Spring Boot整合JPA

<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.tszr</groupId>
    <artifactId>chapter033</artifactId>
    <version>0.0.1-SNAPSHOT</version>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.3.RELEASE</version>
    </parent>

    <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>

        <!-- Spring Data JPA依赖启动器 -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>

        <!-- 阿里巴巴的Druid数据源依赖启动器 -->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid-spring-boot-starter</artifactId>
            <version>1.1.10</version>
        </dependency>

        <!-- MyBatis依赖启动器 -->
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>2.0.0</version>
        </dependency>
        <!-- MySQL数据库连接驱动 -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.28</version><!--$NO-MVN-MAN-VER$ -->
            <scope>runtime</scope>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <artifactId>maven-compiler-plugin</artifactId>
                <configuration>
                    <source>11</source>
                    <target>11</target>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

server:
  port: 8082
  
spring:
  datasource:
    name: druidDataSource
    type: com.alibaba.druid.pool.DruidDataSource
    druid:
      driver-class-name: com.mysql.cj.jdbc.Driver
      url: jdbc:mysql://localhost:3306/springbootdata?useUnicode=true&zeroDateTimeBehavior=convertToNull&autoReconnect=true&characterEncoding=utf-8
      username: root
      password: admin
      initial-size: 20
      min-idle: 10
      max-active: 100
      
mybatis:
  configuration:
    map-underscore-to-camel-case: true
  mapper-locations:
  - classpath:mapper/*.xml
  type-aliases-package: com.itheima.domain

package com.itheima.domain;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;

@Entity(name = "t_comment") // 设置ORM实体类，并指定映射的表名
public class Discuss {
    @Id // 表明映射对应的主键id
    @GeneratedValue(strategy = GenerationType.IDENTITY) // 设置主键自增策略
    private Integer id;
    private String content;
    private String author;
    @Column(name = "a_id") // 指定映射的表字段名
    private Integer aId;

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getContent() {
        return content;
    }

    public void setContent(String content) {
        this.content = content;
    }

    public String getAuthor() {
        return author;
    }

    public void setAuthor(String author) {
        this.author = author;
    }

    public Integer getaId() {
        return aId;
    }

    public void setaId(Integer aId) {
        this.aId = aId;
    }

    @Override
    public String toString() {
        return "Discuss{" + "id=" + id + ", content='" + content + '\'' + ", author='" + author + '\'' + ", aId=" + aId
                + '}';
    }
}

package com.itheima.repository;

import java.util.List;

import org.springframework.data.domain.Pageable;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.Modifying;
import org.springframework.data.jpa.repository.Query;
import org.springframework.transaction.annotation.Transactional;

import com.itheima.domain.Discuss;

public interface DiscussRepository extends JpaRepository<Discuss, Integer> {
    // 1、查询author非空的Discuss评论集合
    public List<Discuss> findByAuthorNotNull();

    // 2、根据文章id分页查询Discuss评论集合
    @Query("SELECT c FROM t_comment c WHERE  c.aId = ?1")
    public List<Discuss> getDiscussPaged(Integer aid, Pageable pageable);

    // 3、使用元素SQL语句，根据文章id分页查询Discuss评论集合
    @Query(value = "SELECT * FROM t_comment  WHERE  a_Id = ?1", nativeQuery = true)
    public List<Discuss> getDiscussPaged2(Integer aid, Pageable pageable);

    // 4、 根据评论id修改评论作者author
    @Transactional
    @Modifying
    @Query("UPDATE t_comment c SET c.author = ?1 WHERE  c.id = ?2")
    public int updateDiscuss(String author, Integer id);

    // 5、根据评论id删除评论
    @Transactional
    @Modifying
    @Query("DELETE t_comment c WHERE  c.id = ?1")
    public int deleteDiscuss(Integer id);
}

package com.itheima;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

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

package com.itheima;

import java.util.List;
import java.util.Optional;

import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.data.domain.Example;
import org.springframework.data.domain.ExampleMatcher;
import org.springframework.data.domain.ExampleMatcher.GenericPropertyMatchers;
import org.springframework.data.domain.PageRequest;
import org.springframework.data.domain.Pageable;
import org.springframework.test.context.junit4.SpringRunner;

import com.itheima.domain.Discuss;
import com.itheima.repository.DiscussRepository;

@RunWith(SpringRunner.class)
@SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
public class ApplicationTest {
    @Autowired
    private DiscussRepository repository;

    // 1、使用JpaRepository内部方法进行数据操作
    @Test
    public void selectComment() {
        Optional<Discuss> optional = repository.findById(1);
        if (optional.isPresent()) {
            System.out.println(optional.get());
        }
        System.out.println();
    }

    // 2、使用方法名关键字进行数据操作
    @Test
    public void selectCommentByKeys() {
        List<Discuss> list = repository.findByAuthorNotNull();
        System.out.println(list);
    }

    // 3、使用@Query注解进行数据操作
    @Test
    public void selectCommentPaged() {
        Pageable pageable = PageRequest.of(0, 3);
        List<Discuss> allPaged = repository.getDiscussPaged(1, pageable);
        System.out.println(allPaged);
    }

//  4、使用Example封装参数进行数据查询操作
    @Test
    public void selectCommentByExample() {
        Discuss discuss = new Discuss();
        discuss.setAuthor("张三");
        Example<Discuss> example = Example.of(discuss);
        List<Discuss> list = repository.findAll(example);
        System.out.println(list);
    }

    @Test
    public void selectCommentByExampleMatcher() {
        Discuss discuss = new Discuss();
        discuss.setAuthor("张");
        ExampleMatcher matcher = ExampleMatcher.matching().withMatcher("author", GenericPropertyMatchers.startsWith());
        Example<Discuss> example = Example.of(discuss, matcher);
        List<Discuss> list = repository.findAll(example);
        System.out.println(list);
    }
}