使用spring-data-jpa實(shí)現(xiàn)簡(jiǎn)單的兩表聯(lián)查實(shí)踐

更新時(shí)間：2026年06月02日 10:30:28 作者：快起來(lái)寫bug了

本文介紹了Spring Data JPA在Spring Boot中的配置與簡(jiǎn)單操作,涵蓋一對(duì)多和多對(duì)一關(guān)系的處理,適合初學(xué)者學(xué)習(xí),通過(guò)配置數(shù)據(jù)源、創(chuàng)建實(shí)體類和DAO接口,實(shí)現(xiàn)基本的CRUD操作,并提供了一個(gè)簡(jiǎn)單的示例

spring-data-jpa實(shí)現(xiàn)簡(jiǎn)單的兩表聯(lián)查

關(guān)于Spring-data-jpa的配置+Springboot+Spring-data-jpa的簡(jiǎn)單操作簡(jiǎn)單操作+分布式服務(wù)設(shè)置一個(gè)永遠(yuǎn)不重復(fù)的ID

初學(xué)Spring套餐家族中的Spring-data-jpa發(fā)現(xiàn)可以更簡(jiǎn)單的實(shí)現(xiàn)一些基本的增刪改查，以下是一些基礎(chǔ)操作，希望可以給初學(xué)者一些幫助

spring家族

Spring Boot
spring Cloud
Spring framework
Spring-data
	Spring data-jpa(簡(jiǎn)單的增刪改查)

jpa配置

jpa的底層是基于hibernate

多表聯(lián)查的時(shí)候會(huì)用到一對(duì)多,多對(duì)一的關(guān)系等

springboot一旦是一個(gè)web程序,記得配置數(shù)據(jù)源

spring:
  datasource:
    driver-class-name: com.mysql.cj.jdbc.Driver
    username: root
    password: root
    url: jdbc:mysql://localhost:3306/studentdb?useUnicode=true&characterEncoding=utf-8&serverTimezone=UTC&zeroDateTimeBehavior=CONVERT_TO_NULL
  jpa:
    database: mysql
    hibernate:
      ddl-auto: update
      naming:
        physical-strategy: org.hibernate.boot.model.naming.PhysicalNamingStrategyStandardImpl
    show-sql: true
  profiles:
    active: local

實(shí)體類快速建表

@Data
@Entity
public class Student {
    @Id
    private Long stuid;
    private String name;
    private String sex;
    @ManyToOne
    private Grade grade;
}

Id列的注解

@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
/*Id表示主鍵  主鍵有生成策略*/
/*GenerationType.IDENTITY唯一列還自動(dòng)增長(zhǎng)*/
/*GenerationType.AUTO自動(dòng)增長(zhǎng)*/
/*Oracle中是沒(méi)有自動(dòng)增長(zhǎng)的 設(shè)置GenerationType.SEQUENCE  使用序列進(jìn)行增長(zhǎng)*/
/*GeneratedValue 自動(dòng)增長(zhǎng)生成的value值*/

普通列注解

@Column

啟動(dòng)后自動(dòng)建表成功

Dao(數(shù)據(jù)訪問(wèn)層)接口

public interface StudentMapper extends JpaRepository<Student,Long>, JpaSpecificationExecutor<Student> {
}

ServiceImpl類

@Service
public class StudentServiceImpl {

    @Autowired
    private StudentMapper studentMapper;

    public Page<Student> students(Integer pageNum, Integer size){
        if(pageNum==null||pageNum<0){
            pageNum=0;
        }
        if (size==null){
            size=2;
        }
        return studentMapper.findAll(PageRequest.of(pageNum,size));
    }

    public void del(Long id){
        try {
            studentMapper.deleteById(id);
        }catch (Exception e){
            e.printStackTrace();
        }
    }

    public Student getByid(Long id){
        Optional<Student> byId = studentMapper.findById(id);
        return byId.get();
    }

    public Student add(Student student){
        return studentMapper.save(student);
    }

    public Student upd(Student student){
        return studentMapper.save(student);
    }
}

因?yàn)閕d我沒(méi)有給自增所以要手動(dòng)給id并且不能重復(fù)

