CommonResult();
            try {
                studentService.updateStudent(student);
                return result;
            } catch (Exception e) {
                e.printStackTrace();
                result.setState(500);
                result.setMsg("失败");
                return result;
            }
        }
    
        //根据id删除一条数据
        @DeleteMapping(value = "/deleteStudent/{id}")
        public CommonResult deleteStudentById(@PathVariable(name = "id", required = true) Long id) {
            CommonResult result = new CommonResult();
            try {
                studentService.deleteStudentById(id);
                return result;
            } catch (Exception e) {
                e.printStackTrace();
                result.setState(500);
                result.setMsg("失败");
                return result;
            }
        }
    
        //查询所有
        @GetMapping(value = "/findAll")
        public CommonResult findAll() {
            CommonResult result = new CommonResult();
            try {
                List<Student> list = studentService.findAll();
                //将查询结果封装到CommonResult中
                result.setData(list);
                return result;
            } catch (Exception e) {
                e.printStackTrace();
                result.setState(500);
                result.setMsg("失败");
                return result;
            }
        }
    
        //根据id查询一条数据(2.0后不能使用findOne了)
        @GetMapping(value = "/findStudentById/{id}")
        public CommonResult findStudentById(@PathVariable(name = "id") Long id) {
            CommonResult result = new CommonResult();
            try {
                Student student = studentService.findStudentById(id);
                //将查询结果封装到CommonResult中
                result.setData(student);
                return result;
            } catch (Exception e) {
                e.printStackTrace();
                result.setState(500);
                result.setMsg("失败");
                return result;
            }
        }
    
        //根据学生姓名查询多条数据
        @GetMapping(value = "/findStudentByName")
        public CommonResult findStudentByName(String name) {
            CommonResult result = new CommonResult();
            try {
                List<Student> studentList = studentService.findStudentByName(name);
                //将查询结果封装到CommonResult中
                result.setData(studentList);
                return result;
            } catch (Exception e) {
                e.printStackTrace();
                result.setState(500);
                result.setMsg("失败");
                return result;
            }
        }
    }

这里我就讲我这个全局返回类也给贴出来吧

package com.itpengwei.sjpa.common;
    
    import java.util.List;
    
    public class CommonResult {
        private Integer state;
        private String msg;
        private Object data;
    
        public CommonResult() {
            this.state=200;
            this.msg="成功";
        }
    
        public CommonResult(Integer state, String msg) {
            this.state = state;
            this.msg = msg;
        }
    
        public CommonResult(Integer state, String msg, Object data) {
            this.state = state;
            this.msg = msg;
            this.data = data;
        }
    
        public Integer getState() {
            return state;
        }
    
        public void setState(Integer state) {
            this.state = state;
        }
    
        public String getMsg() {
            return msg;
        }
    
        public void setMsg(String msg) {
            this.msg = msg;
        }
    
        public Object getData() {
            return data;
        }
    
        public void setData(Object data) {
            this.data = data;
        }
    }

第七步:启动项目开始进行测试:

启动成功，数据库已经创出了表

![70 1][]

控制台输出了建表语句

![70 2][]

测试添加一个学生:

![70 3][]

修改一个学生数据:

![70 4][]

根据id删除一条数据:

![70 5][]

查询所有数据:

![70 6][]

根据id查询一条数据:

![70 7][]

根据姓名查询:

![70 8][]

[70]: /images/20220521/e1e49ed551d943b798674869406efbe6.png
[70 1]: /images/20220521/f0a0b62543b0408cac78af10f2f8b7b2.png
[70 2]: /images/20220521/245d9786ad7b4270b288eb062d28f8c9.png
[70 3]: /images/20220521/ebfeefa015cd4b70ae6b3f2ce3e03040.png
[70 4]: /images/20220521/0bdb3d0f615e4b5f8b8dc496a19fa85c.png
[70 5]: /images/20220521/9ebb3104a71043efba68b50532bf9728.png
[70 6]: /images/20220521/0ae24376ccf84e4692a1797022a33e36.png
[70 7]: /images/20220521/cebf061f05ce4700b6b850bf892537e7.png
[70 8]: /images/20220521/822d512ec25c40e4bd735ffdf2319359.png