Spring

使用Spring Data REST

介绍

Spring Data REST是个快速构建REST服务的脚手架，这里整个项目是基于Spring Boot的

下载依赖

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<dependencies>
  <dependency>
    <groupId>org.springframework.data</groupId>
    <artifactId>spring-data-jpa</artifactId>
  </dependency>
  <dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-data-rest</artifactId>
  </dependency>
<dependencies>

实体类映射

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package com.example.demo;

import lombok.Data;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.OneToMany;
import java.util.List;

@Data
@Entity
public class Student {
    @Id
    @GeneratedValue
    private long id;

    private String name;
}

配置数据DAO

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package com.example.demo;

import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.rest.core.annotation.RepositoryRestResource;

@RepositoryRestResource
public interface StudentRepository extends JpaRepository<Student, Long> {
}

CRUD

对于集合资源

GET 返回资源，通过page、size和sort来控制返回的数据
POST 创建一个新的资源
HEAD 资源是否可用

除了这些外，其他请求都不支持

对于单个资源

GET 返回单个资源
HEAD 返回资源是否可用
PUT 替换资源
PATCH 部分更新资源
DELETE 删除资源

对于关联的资源

GET 获取资源

Create

新建使用POST

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curl -X POST \
  http://localhost:8080/students \
  -H 'Cache-Control: no-cache' \
  -H 'Content-Type: application/json' \
  -H 'Postman-Token: 01b18db0-58a2-4315-8df3-0f783f8d13d0' \
  -d '{
	"name": "Jobs"
}'

Read

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读取采用GET
curl -X GET http://localhost:8080/students

curl -X GET http://localhost:8080/students/1

Update

更新使用PUT

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curl -X PUT \
  http://localhost:8080/students/1 \
  -H 'Cache-Control: no-cache' \
  -H 'Content-Type: application/json' \
  -H 'Postman-Token: 0b4029f6-42ba-4c79-9c31-b2f1cb884898' \
  -d '{
	"name": "James"
}'

Delete

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curl -X DELETE \
  http://localhost:8080/students/1 \
  -H 'Cache-Control: no-cache' \
  -H 'Content-Type: application/json' \
  -H 'Postman-Token: c13c0395-eb18-4b43-b16f-8cea06f5f0b0' \
  -d '{
	"name": "James"
}'

对于关联资源的CRUD

这个是被关联的资源

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package com.example.demo;

import lombok.Data;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.OneToMany;
import java.util.List;

@Data
@Entity
public class Teacher {
    @Id
    @GeneratedValue
    private Long id;

    private String name;
}

这事包含关联资源的类

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package com.example.demo;

import lombok.Data;
import org.springframework.data.annotation.LastModifiedDate;

import javax.persistence.*;
import java.util.Date;
import java.util.List;

@Data
@Entity
public class Student {
    @Id
    @GeneratedValue
    private long id;
    @Version
    private long version;
    @LastModifiedDate
    private Date date;

    private String name;

    @OneToMany
    private List<Teacher> teachers;
}

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package com.example.demo;

import lombok.Data;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.OneToMany;
import java.util.List;

@Data
@Entity
public class Teacher {
    @Id
    @GeneratedValue
    private Long id;

    private String name;
}

Create

  1. 先插入两个教师
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curl -X POST http://localhost:8080/teachers -d '{ "name": "James Hadden" }'
curl -X POST http://localhost:8080/teachers -d '{ "name": "Crise Pual" }'

教师的ID分别为1， 2

  1. 新建学生
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curl -X POST http://localhost:8080/students -d '{ "name": "James Hadden", "teachers": [
  "http://localhost:8080/teachers/1", "http://localhost:8080/teachers/1"
] }'

这个时候会新建成功，并且教师的信息也会关联到学生上

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curl -X POST http://localhost:8080/students -d '{ "name": "James Hadden", "teachers": [
  "http://localhost:8080/teachers/1", "http://localhost:8080/teachers/1"
] }'

我们再次插入学生信息，这个时候数据库就会报错了，因为@OneToMany注解是一个教师只能属于一个学生。这个时候注解应该改为@ManyToMany，这个时候就能插入了

Update

未完待续！