Spring Boot框架——整合持久层技术

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wx5c36e9d60110e 2022-06-05 01:18:09 ©著作权

文章标签 spring java mysql 文章分类 spring boot 后端开发

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Spring Boot 支持整合以下几种持久层技术

　　MyBatis

　　Hibernate

　　Spring Data

　　JdbcTemplate

Spring Boot 整合JdbcTemplate

JdbcTemplate 是 Spring ⾃带的 JDBC 模版组件，底层实现了对 JDBC 的封装，⽤法与 MyBatis 类似。开发者需要⾃定义 SQL 语句，JdbcTemplate 帮助开发者完成数据库连接，SQL 语句的执⾏，以及结果集的解析。

　　 JdbcTemplate 不⾜之处是灵活性不如 MyBatis，因为 MyBatis 的 SQL 定义在 XML 中，更有利⽤维护和扩展，但是 JdbcTemplate 是以硬编码的⽅式将 SQL 直接写在 Java 代码中，不利⽤扩展和维护。

　　 JdbcTemplate 对基本的 CRUD 操作提供了良好的⽀持，通过调⽤ query 和 update ⽅法即完成相关操作，其中 query 是⽤来做查询操作的，update 是⽤来做添加、删除、修改功能。

1、添加pom依赖

<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>

    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-jdbc</artifactId>
    </dependency>

    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>8.0.16</version>
    </dependency>

    <dependency>
        <groupId>org.projectlombok</groupId>
        <artifactId>lombok</artifactId>
    </dependency>
</dependencies>

2、配置application.xml

spring:
  datasource:
    url: jdbc:mysql://localhost:3306/mybatis
    username: root
    password: root
    driver-class-name: com.mysql.cj.jdbc.Driver

3、创建实体类

package com.sunjian.entity;

import lombok.Data;

@Data
public class Student {
    private Long id;
    private String name;
}

4、创建接口及实现类

package com.sunjian.repository;

import com.sunjian.entity.Student;

public interface StudentRepository {
    public Student findById(Long id);
}

package com.sunjian.repository.impl;

import com.sunjian.entity.Student;
import com.sunjian.repository.StudentRepository;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.jdbc.core.BeanPropertyRowMapper;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.stereotype.Repository;

@Repository
public class StudentRepositoryImpl implements StudentRepository {
    @Autowired
    private JdbcTemplate jdbcTemplate;

    @Override
    public Student findById(Long id) {
        return jdbcTemplate.queryForObject("select * from student where id = ?",new Object[]{id},new BeanPropertyRowMapper<Student>(Student.class));
    }
}

5、编写controller视图类

package com.sunjian.controller;

import com.sunjian.entity.Student;
import com.sunjian.repository.StudentRepository;
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;

@RestController
public class StudentController {
    @Autowired
    private StudentRepository studentRepository;

    @GetMapping("/findById/{id}")
    public Student findById(@PathVariable("id") Long id){
        return studentRepository.findById(id);
    }
}

6、启动项目，访问

query

　　1、queryForObject(String sql,Object[] args,RowMapper rowMapper)，查询⼀条记录，并且将结果集封装成 Java 对象。

　　2、query(String sql,RowMapper rowMapper)，查询⼀组数据，并且将结果集封装成集合对象。 RowMapper 是⼀个接⼝，作⽤就是解析结果集，将 JDBC 查询出的 ResultSet 对象转换为对应的 Java 对象，在调⽤该对象时需要指定⽬标类的结构，泛型。

update

　　update(String sql, Object... args) 参数：

　　1、要执⾏的 SQL 语句。

　　2、可变参数 Object... args，满⾜参数的可变性。

　　注意：如果，客户端⽤?传参 key-value 形式将数据传给 Spring MVC 服务端，业务⽅法的形参列表不需要添加任何注解即可⾃动封装参数 Java 对象。

　　如果，客户端传 JSON 格式数据，业务⽅法的形参列表需要添加 @RequestBody 注解，才能封装参数 Java 对象。

Spring Boot 整合 MyBatis

1、pom.xml

<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
    <!-- mysql -->
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
    </dependency>
    <!-- lombok -->
    <dependency>
        <groupId>org.projectlombok</groupId>
        <artifactId>lombok</artifactId>
        <version>1.18.8</version>
    </dependency>
    <!-- mybaits -->
    <dependency>
        <groupId>org.mybatis.spring.boot</groupId>
        <artifactId>mybatis-spring-boot-starter</artifactId>
        <version>2.0.0</version>
    </dependency>
</dependencies>

2、创建实体类

package com.sunjian.entity;

import lombok.Data;

@Data
public class Student {
    private Long id;
    private String name;
}

3、创建接口repository类

package com.sunjian.repository;

import com.sunjian.entity.Student;

import java.util.List;

public interface StudentRepository {
    public List<Student> findAll();
    public Student findById(Long id);
    public void save(Student student);
    public void update(Student student);
    public void deleteById(Long id);
}

