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

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】

按照id查询

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

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);

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代码参考

https://github.com/hcj-shadow/springbootplus