springjpa-crudRepository

截图1559220540.png

curdRepository继承自Repository，同时实现了基本的增删改查方法

package org.springframework.data.repository;
import java.util.Optional;
@NoRepositoryBean
public interface CrudRepository<T, ID> extends Repository<T, ID> {
    <S extends T> S save(S var1);//保存
    Optional<T> findById(ID var1);//id查询
    boolean existsById(ID var1);//是否存在
    Iterable<T> findAll();//查询全部
    long count();//统计个数
    void deleteById(ID var1);//id删除
    void deleteAll();//删除全部
    ...省略
}

下面是一个基本的例子。使用的h2内存数据库。

1. 项目github地址
2. postman测试文档

1. pom.xml

<?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>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.5.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.yanglimou</groupId>
    <artifactId>jpa-study</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>jpa-study</name>
    <description>Demo project for Spring Boot</description>

    <properties>
        <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-web</artifactId>
        </dependency>
        <!-- 使用内存数据库 -->
        <dependency>
            <groupId>com.h2database</groupId>
            <artifactId>h2</artifactId>
            <scope>runtime</scope>
        </dependency>

        <!-- 目的是将iterator转成list -->
        <dependency>
            <groupId>org.apache.commons</groupId>
            <artifactId>commons-collections4</artifactId>
            <version>4.3</version>
        </dependency>


    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

2. application.yaml

spring:
  datasource:
    # h2数据库的持久化文件地址
    url: jdbc:h2:file:~/jpastudy
    username: sa
    password:
    driver-class-name: org.h2.Driver
  jpa:
    hibernate:
      # 自动生成/修改表
      ddl-auto: update
    # 显示执行的sql语句
    show-sql: true

server:
  port: 8080
  tomcat:
    uri-encoding: UTF-8

3. JpaStudyApplication.java

package com.yanglimou.jpastudy;

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

@SpringBootApplication
public class JpaStudyApplication {

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

}

4. UserBean.java

package com.yanglimou.jpastudy.entity;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;

@Entity
public class User {
    @Id
    @GeneratedValue
    private Long id;
    private String name;
    private Integer age;
    private String city;

    public String getCity() {
        return city;
    }

    public void setCity(String city) {
        this.city = city;
    }

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Integer getAge() {
        return age;
    }

    public void setAge(Integer age) {
        this.age = age;
    }
}

5. UserRepository

package com.yanglimou.jpastudy.repository;

import com.yanglimou.jpastudy.entity.User;
import org.springframework.data.repository.CrudRepository;

public interface UserRepository extends CrudRepository<User, Long> {
}

6. UserService

package com.yanglimou.jpastudy.service;

import com.yanglimou.jpastudy.entity.User;
import com.yanglimou.jpastudy.repository.UserRepository;
import org.apache.commons.collections4.IteratorUtils;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.util.List;
import java.util.Optional;

@Service
public class UserService {
    @Autowired
    private UserRepository userRepository;

    public List<User> findAll() {
        Iterable<User> all = userRepository.findAll();
        List<User> users = IteratorUtils.toList(all.iterator());
        return users;
    }

    public User findById(Long id) {
        Optional<User> byId = userRepository.findById(id);
        return byId.orElse(null);//如果没有值返回空
    }

    //因为save方法是根据主键有没有值来进行增加或者修改的
    public User add(User user) {
        user.setId(null);
        User save = userRepository.save(user);
        return save;
    }

    public User update(Long id, User user) {
        if (userRepository.existsById(id)) {
            user.setId(id);
            User save = userRepository.save(user);
            return save;
        }
        return null;
    }

    public void delete(Long id) {
        if (userRepository.existsById(id))
            userRepository.deleteById(id);
    }

    public void deleteAll() {
        userRepository.deleteAll();
    }

    public Long count() {
        return userRepository.count();
    }
}

7. UserController

package com.yanglimou.jpastudy.controller;

import com.yanglimou.jpastudy.entity.User;
import com.yanglimou.jpastudy.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;

import java.util.List;


@RestController
@RequestMapping("/users")
public class UserController {
    @Autowired
    private UserService userService;

    @GetMapping("")
    public List<User> findAll() {
        return userService.findAll();
    }

    @GetMapping("/{id}")
    public User findById(@PathVariable Long id) {
        return userService.findById(id);
    }

    @PostMapping("")
    public User add(@RequestBody User user) {
        return userService.add(user);
    }

    @PutMapping("/{id}")
    public User add(@PathVariable Long id, @RequestBody User user) {
        return userService.update(id, user);
    }

    @DeleteMapping("{id}")
    public void delete(@PathVariable Long id) {
        userService.delete(id);
    }

    @DeleteMapping("")
    public void deleteAll() {
        userService.deleteAll();
    }

    @GetMapping("/count")
    public Long count() {
        return userService.count();
    }
}