4、在resources目录下创建UserRepository.xml文件，编写SQL语句

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.sunjian.repository.StudentRepository">
    <select id="findAll" resultType="Student">
        select * from student
    </select>

    <select id="findById" parameterType="java.lang.Long" resultType="Student">
        select * from student where id = #{id}
    </select>

    <insert id="save" parameterType="Student">
        insert into student(name) values(#{name})
    </insert>

    <update id="update" parameterType="Student">
        update student set name = #{name} where id = #{id}
    </update>

    <delete id="deleteById" parameterType="java.lang.Long">
        delete from student where id = #{id}
    </delete>
</mapper>

5、配置文件application.xml

spring:
  datasource:
    type: com.alibaba.druid.pool.DruidDataSource
    driver-class-name: com.mysql.jdbc.Driver
    username: root
    password: root
    url: jdbc:mysql://127.0.0.1:3306/sunjian2?&useSSL=false&serverTimezone=UTC

mybatis:
  mapper-locations: classpath:/mapping/*.xml
  type-aliases-package: com.sunjian.entity

6、编写controller视图类

package com.sunjian.controller;

import com.sunjian.entity.Student;
import com.sunjian.repository.StudentRepository;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;

import java.util.List;

@RestController
public class StudentHandler {
    @Autowired
    private StudentRepository studentRepository;

    @GetMapping("/findAll")
    public List<Student> findAll(){
        return studentRepository.findAll();
    }

    @GetMapping("/findById/{id}")
    public Student findById(@PathVariable("id") Long id){
        return studentRepository.findById(id);
    }

    @PostMapping("/save")
    public void save(@RequestBody Student student){
        studentRepository.save(student);
    }

    @PutMapping("/update")
    public void update(@RequestBody Student student){
        studentRepository.update(student);
    }

    @DeleteMapping("/deleteById/{id}")
    public void deleteById(@PathVariable("id") Long id){
        studentRepository.deleteById(id);
    }
}

7、启动类上添加@MapperScan注解，启动，访问

package com.sunjian;

import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
@MapperScan("com.sunjian.repository")
public class Application {
    public static void main(String[] args) {
        SpringApplication.run(Application.class,args);
    }
}

Spring Boot 整合 Spring Data JPA

1、pom.xml

<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
    <!-- mysql -->
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
    </dependency>
    <!-- lombok -->
    <dependency>
        <groupId>org.projectlombok</groupId>
        <artifactId>lombok</artifactId>
        <version>1.18.8</version>
    </dependency>
    <!-- JPA -->
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-data-jpa</artifactId>
    </dependency>
</dependencies>

2、application.xml

spring:
  datasource:
    type: com.alibaba.druid.pool.DruidDataSource
    driver-class-name: com.mysql.jdbc.Driver
    username: root
    password: root
    url: jdbc:mysql://127.0.0.1:3306/sunjian2?&useSSL=false&serverTimezone=UTC
    
  jpa:
    show-sql: true
    properties:
      hibernate:
        format_sql: true

3、编写实体类

package com.sunjian.entity;

import lombok.Data;

import javax.persistence.*;

@Data
@Entity
public class Student {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    @Column
    private String name;
}

　　@Entity 映射数据表

　　@Id　　主键

　　@GeneratedValue 自增

　　@Column　　普通列

4、编写repository接口及实现类

package com.southwind.repository;
import com.southwind.entity.Student;
import org.springframework.data.jpa.repository.JpaRepository;
public interface StudentRepository extends JpaRepository<Student,Long> {
　  public Student findByName(String name); // 根据规则（代码提示的）编写
}

5、编写controller类

package com.sunjian.controller;

import com.sunjian.entity.Student;
import com.sunjian.repository.StudentRepository;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;

import java.util.List;

@RestController
public class StudentHandler {
    @Autowired
    private StudentRepository studentRepository;

    @GetMapping("/findAll")
    public List<Student> findAll(){
        return studentRepository.findAll();
    }

    @GetMapping("/findById/{id}")
    public Student findById(@PathVariable("id") Long id){
        return studentRepository.findById(id).get();
    }

    @PostMapping("/save")
    public void save(@RequestBody Student student){
        studentRepository.save(student);
    }

    @PutMapping("/update")
    public void update(@RequestBody Student student){
        studentRepository.save(student);
    }

    @DeleteMapping("/deleteById/{id}")
    public void deleteById(@PathVariable("id") Long id){
        studentRepository.deleteById(id);
    }

    @GetMapping("/findByName/{name}")
    public Student findByName(@PathVariable("name") String name){
        return studentRepository.findByName(name);
    }
}