SpringBoot+JPA @Autowired注入泛型成员 封装统一接口

这是目录

• SpringBoot
• 实体类
• • `Media.java`
• 持久层
• • `IMediaRepository.java`
• 服务
• • `IService.java`
  • `IQueryService.java`
  • `baseService.java`
  • • 可以这样写
    • 还可以这样写
  • `MediaService.java`
• 控制器
• • `IController.java`
  • `baseController.java`
  • `MediaController.java`
• 测试接口

SpringBoot

输入java -version得到我的java version "16.0.1"。
cd到pom.xml文件所在位置即项目根目录并执行指令./mvnw dependency:list来查看引用版本：

• org.springframework.data:spring-data-jpa：2.5.2
• javax.validation:validation-api：2.0.1.Final
• com.alibaba:fastjson：1.2.78
• org.projectlombok:lombok：1.18.20
• org.springframework:spring-web：5.3.8
• org.springframework.boot:spring-boot：2.5.2

实体类 Media.java

一个很普通的实体类，包名省略。

package com.example.demo.entity;

import com.alibaba.fastjson.annotation.JSONField;
import java.io.Serializable;
import lombok.*;

import javax.persistence.*;

@SuppressWarnings({"LombokEqualsAndHashCodeInspection"})
@EqualsAndHashCode
@ToString
@Getter
@Setter
@Entity
@Table(name = "media")
@AllArgsConstructor
@NoArgsConstructor
public class Media implements Serializable
{
	@Id
	@JSONField(ordinal = 1)
	@GeneratedValue(strategy = GenerationType.IDENTITY)
	@Column(name = "id", insertable = false, updatable = false)
	private Integer id;
	@JSONField(ordinal = 2)
	@GeneratedValue(strategy = GenerationType.IDENTITY)
	@Column(name = "book_id", updatable = false)
	private Integer bookId;
	@JSONField(ordinal = 3)
	@GeneratedValue(strategy = GenerationType.IDENTITY)
	@Column(name = "url", length = 128)
	private String url;
}

持久层 IMediaRepository.java

一个啥也没有的接口。

package com.example.demo.repository;

import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.JpaSpecificationExecutor;
import com.example.demo.entity.Media;

public interface IMediaRepository extends
	JpaRepository,
	JpaSpecificationExecutor
{
}

服务

写一些接口。

IService.java

package com.example.demo.service;

import org.springframework.lang.Nullable;

public interface IService
{
	@Nullable
	T get(K primaryKey);
	
	@Nullable
	T addOrUpdate(T obj);
	
	boolean delete(K primaryKey);
}

IQueryService.java

package com.example.demo.service;

import java.util.*;

public interface IQueryService
{
	List find(int index, int size);
	
	long count();
	
	List find(int index, int size, Map colAndPatterns);
	
	long count(Map colAndPatterns);
}

baseService.java

抽象服务类。

可以这样写

package com.example.demo.service;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.domain.PageRequest;
import org.springframework.data.jpa.domain.Specification;
import org.springframework.data.jpa.repository.*;
import com.example.demo.util.Common;

import javax.persistence.criteria.*;
import javax.validation.constraints.*;
import java.util.*;

public abstract class baseService & JpaSpecificationExecutor>
	implements IService, IQueryService
{
	@Autowired
	protected R repo; // 让@Autowired自己找合适的类注入 
	
	...
	
	@SuppressWarnings({"UnnecessarySemicolon", "OverlyBroadCatchBlock"})
	@Override
	public final T addOrUpdate(@NotNull final T obj)
	{
		T ret = null;
		if (canAddOrUpdate(obj))
		{
			try
			{
				ret = repo.saveAndFlush(obj);
			}
			catch (Exception e)
			{
				e.printStackTrace();
			}
		}
		return ret;
	}
	
	protected abstract boolean canAddOrUpdate(final T obj);
}

还可以这样写

感觉这个比上面那种要好一点，减少一个泛型参数。

package com.example.demo.service;

public abstract class baseService implements IService, IQueryService
{
	@Autowired
	protected JpaRepository repo;
	@Autowired
	protected JpaSpecificationExecutor queryRepo; // 少一个泛型参数，多注入一次

	...

	@SuppressWarnings({"UnnecessarySemicolon", "OverlyBroadCatchBlock"})
	@Override
	public final T addOrUpdate(@NotNull final T obj)
	{
		T ret = null;
		if (canAddOrUpdate(obj))
		{
			try
			{
				ret = repo.saveAndFlush(obj);
			}
			catch (Exception e)
			{
				e.printStackTrace();
			}
			finally
			{
				;
			}
		}
		return ret;
	}
	
	protected abstract boolean canAddOrUpdate(final T obj);
}

MediaService.java

服务类指定了类参数，然后实现之前的baseService的抽象方法。

package com.example.demo.service;

import org.springframework.stereotype.Service;
import com.example.demo.entity.Media;
import com.example.demo.repository.IMediaRepository;

@Service(value = "mediaService")
public class MediaService extends baseService
{
}

或

```java
package com.example.demo.service;

import org.springframework.stereotype.Service;
import com.example.demo.entity.Media;

@Service(value = "mediaService")
public class MediaService extends baseService
{
	...
}

控制器 IController.java

接口

package com.example.demo.controller;

import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;

public interface IController
{
	@RequestMapping(method = RequestMethod.POST)
	String add(T body);
	
	@RequestMapping(method = RequestMethod.PUT)
	String update(T body);
	
	@RequestMapping(method = RequestMethod.DELETE)
	String delete(K id);
	
	@RequestMapping(value = "/list", method = RequestMethod.GET)
	String gets(Integer index, Integer size);
	
	@RequestMapping(method = RequestMethod.GET)
	String get(K id);
}

baseController.java

package com.example.demo.controller;

import com.alibaba.fastjson.JSON;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;
import com.example.demo.service.baseService;

@RestController
public abstract class baseController implements IController
{
	@Autowired
	protected baseService service;
	
	@Override
	public String add(@RequestBody final T body)
	{
		return JSON.toJSONString(service.addOrUpdate(body));
	}
	
	...

}

MediaController.java

方法头顶上的注解也是可以继承的，但是参数注解重写方法就得重新再加一遍，忽略这一点造成的bug很低级。

package com.example.demo.controller;

import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import com.example.demo.entity.Media;

@RestController
@RequestMapping("/media")
public class MediaController extends baseController
{
}

测试接口

跑通。