CrudRepository接口访问数据

CrudRepository提供了最基本的对实体类的增、删、改、查操作。

示例：CrudRepository接口访问数据

程序清单：/jpa/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>

	<groupId>com.dwx</groupId>
	<artifactId>jpa</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<packaging>jar</packaging>

	<name>jpa</name>
	<description></description>

	<parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>2.0.5.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>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>

程序清单：/jpa/src/main/resources/application.properties

spring.datasource.url=jdbc:mysql://localhost:3306/spring_boot
spring.datasource.username=root
spring.datasource.password=root
spring.datasource.driverClassName=com.mysql.jdbc.Driver
spring.jpa.database=MySQL
spring.jpa.show-sql=true
spring.jpa.hibernate.naming-strategy=org.hibernate.cfg.ImprovedNamingStrategy
spring.jpa.properties.hibernate.dialect=org.hibernate.dialect.MySQL5Dialect

程序清单：/jpa/src/main/java/com/dwx/bean/User.java

package com.dwx.bean;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;
@Entity
@Table(name="t_user")
public class User {
	@Id
	@GeneratedValue(strategy = GenerationType.IDENTITY)
	private Integer userId;
	private String userName;
	private String sex;
	private Integer age;
	public Integer getUserId() {
		return userId;
	}
	public void setUserId(Integer userId) {
		this.userId = userId;
	}
	public String getUserName() {
		return userName;
	}
	public void setUserName(String userName) {
		this.userName = userName;
	}
	public String getSex() {
		return sex;
	}
	public void setSex(String sex) {
		this.sex = sex;
	}
	public Integer getAge() {
		return age;
	}
	public void setAge(Integer age) {
		this.age = age;
	}
}

程序清单：/jpa/src/main/java/com/dwx/repository/UserRepository.java

package com.dwx.repository;
import org.springframework.data.repository.CrudRepository;
import com.dwx.bean.User;
public interface UserRepository extends CrudRepository<User, Integer> {

}

程序清单：/jpa/src/main/java/com/dwx/service/UserService.java

package com.dwx.service;
import java.util.Optional;

import javax.annotation.Resource;
import javax.transaction.Transactional;
import org.springframework.stereotype.Service;
import com.dwx.bean.User;
import com.dwx.repository.UserRepository;
@Service
public class UserService {
	@Resource
	private UserRepository userRepository;
	@Transactional
	public User save(User user) {
		return userRepository.save(user);
	}
	
	@Transactional
	public void delete(Integer id) {
		userRepository.deleteById(id);
	}
	
	@Transactional
	public void update(User user) {
		user.setUserName("露丝");
		user.setAge(23);
	}
	
	public User getById(Integer id) {
		Optional<User> op=userRepository.findById(id);
		return op.get();
	}
	
	public Iterable<User> getAll(){
		return userRepository.findAll();
	}
}

程序清单：/jpa/src/main/java/com/dwx/controller/UserController.java

package com.dwx.controller;
import javax.annotation.Resource;

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

import com.dwx.bean.User;
import com.dwx.service.UserService;
@RestController
@RequestMapping("/user")
public class UserController {
	@Resource
	private UserService userService;
	@RequestMapping("/save")
	public String save() {
		User user=new User();
		user.setUserName("jack");
		user.setSex("男");
		user.setAge(22);
		userService.save(user);
		return "数据添加成功!";
	}
	
	@RequestMapping("/delete")
	public String delete() {
		userService.delete(2);
		return "删除成功!";
	}
		
	@RequestMapping("/update")
	public String update() {
		User user=userService.getById(2);
		userService.update(user);
		return "更新成功!";
	}
	
	@RequestMapping("/getAll")
	public Iterable<User> getAll(){
		return userService.getAll();
	}
}

启动Spring Boot项目，输入以下地址：http://localhost:8080/user/save

测试删除用户，输入以下地址：http://localhost:8080/user/delete

测试更改用户，输入以下地址：http://localhost:8080/user/update

测试查询用户，输入以下地址：http://localhost:8080/user/getAll