Spring Data JPA与Hibernate，Spring Boot集成,实战

1.build.gradle

我们需要添加Spring Data JPA及Mysql连接的驱动的依赖.Spring Boot已经提供了相关的Starter来实现Spring Data JPA开箱及用的功能,只需要在build.gradle文件中添加Spring Data JPA的starter的库即可.

dependencies {
	compile('org.springframework.boot:spring-boot-starter-web')
	//添加Spring Data JPA 的依赖
	compile('org.springframework.boot:spring-boot-starter-data-jpa')
	//添加Mysql连接驱动依赖
	compile('mysql:mysql-connector-java:6.0.5')
	
	
	testCompile('org.springframework.boot:spring-boot-starter-test')
}

spring-boot-starter-data-jpa库提供了以下依赖:hibernate,Spring Data JPA,Spring ORM

2.集成H2

Spring Boot的自动配置功能会自动检测有无指定的数据库类型.如果没有指定,Spring Boot会认为用户想要配置一个内嵌的数据库,此时会扫描classpath有相应的内嵌数据库.

dependencies {
	//....
	//添加h2依赖
	runtime('com.h2database:h2:1.4.196')
        //.....
}

其中"runtime"表明该依赖对于运行时是必要的.

3.下载安装mysql

这里不在详述,资料横多

4.实战

将在之前项目上建立,和之前的博客(Thymeleaf)相对应,之前已有代码只修改不重写了

a.User类不修改,可以直接用

b.修改用户资源接口,继承自CrudRepository

import org.springframework.data.repository.CrudRepository;


public interface UserRepository extends CrudRepository<User, Long> {

}

由于Spring Data JPA已经帮助用户做了实现,因此用户不需要做任何实现.

c.修改控制器

UserController实现的方法全部换成JPA默认实现.



import java.util.Optional;


import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.servlet.ModelAndView;

@RestController
@RequestMapping("/users")
public class UserController {

	@Autowired
	private UserRepository userRepository;
	/**
	 * 查询所有用户
	 * @param model
	 * @return
	 */
	@GetMapping
	public ModelAndView list(Model model) {
		model.addAttribute("userList",userRepository.findAll());
		model.addAttribute("title","用户管理");
		return new ModelAndView("users/list","userModel",model);	
	}
	/**
	 * 根据id查询用户
	 * @param id
	 * @param model
	 * @return
	 */
	@GetMapping("{id}")
	public ModelAndView view(@PathVariable("id") Long id,Model model) {
		Optional<User> user = userRepository.findById(id);
		model.addAttribute("user",user.get());
		model.addAttribute("title","查看用户");
		return new ModelAndView("users/view","userModel",model);
	}
	/**
	 * 获取创建表单页面
	 * @param model
	 * @return
	 */
	@GetMapping("/form")
	public ModelAndView createForm(Model model) {
		model.addAttribute("user", new User(null,null,null));
		model.addAttribute("title","创建用户");
		return new ModelAndView("users/form","userModel",model);
	}
	/**
	 * 保存或者修改用户
	 * @param user
	 * @return
	 */
	@PostMapping
	public ModelAndView saveOrUpdateUser(User user) {
		user = userRepository.save(user);
		return new ModelAndView("redirect:/users");
	}
	/**
	 * 废除用户
	 * @param id
	 * @return
	 */
	@GetMapping(value = "delete/{id}")
	public ModelAndView delete(@PathVariable("id") Long id) {
		userRepository.deleteById(id);
		return new ModelAndView("redirect:/users");
	}
	/**
	 * 获取修改用户的界面
	 * @param id
	 * @param model
	 * @return
	 */
	@GetMapping(value = "modify/{id}")
	public ModelAndView modifyForm(@PathVariable("id") Long id,Model model) {
		Optional<User> user = userRepository.findById(id);	
		model.addAttribute("user",user.get());
		model.addAttribute("title","修改用户");
		return new ModelAndView("users/form","userModel",model);
	}
	
	
	
	
}

d.创建数据库

首先创建数据库,编码为utf-8

mysql> drop database if exists xchange;
Query OK, 0 rows affected, 1 warning (0.00 sec)

mysql> create database xchange default charset utf8 collate utf8_general_ci;
Query OK, 1 row affected (0.00 sec)

修改application.properties,增加下面几项配置.

#DataSource
spring.datasource.url=jdbc:mysql://localhost/project?useSSL=false&serverTimezone=UTC&characterEncoding=utf-8
spring.datasource.username=root
spring.datasource.password=123456
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver

#JPA
spring.jpa.show-sql = true
spring.jpa.hibernate.ddl-auto=create-drop

spring.jpa.hibernate.ddl-auto=create-drop,指每次启动时,都会自动废除并创建数据库中的表,在开发时非常方便.

e.打开网页测试结束.