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SpringBoot集成JPA

2019-09-23 09:19:09来源：博客园阅读 ()

SpringBoot集成JPA

在SpringBoot中，通过Spring Data JPA 和 Spring Data Rest可以快速构建出一个RESTFul应用。

关于Spring Data JPA：JPA是一种规范，而Spring Data JPA可以有效简化关系型数据库访问代码。

关于Spring Data：Spring Data是Spring的一个子项目，致力于简化数据库访问。

JPA规范：

JPA中有种定义，将Java对象【POJO】映射到数据库。

@Entity（name=“t_book”）

表明该类为一个实体类，它默认对应数据库中的表名是t_book，在项目启动时会根据该类自动生成一张表。

【如果不配置name，默认表名为类名】

@Id

表示该属性是一个主键，@GeneratedValue(strategy = GenerationType.IDENTITY)表示主键自动生成，strategy表示主键生成策略。

创建工程

导入pom依赖

<?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>org.sang</groupId>
  <artifactId>jparestful</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  <packaging>jar</packaging>

  <name>jparestful</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/> <!-- 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-data-jpa</artifactId>
      </dependency>
      <dependency>
          <groupId>org.springframework.boot</groupId>
          <artifactId>spring-boot-starter-data-rest</artifactId>
      </dependency>
      <dependency>
          <groupId>com.alibaba</groupId>
          <artifactId>druid</artifactId>
          <version>1.1.9</version>
      </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>

配置数据库连接

spring.datasource.type=com.alibaba.druid.pool.DruidDataSource
spring.datasource.username=noneplus
spring.datasource.password=Noneplus564925080!
spring.datasource.url=jdbc:mysql://47.103.6.247:3306/restful-jpa?serverTimezone=UTC
spring.jpa.hibernate.ddl-auto=update
spring.jpa.database=mysql
spring.jpa.properties.hibernate.dialect=org.hibernate.dialect.MySQL57Dialect
spring.jpa.show-sql=true

##每页默认记录数，缺省值为20
#spring.data.rest.default-page-size=2
##分页查询页码参数名，缺省值为page
#spring.data.rest.page-param-name=page
##分页查询记录数参数名，缺省值为size
#spring.data.rest.limit-param-name=size
##分页查询排序参数名，缺省值为sort
#spring.data.rest.sort-param-name=sort
##base-path表示给所有请求路径都加上前缀
#spring.data.rest.base-path=/api
##添加成功时是否返回添加内容
#spring.data.rest.return-body-on-create=true
##更新成功时是否返回更新内容
#spring.data.rest.return-body-on-update=true

创建实体类

@Entity(name = "t_book")
public class Book {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Integer id;
    private String name;
    private String author;
    //省略getter/setter

    @Override
    public String toString() {
        return "Book{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", author='" + author + '\'' +
                '}';
    }

    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 String getAuthor() {
        return author;
    }

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

创建BookRepository

public interface BookRepository extends JpaRepository<Book, Integer> {

}

JpaRepository

//
// Source code recreated from a .class file by IntelliJ IDEA
// (powered by Fernflower decompiler)
//

package org.springframework.data.jpa.repository;

import java.util.List;
import org.springframework.data.domain.Example;
import org.springframework.data.domain.Sort;
import org.springframework.data.repository.NoRepositoryBean;
import org.springframework.data.repository.PagingAndSortingRepository;
import org.springframework.data.repository.query.QueryByExampleExecutor;

@NoRepositoryBean
public interface JpaRepository<T, ID> extends PagingAndSortingRepository<T, ID>, QueryByExampleExecutor<T> {
    List<T> findAll();

    List<T> findAll(Sort var1);

    List<T> findAllById(Iterable<ID> var1);

    <S extends T> List<S> saveAll(Iterable<S> var1);

    void flush();

    <S extends T> S saveAndFlush(S var1);

    void deleteInBatch(Iterable<T> var1);

    void deleteAllInBatch();

    T getOne(ID var1);

    <S extends T> List<S> findAll(Example<S> var1);

    <S extends T> List<S> findAll(Example<S> var1, Sort var2);
}

测试

【在进行这个节点测试之前，需要把代码的其他部分注释掉，之后会有一些自定义的功能】

在数据库添加几条测试数据

1569215934648

打开Postman，输入http://localhost:8080/books

【默认请求路径都是实体类名小写加s】

1569215981164

按照id查询

1569216056599

自定义请求路径

/**
 * 默认请求路径都是实体类名加s
 *
 * 自定义请求类名：
 * @RepositoryRestResource (path = "bs",collectionResourceRel = "bs",itemResourceRel = "b")
 * path属性指用bs替代原先的books，collectionResourceRel表示将返回的json集合中的book集合改为bs，
 * itemResourceRel表示将单个book的key改为b
 */
@RepositoryRestResource(path = "bs",collectionResourceRel = "bs",itemResourceRel = "b")
public interface BookRepository extends JpaRepository<Book, Integer> {

访问:http://localhost:8080/bs

1569216323418

自定义查询方法

     /**@RestResource注解定义：默认请求路径就是方法名，path可自定义路径
     * http://localhost:8080/bs/search/author?author=余华
     * http://localhost:8080/bs/search/name?name=白夜行
     * @param author
     * @return
     */
    @RestResource(path = "author",rel = "author")
    List<Book> findByAuthorContains(@Param("author") String author);
    @RestResource(path = "name",rel = "name")
    Book findByNameEquals(@Param("name") String name);

1569217053731