先創(chuàng)建工具類

public class IdWorker {
    // 時(shí)間起始標(biāo)記點(diǎn)，作為基準(zhǔn)，一般取系統(tǒng)的最近時(shí)間（一旦確定不能變動(dòng)）
    private final static long twepoch = 1288834974657L;
    // 機(jī)器標(biāo)識(shí)位數(shù)
    private final static long workerIdBits = 5L;
    // 數(shù)據(jù)中心標(biāo)識(shí)位數(shù)
    private final static long datacenterIdBits = 5L;
    // 機(jī)器ID最大值
    private final static long maxWorkerId = -1L ^ (-1L << workerIdBits);
    // 數(shù)據(jù)中心ID最大值
    private final static long maxDatacenterId = -1L ^ (-1L << datacenterIdBits);
    // 毫秒內(nèi)自增位
    private final static long sequenceBits = 12L;
    // 機(jī)器ID偏左移12位
    private final static long workerIdShift = sequenceBits;
    // 數(shù)據(jù)中心ID左移17位
    private final static long datacenterIdShift = sequenceBits + workerIdBits;
    // 時(shí)間毫秒左移22位
    private final static long timestampLeftShift = sequenceBits + workerIdBits + datacenterIdBits;

    private final static long sequenceMask = -1L ^ (-1L << sequenceBits);
    /* 上次生產(chǎn)id時(shí)間戳 */
    private static long lastTimestamp = -1L;
    // 0，并發(fā)控制
    private long sequence = 0L;

    private final long workerId;
    // 數(shù)據(jù)標(biāo)識(shí)id部分
    private final long datacenterId;

    public IdWorker(){
        this.datacenterId = getDatacenterId(maxDatacenterId);
        this.workerId = getMaxWorkerId(datacenterId, maxWorkerId);
    }
    /**
     * @param workerId
     *            工作機(jī)器ID
     * @param datacenterId
     *            序列號(hào)
     */
    public IdWorker(long workerId, long datacenterId) {
        if (workerId > maxWorkerId || workerId < 0) {
            throw new IllegalArgumentException(String.format("worker Id can't be greater than %d or less than 0", maxWorkerId));
        }
        if (datacenterId > maxDatacenterId || datacenterId < 0) {
            throw new IllegalArgumentException(String.format("datacenter Id can't be greater than %d or less than 0", maxDatacenterId));
        }
        this.workerId = workerId;
        this.datacenterId = datacenterId;
    }
    /**
     * 獲取下一個(gè)ID
     *
     * @return
     */
    public synchronized long nextId() {
        long timestamp = timeGen();
        if (timestamp < lastTimestamp) {
            throw new RuntimeException(String.format("Clock moved backwards.  Refusing to generate id for %d milliseconds", lastTimestamp - timestamp));
        }

        if (lastTimestamp == timestamp) {
            // 當(dāng)前毫秒內(nèi)，則+1
            sequence = (sequence + 1) & sequenceMask;
            if (sequence == 0) {
                // 當(dāng)前毫秒內(nèi)計(jì)數(shù)滿了，則等待下一秒
                timestamp = tilNextMillis(lastTimestamp);
            }
        } else {
            sequence = 0L;
        }
        lastTimestamp = timestamp;
        // ID偏移組合生成最終的ID，并返回ID
        long nextId = ((timestamp - twepoch) << timestampLeftShift)
                | (datacenterId << datacenterIdShift)
                | (workerId << workerIdShift) | sequence;

        return nextId;
    }

    private long tilNextMillis(final long lastTimestamp) {
        long timestamp = this.timeGen();
        while (timestamp <= lastTimestamp) {
            timestamp = this.timeGen();
        }
        return timestamp;
    }

    private long timeGen() {
        return System.currentTimeMillis();
    }

    /**
     * <p>
     * 獲取 maxWorkerId
     * </p>
     */
    protected static long getMaxWorkerId(long datacenterId, long maxWorkerId) {
        StringBuffer mpid = new StringBuffer();
        mpid.append(datacenterId);
        String name = ManagementFactory.getRuntimeMXBean().getName();
        if (!name.isEmpty()) {
         /*
          * GET jvmPid
          */
            mpid.append(name.split("@")[0]);
        }
      /*
       * MAC + PID 的 hashcode 獲取16個(gè)低位
       */
        return (mpid.toString().hashCode() & 0xffff) % (maxWorkerId + 1);
    }

    /**
     * <p>
     * 數(shù)據(jù)標(biāo)識(shí)id部分
     * </p>
     */
    protected static long getDatacenterId(long maxDatacenterId) {
        long id = 0L;
        try {
            InetAddress ip = InetAddress.getLocalHost();
            NetworkInterface network = NetworkInterface.getByInetAddress(ip);
            if (network == null) {
                id = 1L;
            } else {
                byte[] mac = network.getHardwareAddress();
                id = ((0x000000FF & (long) mac[mac.length - 1])
                        | (0x0000FF00 & (((long) mac[mac.length - 2]) << 8))) >> 6;
                id = id % (maxDatacenterId + 1);
            }
        } catch (Exception e) {
            System.out.println(" getDatacenterId: " + e.getMessage());
        }
        return id;
    }

