Springboot---REST风格、JPA实现GET\POST\PUT

pom.xml

• 仅写需要的依赖

<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>mysql</groupId>
			<artifactId>mysql-connector-java</artifactId>
		</dependency>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-data-jpa</artifactId>
		</dependency>
		 <dependency>
                <groupId>org.eclipse.persistence</groupId>
                <artifactId>javax.persistence</artifactId>
                <version>2.1.0</version>
            </dependency>
	</dependencies>

LuckmoneyController.java

• 使用postman类似软件发出URL请求
• 控制器接受URL请求
• 根据发送URL方式实现不同的操作请求

package ink.xlr.controller;

import ink.xlr.domain.Luckymoney;
import ink.xlr.repository.LuckmoneyRepository;
import ink.xlr.service.LuckmoneyService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;

import java.math.BigDecimal;
import java.util.List;
import java.util.Optional;

/**
 * @author 小龙人
 */
@RestController
public class LuckymoneyController {

    @Autowired
    private LuckmoneyRepository repository;

    /**
     * 获取红包列表
     * @return
     */
    @GetMapping("/luckymoneys")
    public List<Luckymoney> list() {
        return repository.findAll();
    }

    /**
     * 创建红包（发红包）
     */
    @PostMapping("/luckymoneys")
    public Luckymoney create(@RequestParam("producer")String producer,
                             @RequestParam("money")BigDecimal money) {
        Luckymoney luckymoney = new Luckymoney();
        luckymoney.setProducer(producer);
        luckymoney.setMoney(money);
        return repository.save(luckymoney);
    }

    /**
     * 通过id查询红包（不存返回null）
     * @param id
     * @return
     */
    @GetMapping("/luckymoneys/{id}")
    public Luckymoney findById(@PathVariable("id")Integer id) {
        return repository.findById(id).orElse(null);
    }

    /**
     * 更新红包
     */
    @PutMapping("/luckymoneys/{id}")
    public Luckymoney update(@PathVariable("id")Integer id,
                             @RequestParam("consumer")String consumer) {
        Optional<Luckymoney> optional = repository.findById(id);
        if (optional.isPresent()){
            Luckymoney luckymoney = optional.get();
            luckymoney.setId(id);
            luckymoney.setConsumer(consumer);
            return repository.save(luckymoney);
        }
        return null;
    }

}

• @RestController = @ResponseBody(返回结果解析为JSON) + @Controller(声明为控制器)
• @Autowired依赖注入（只根据类型），@Resource（默认根据名称）
• @GetMapping("/luckymoneys")接受Get方式发送的URL请求，作为REST中查询方式
• @PostMapping("/luckymoneys")接受Post方式发送的URL请求，作为REST中的创建方式
• @PutMapping("/luckymoneys/{id}")接受Put方式发送的URL请求，作为REST中的部分更新方式
• @RequestParam获取请求体中的参数
• @PathVariable获取请求路径中的参数

Luckmoney.java

package ink.xlr.domain;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import java.math.BigDecimal;

/**
 * @author 小龙人
 */
@Entity
public class Luckymoney {

    @Id
    @GeneratedValue
    private Integer id;

    private BigDecimal money;

    /**
     * 发送方
     */
    private String producer;

    /**
     * 接收方
     */
    private String consumer;

    public Luckymoney() {
    }

    public Integer getId() {
        return id;
    }
    // getter、setter、toString
}

• @Entity表明该类（Luckmoney）为实体类，对应数据库表名为luckmoney
• @Id表明属性为主键
• @GeneratedValue提供主键生成策略

application.yml或application.properties

spring:
  datasource:
    driver-class-name: com.mysql.jdbc.Driver
    url: jdbc:mysql://localhost:3306/luckymoney?serverTimezone=Asia/Shanghai&allowMultiQueries=true
    username: root
    password: 123456789
  jpa:
    hibernate:
      ddl-auto: update
    show-sql: true

• spring.jpa.hibernate.ddl-auto:update ->每次运行程序，没有表格会新建表格，表内若有数据，只更新
• spring.jpa.show-sql->显示每次执行的sql语句（便于出现错误查看SQL语句）

LuckmoneyRepository.java

package ink.xlr.repository;

import ink.xlr.domain.Luckymoney;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.stereotype.Repository;

/**
 * @author 小龙人
 */
@Repository
public interface LuckmoneyRepository extends JpaRepository<Luckymoney,Integer> {
}

• JpaRepository基于JPA的Respository接口，极大减少JPA作为数据访问的代码
• @Repository声明该类为数据访问组件

DemoApplication.java

package ink.xlr;

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

@SpringBootApplication
public class DemoApplication {

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

}