spring boot 系列之四:spring boot 整合JPA

上一篇我们讲了spring boot 整合JdbcTemplate来进行数据的持久化,

这篇我们来说下怎么通过spring boot 整合JPA来实现数据的持久化。

一、代码实现 

  1. 修改pom,引入依赖
      <!-- 引入jpa 依赖 -->
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-data-jpa</artifactId>
            </dependency>
  2. 修改application.properties,配置相关信息
    #修改tomcat默认端口号
    server.port=8090
    #修改context path
    server.context-path=/test
    
    #配置数据源信息
    spring.datasource.driver-class-name=com.mysql.jdbc.Driver
    spring.datasource.url=jdbc:mysql://localhost:3306/test
    spring.datasource.username=root
    spring.datasource.password=root
    #配置jpa
    spring.jpa.hibernate.ddl-auto=update
    spring.jpa.show-sql=true
    spring.jackson.serialization.indent_output=true
  3. 创建实体类
    package com.study.entity;
    
    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.AUTO)
        private Integer id;
        private String userName;
        private String password;
    
        public Integer getId() {
            return id;
        }
    
        public void setId(Integer id) {
            this.id = id;
        }
    
        public String getUserName() {
            return userName;
        }
    
        public void setUserName(String userName) {
            this.userName = userName;
        }
    
        public String getPassword() {
            return password;
        }
    
        public void setPassword(String password) {
            this.password = password;
        }
    
    }
  4. 创建repository接口并继承CrudRepository
    package com.study.repository;
    
    import org.springframework.data.jpa.repository.Query;
    import org.springframework.data.repository.CrudRepository;
    import org.springframework.data.repository.query.Param;
    
    import com.study.entity.User;
    
    /**
     * 注意:
     * 1.这里这里是interface,不是class
     * 
     * 2.CrudRepository里面的泛型,第一个是实体类,第二个是主键的类型
     * 
     * 3.由于crudRepository 里面已经有一些接口了,如deleteAll,findOne等, 我们直接调用即可
     * 
     * 4.当然,我们也可以根据自己的情况来实现自己的接口,如下面的getUser()方法,jpql语句和hql语句差不多
     * 
     * */
    public interface UserRepository extends CrudRepository<User, Integer> {
    
        /**
         * 我们这里只需要写接口,不需要写实现,spring boot会帮忙自动实现
         * 
         * */
        
        @Query("from User where id =:id ")
        public User getUser(@Param("id") Integer id);
    }
  5. 创建service
    1. 接口
      package com.study.service;
      
      import com.study.entity.User;
      
      
      public interface UserService {
          public User getUser(Integer id);
      }
    2. 实现
      package com.study.service.impl;
      
      import org.springframework.beans.factory.annotation.Autowired;
      import org.springframework.stereotype.Service;
      
      import com.study.entity.User;
      import com.study.repository.UserRepository;
      import com.study.service.UserService;
      
      @Service
      public class UserServiceImpl implements UserService {
      
          @Autowired
          UserRepository repository;
          
          @Override
          public User getUser(Integer id) {
              //有两种方式:
              //1.调用crudRepository的接口
      //        return repository.findOne(id);
              //2.调用我们自己写的接口
              return repository.getUser(id);
          }
      
          
      }
  6. 创建controller
    package com.study.controller;
    
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.web.bind.annotation.PathVariable;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.RestController;
    
    import com.study.entity.User;
    import com.study.service.UserService;
    
    @RestController
    public class UserController {
        @Autowired
        UserService service;
        
        @RequestMapping("/getUser/{id}")
        public User getUser(@PathVariable("id") Integer id){
            
            return service.getUser(id);
        }
    }
  7. 测试,页面以json格式显示数据库值

    

二、知识点引申

关于Repository知识点,可以去看下下面这篇文章

https://segmentfault.com/a/1190000012346333

 

posted @ 2018-04-13 12:28 JAVA开发老菜鸟 阅读(...) 评论(...) 编辑 收藏