SpringDataJpa开发--继承JpaRepository实现简单条件查询

拼搏现实的明天。 2023-10-17 22:38 26阅读 0赞

1.Spring Data JPA 是 Spring Data 技术下的子项目，使用Spring Data JPA 访问数据只需要数据访问层接口实现JpaRepository接口即可。

2.JpaRepository接口继承了PagingAndSortingRepository接口，所以也有它的一些功能

3.JpaRepoditory接口提供了很多常用方法：

![70][]

**示例：简单条件查询**

按照Spring Data 的规则，我们可以通过定义在Repository接口下的方法来执行查询等操作

查询的方法必须以find、get、read开头，同时涉及条件查询时，Spring Data Jpa支持将条件属性定义在数据访问层接口下的方法名中

条件属性通过条件关键字连接。

条件属性的首字母必须大写

①**创建一个Maven项目，在src/main下新建一个名为resources的文件夹，修改pom.xml**

<groupId>com.ysh</groupId>  
<artifactId>simplespringdatajpatest</artifactId>  
<version>0.0.1-SNAPSHOT</version>  
<packaging>jar</packaging>

<name>simplespringdatajpatest</name>  
<url>http://maven.apache.org</url>

<parent>  
<groupId>org.springframework.boot</groupId>  
<artifactId>spring-boot-starter-parent</artifactId>  
<version>2.0.0.RELEASE</version>  
<relativePath/>  
</parent>  
  
<properties>  
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>  
<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>  
<java.version>1.8</java.version>  
</properties>

<dependencies>  
  
  
<dependency>  
<groupId>org.springframework.boot</groupId>  
<artifactId>spring-boot-starter-web</artifactId>  
</dependency>  
  
  
<dependency>  
<groupId>org.springframework.boot</groupId>  
<artifactId>spring-boot-starter-thymeleaf</artifactId>  
</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>junit</groupId>  
<artifactId>junit</artifactId>  
<scope>test</scope>  
</dependency>  
</dependencies>  
</project>

②**配置基本属性**

在src/main/resources下新建一个全局配置文件，命名为application.properties

\#数据库地址，其中springdatajpa是数据库名称

spring.datasource.url=jdbc:mysql://localhost:3306/springdatajpa

\#数据库用户名

spring.datasource.username=root

\#数据库密码，要改成自己的密码

spring.datasource.password=yourpassword

\#数据库驱动，固定格式

spring.datasource.driverClassName=com.mysql.jdbc.Driver

\#指定连接池中最大的活跃连接数

spring.datasource.max-active=20

\#指定连接池最大的空闲连接

spring.datasource.max-idle=8

\#指定必须保持连接的最小值

spring.datasource.min-idle=8

spring.datasource.initial-size=10

\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#  
\#\#\# JPA持久化配置  
\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#  
\# 指定数据库类型  
spring.jpa.database= MySQL  
\# 指定是否需要在日志中显示sql语句  
spring.jpa.show-sql=true  
\# 指定自动创建|更新|验证数据库表结构等配置  
\# 表示如果数据库中存在持久化类对应的表就不创建，不存在就创建对应的表  
spring.jpa.hibernate.ddl-auto= update  
\# 指定命名策略  
spring.jpa.hibernate.naming-strategy=org.hibernate.cfg.ImprovedNamingStrategy  
\#指定数据库方言  
spring.jpa.properties.hibernate.dialect=org.hibernate.dialect.MySQL5Dialect

③**创建持久化类**

在com.ysh下新建4个包，bean(放置持久化类)、controller(控制器)、repository(定义数据访问接口的类)、service(业务逻辑处理类)

在bean下创建持久化类Student.java

package com.ysh.simplespringdatajpatest.bean;

import java.io.Serializable;

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

@Entity  
@Table(name="tb\_student")  
public class Student implements Serializable\{

private static final long serialVersionUID = 1L;  
  
@Id  
@GeneratedValue(strategy = GenerationType.IDENTITY)  
private int id;  
private String name ;  
private String address ;  
private int age ;  
private char sex;  
public int getId() \{  
return id;  
\}  
public void setId(int id) \{  
this.id = id;  
\}  
public String getName() \{  
return name;  
\}  
public void setName(String name) \{  
this.name = name;  
\}  
public String getAddress() \{  
return address;  
\}  
public void setAddress(String address) \{  
this.address = address;  
\}  
public int getAge() \{  
return age;  
\}  
public void setAge(int age) \{  
this.age = age;  
\}  
public char getSex() \{  
return sex;  
\}  
public void setSex(char sex) \{  
this.sex = sex;  
\}  
\}

④**定义数据访问层接口**

在repository包下新建一个接口，命名为StudentRepository,让该接口继承PagingAndSortingRepository

package com.ysh.simplespringdatajpatest.repository;

import java.util.List;

import org.springframework.data.jpa.repository.JpaRepository;

import com.ysh.simplespringdatajpatest.bean.Student;

public interface StudentRepository extends JpaRepository<Student, Integer> \{

/\*\*  
\* 通过学生姓名来查询学生对象  
\* 此方法相当于JPQL语句代码:select s from Student s where s.name = ?1  
\* @param name 参数  
\* @return Student对象  
\*/  
Student findByName(String name);  
  
/\*\*  
\* 通过名字和地址查询学生信息  
\* 此方法相当于JPQL语句代码:select s from Student s where s.name = ?1 and s.address=?2  
\* @param name  
\* @param address  
\* @return 包含Student对象的List集合  
\*/  
List<Student> findByNameAndAddress(String name , String address);  
  
/\*\*  
\* 通过学生姓名模糊查询学生信息  
\* 此方法相当于JPQL语句代码:select s from Student s where s.name like ?1  
\* @param name 参数  
\* @return 包含Student对象的List集合  
\*/  
List<Student> findByNameLike(String name);  
  