注入

@SpringBootApplication
public class SpringDataJpa01Application {

    public static void main(String[] args) {
        SpringApplication.run(SpringDataJpa01Application.class, args);
    }

    @Bean
    public IdWorker sb(){
        return new IdWorker();
    }
}

調(diào)用新增方法是執(zhí)行

Controller(控制層)類

@Controller
public class StudentController {

    @Autowired
    private StudentServiceImpl studentService;
    @Autowired
    private GradeMapper gradeMapper;
    @Autowired
    private IdWorker idWorker;

    @GetMapping("/students")
    public String findAll(Integer pageNum, Integer size, Model model) {
        Page<Student> students = studentService.students(pageNum, size);
        model.addAttribute("students", students);
        return "index";
    }

    @DeleteMapping("/student/{id}")
    public String del(@PathVariable("id") Long id) {
        studentService.del(id);
        return "redirect:/students";
    }

    @GetMapping("/student")
    public String edit(Long id, Model model) {
        model.addAttribute("grades", gradeMapper.findAll());
        if (id != null) {
            model.addAttribute("students", studentService.getByid(id));
        }
        return "edit";
    }

    @PostMapping("/student")
    public String add(Student student) {
        student.setStuid(idWorker.nextId());
        studentService.add(student);
        return "redirect:/students";
    }

    @PutMapping("/student")
    public String upd(Student student) {
        studentService.upd(student);
        return "redirect:/students";
    }
}

index.html頁(yè)面

首頁(yè)

<!DOCTYPE html>
<html lang="en" xmlns:th="http://www.thymeleaf.org">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<table border="1">
    <a th:href="@{/student}" rel="external nofollow" >添加</a>
    <form action="">
        name：<input type="text">
        <input type="submit" value="搜索">
    </form>
    <tr>
        <td>#</td>
        <td>姓名</td>
        <td>性別</td>
        <td>年級(jí)</td>
        <td>操作</td>
    </tr>
    <tr th:each="stu : ${students}">
        <td th:text="${stu.stuid}">#</td>
        <td th:text="${stu.name}">姓名</td>
        <td th:text="${stu.sex}">性別</td>
        <td th:text="${stu.grade.name}">年級(jí)</td>
        <td>
            <button class="del" th:attr="del_uri=@{/student/}+${stu.stuid}">刪除</button>
            <a th:href="@{/student(id=${stu.stuid})}" rel="external nofollow" >修改</a>
        </td>
    </tr>
</table>
<form id="DelFoem" action="" method="post">
    <input type="hidden" name="_method" value="delete">
</form>
<a th:href="@{/students(pageNum=1)}" rel="external nofollow" >首頁(yè)</a>
<a th:href="@{/students(pageNum=${students.number}-1)}" rel="external nofollow" >上一頁(yè)</a>
<a th:if="${students.hasNext()}" th:href="@{/students(pageNum=${students.number}+1)}" rel="external nofollow" >下一頁(yè)</a>
<a th:if="${!students.hasNext()}" th:href="@{/students(pageNum=${students.totalPages}-1)}" rel="external nofollow"  rel="external nofollow" >下一頁(yè)</a>
<a th:href="@{/students(pageNum=${students.totalPages}-1)}" rel="external nofollow"  rel="external nofollow" >尾頁(yè)</a>
共[[${students.totalPages}]]頁(yè)，當(dāng)前第[[${students.number}+1]]
</body>
<script type="text/javascript" th:src="@{/js/jquery-1.12.4.js}"></script>
<script type="text/javascript">
    $(".del").click(function () {
        $("#DelFoem").attr("action", $(this).attr("del_uri")).submit();
    })
</script>
</html>

添加修改頁(yè)面

<!DOCTYPE html>
<html lang="en" xmlns:th="http://www.thymeleaf.org">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<table>
    <form th:action="@{/student}" method="post">
        <input type="hidden" name="_method" value="put" th:if="${students!=null}">
        <input type="hidden" name="stuid" th:value="${students?.stuid}" th:if="${students!=null}">
        <tr>
            <td>name:<input type="text" name="name" th:value="${students?.name}"></td>
        </tr>
        <tr>
            <td>sex:<input type="text" name="sex" th:value="${students?.sex}"></td>
        </tr>
        <tr>
            <td>grade:
                <select name="grade.gradeId">
                    <option th:each="grade : ${grades}"
                            th:value="${grade.gradeId}"
                            th:text="${grade.name}"
                    th:selected="${students!=null&&students?.grade.gradeId==grade.gradeId}"></option>
            </select></td>
        </tr>
        <tr>
            <td>
                <input type="submit" th:value="${students==null?'添加':'修改'}">
            </td>
        </tr>
    </form>
</table>
</body>
</html>