SpringBoot学习记录（十一）-------- Spring Boot集成Jpa

蔚落 2021-11-17 02:42 386阅读 0赞

最近在某项目中用到了关系型数据库mysql的增删改查操作，在查询操作中遇到了一些问题，因为这个本来不是难，或者说这个技术已经在大脑中形成了清晰的操作思想，但是在这次的使用中出了些未知的问题，本想通过查询用户名来判断这个用户名是否在数据库中存在，但是后台总是报错，所以就好好研究了一下JPA，现在问题已经解决，以下是详细的项目结构和源代码。

1、项目结构  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0dhb1hpUg_size_16_color_FFFFFF_t_70]  
2、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>2.1.4.RELEASE</version>
    		<relativePath/> 
    	</parent>
    	<groupId>com.wyq</groupId>
    	<artifactId>jpa</artifactId>
    	<version>0.0.1-SNAPSHOT</version>
    	<name>jpa</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-thymeleaf</artifactId>
    		</dependency>
    		<dependency>
    			<groupId>org.springframework.boot</groupId>
    			<artifactId>spring-boot-starter-web</artifactId>
    		</dependency>
    
    		<dependency>
    			<groupId>mysql</groupId>
    			<artifactId>mysql-connector-java</artifactId>
    			<scope>runtime</scope>
    		</dependency>
    		<dependency>
    			<groupId>org.springframework.boot</groupId>
    			<artifactId>spring-boot-starter-test</artifactId>
    			<scope>test</scope>
    		</dependency>
    	</dependencies>
    
    	<build>
    		<plugins>
    			<plugin>
    				<groupId>org.springframework.boot</groupId>
    				<artifactId>spring-boot-maven-plugin</artifactId>
    			</plugin>
    		</plugins>
    	</build>
    
    </project>

3、application.properties

#连接mysql数据库
    spring.datasource.url=jdbc:mysql://localhost:3306/test?useSSL=false&characterEncoding=UTF-8&useUnicode=true&serverTimezone=GMT%2B8
    spring.datasource.username=root
    spring.datasource.password=123456
    spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
    server.tomcat.uri-encoding=UTF-8
     
    #JPA Configuration:
    spring.jpa.database=mysql
    spring.jpa.show-sql=true  
    spring.jpa.generate-ddl=true
    spring.jpa.hibernate.ddl-auto=update
    spring.jpa.database-platform=org.hibernate.dialect.MySQL5Dialect

4、User.class

package com.wyq.entity;
    
    import javax.persistence.Entity;
    import javax.persistence.GeneratedValue;
    import javax.persistence.GenerationType;
    import javax.persistence.Id;
    import javax.persistence.Table;
    
    @Entity
    @Table(name="user")
    public class User {
    
    	@Id
    	@GeneratedValue(strategy = GenerationType.AUTO)
    	private Integer id;
    	
    	private Integer age;
    	
    	private String password;
    	
    	private String username;
    	
    	private String phonenum;
    
    
    
    	public Integer getId() {
    		return id;
    	}
    
    	public void setId(Integer id) {
    		this.id = id;
    	}
    
    	public Integer getAge() {
    		return age;
    	}
    
    	public void setAge(Integer age) {
    		this.age = age;
    	}
    
    	public String getPassword() {
    		return password;
    	}
    
    	public void setPassword(String password) {
    		this.password = password;
    	}
    	
    
    	public String getUsername() {
    		return username;
    	}
    
    	public void setUsername(String username) {
    		this.username = username;
    	}
    
    	public String getPhonenum() {
    		return phonenum;
    	}
    
    	public void setPhonenum(String phonenum) {
    		this.phonenum = phonenum;
    	}
    
    	public User() {}
    	
    	public User(int id,int age,String username,String password,String phonenum) {
    		this.id = id;
    		this.age = age;
    		this.username = username;
    		this.password = password;
    		this.phonenum = phonenum;
    	}
    	
    }

5、UserRepository.class

package com.wyq.repository;
    
    import java.util.List;
    
    import org.springframework.data.jpa.repository.JpaRepository;
    
    import com.wyq.entity.User;
    
    public interface UserRepository extends JpaRepository<User, Integer>{
    
    	public List<User>  findByUsername(String username);
    }

6、UserService.class

package com.wyq.service;
    
    import java.util.List;
    
    import com.wyq.entity.User;
    
    public interface UserService {
    
    	public List<User>  findByUsername(String username);
    	
    }

7、UserServiceImpl.class

package com.wyq.impl;
    
    import java.util.List;
    
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.stereotype.Service;
    
    import com.wyq.entity.User;
    import com.wyq.repository.UserRepository;
    import com.wyq.service.UserService;
    
    @Service("UserService")
    public class UserServiceImpl implements UserService{
    
    	@Autowired
    	private UserRepository userRepository;
    	
    	@Override
    	public List<User> findByUsername(String username) {
    		// TODO Auto-generated method stub
    		return this.userRepository.findByUsername(username);
    	}
    }

8、JpaApplicationTests.class(测试类)

package com.wyq;
    
    import java.util.List;
    
    import org.junit.Test;
    import org.junit.runner.RunWith;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.boot.test.context.SpringBootTest;
    import org.springframework.test.context.junit4.SpringRunner;
    
    import com.wyq.entity.User;
    import com.wyq.service.UserService;
    
    @RunWith(SpringRunner.class)
    @SpringBootTest
    public class JpaApplicationTests {
    
    	@Autowired
    	private UserService userService;
    	
    	@Test
    	public void contextLoads() {
    		System.out.println("测试程序");
    	}
    	
    	@Test 
    	public void jpaTest() {
    		
    		List<User> testList = this.userService.findByUsername("test");
    		
    		System.out.println("测试成功"+testList.size());
    	}
    
    }

9、需要在test数据库中新建user表，表的字段如图所示。  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0dhb1hpUg_size_16_color_FFFFFF_t_70 1]  
10、测试结果。  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0dhb1hpUg_size_16_color_FFFFFF_t_70 2]源码地址：https://github.com/lovsw/Spring-Boot-Study  
如有问题，欢迎加入Spring Boot学习交流群： 891457028，进行沟通。

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