\}

⑤**定义业务层类**

StudentService.java

package com.ysh.simplespringdatajpatest.service;

import java.util.List;

import javax.annotation.Resource;

import org.springframework.stereotype.Service;  
import org.springframework.transaction.annotation.Transactional;

import com.ysh.simplespringdatajpatest.bean.Student;  
import com.ysh.simplespringdatajpatest.repository.StudentRepository;  
@Service  
public class StudentService \{  
  
// 注入数据访问层接口对象  
@Resource  
private StudentRepository studentRepository;  
  
@Transactional  
public void saveAll(List<Student> students) \{  
studentRepository.saveAll(students);  
\}

public Student getStuByName(String name) \{  
return studentRepository.findByName(name);  
\}  
  
public List<Student> getStusByNameAndAddress(String name,String address) \{  
return studentRepository.findByNameAndAddress(name,address);  
\}  
  
public List<Student> getStusByNameLike(String name) \{  
return studentRepository.findByNameLike("%"+name+"%");  
\}  
\}

⑥**定义控制器类**

在controller包下新建控制器类，命名StudentController

package com.ysh.simplespringdatajpatest.controller;

import java.util.ArrayList;  
import java.util.List;  
import javax.annotation.Resource;

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

import com.ysh.simplespringdatajpatest.bean.Student;  
import com.ysh.simplespringdatajpatest.service.StudentService;

@RestController  
@RequestMapping("/student")  
public class StudentController \{  
  
// 注入StudentService  
@Resource  
private StudentService studentService;  
  
@RequestMapping("/save")  
public String save() \{  
Student swk = new Student();  
swk.setAddress("广州");  
swk.setName("孙悟空");  
swk.setAge(700);  
swk.setSex('男');  
  
Student zzj = new Student();  
zzj.setAddress("广州");  
zzj.setName("蜘蛛精");  
zzj.setAge(700);  
zzj.setSex('女');  
  
Student nmw = new Student();  
nmw.setAddress("广州");  
nmw.setName("牛魔王");  
nmw.setAge(500);  
nmw.setSex('男');  
  
List<Student> students = new ArrayList<>();  
students.add(swk);  
students.add(zzj);  
students.add(nmw);  
  
studentService.saveAll(students);  
return "保存学生对象成功";  
\}  
  
@RequestMapping("/name")  
public Student getByName(String name) \{  
return studentService.getStuByName(name);  
\}  
  
@RequestMapping("/nameAndAddress")  
public List<Student> getByNameAndAddress(String name,String address) \{  
return studentService.getStusByNameAndAddress(name, address);  
\}  
  
@RequestMapping("/nameLike")  
public List<Student> getByNameLile(String name) \{  
return studentService.getStusByNameLike(name);  
\}  
  
\}

⑦**测试应用**

启动MySql数据库，新建数据库springdatajpa数据库

新建App.java启动类

package com.ysh.simplespringdatajpatest;

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

/\*\*  
\* @SpringBootApplication指定这是一个 spring boot的应用程序.  
\*/  
@SpringBootApplication  
public class App  
\{  
public static void main( String\[\] args )  
\{  
// SpringApplication 用于从main方法启动Spring应用的类。  
SpringApplication.run(App.class, args);  
\}  
\}

运行项目，JPA会在数据库中自动创建tb\_student表

**测试添加**

浏览器中输入：[http://localhost:8080/student/save][http_localhost_8080_student_save]

![70 1][]

查看数据库

![70 2][]

测试根据姓名查询学生:http://localhost:8080/student/name?name=孙悟空

![70 3][]

测试根据姓名和地址查询学生：

[http://localhost:8080/student/name?name][http_localhost_8080_student_name_name]=蜘蛛精&address=广州

![70 4][]

测试根据姓名模糊查询学生：[http://localhost:8080/student/nameLike?name=魔王][http_localhost_8080_student_nameLike_name]

![70 5][]

附：

项目目录

![70 6][]

项目源码下载：

[https://download.csdn.net/download/badao\_liumang\_qizhi/10549448][https_download.csdn.net_download_badao_liumang_qizhi_10549448]

[70]: https://img-blog.csdn.net/20180718174547186?watermark/2/text/aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk=/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70
[http_maven.apache.org_POM_4.0.0]: http://maven.apache.org/POM/4.0.0
[http_www.w3.org_2001_XMLSchema-instance]: http://www.w3.org/2001/XMLSchema-instance
[http_maven.apache.org_xsd_maven-4.0.0.xsd]: http://maven.apache.org/xsd/maven-4.0.0.xsd
[http_localhost_8080_student_save]: http://localhost:8080/student/save
[70 1]: https://img-blog.csdn.net/20180718174656289?watermark/2/text/aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk=/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70
[70 2]: https://img-blog.csdn.net/20180718174709789?watermark/2/text/aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk=/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70
[70 3]: https://img-blog.csdn.net/20180718174723130?watermark/2/text/aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk=/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70
[http_localhost_8080_student_name_name]: http://localhost:8080/student/name?name
[70 4]: https://img-blog.csdn.net/20180718174738210?watermark/2/text/aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk=/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70
[http_localhost_8080_student_nameLike_name]: http://localhost:8080/student/nameLike?name=%E9%AD%94%E7%8E%8B
[70 5]: https://img-blog.csdn.net/20180718174751235?watermark/2/text/aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk=/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70
[70 6]: https://img-blog.csdn.net/20180718174809904?watermark/2/text/aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk=/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70
[https_download.csdn.net_download_badao_liumang_qizhi_10549448]: https://download.csdn.net/download/badao_liumang_qizhi/10549448