Spring-data-jpa 笔记（一）

Spring Data JPA简介：

可以理解为 JPA 规范的再次封装抽象，底层还是使用了 Hibernate 的 JPA 技术实现，引用 JPQL（Java Persistence Query Language）查询语言，属于 Spring 的整个生态体系的一部分。

优势：

属于 Spring 的整个生态体系的一部分上手简单、开发效率高，ORM提供的能力他都提供，ORM框架没有提供的业务逻辑功能Spring-data-jpa也提供，全方位的解决用户的需求。使用Spring-data-jpa进行开发的过程中，常用的功能，我们几乎不需要写一条sql语句。

Spring Data操作主要特性：

提供模板操作，如 Spring Data Redis 和 Spring Data Riak；

强大的 Repository 和定制的数据储存对象的抽象映射；

对数据访问对象的支持（Auting 等）。

Spring Data JPA 的主要类及结构图:

七个大 Repository 接口：

Repository（org.springframework.data.repository）；

CrudRepository（org.springframework.data.repository）；

PagingAndSortingRepository（org.springframework.data.repository）；

JpaRepository（org.springframework.data.jpa.repository）；

QueryByExampleExecutor（org.springframework.data.repository.query）；

JpaSpecificationExecutor（org.springframework.data.jpa.repository）；

QueryDslPredicateExecutor（org.springframework.data.querydsl）。

两大 Repository 实现类：

SimpleJpaRepository（org.springframework.data.jpa.repository.support）；

QueryDslJpaRepository（org.springframework.data.jpa.repository.support）。

Quick start:

以spring-boot2.1.3 ,mysql5.5+ 为技术场景

开发环境：

SPRING STS，MAVEN3.0+,JDK1.8

1、创建sringboot工程

完整工程结构图如下：

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>2.1.3.RELEASE</version>
         <relativePath /> <!-- lookup parent from repository -->
     </parent>
     <groupId>com.zhengjiang</groupId>
     <artifactId>springboot-demo</artifactId>
     <version>0.0.1-SNAPSHOT</version>
     <name>springboot-demo</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-web</artifactId>
         </dependency>

         <dependency>
             <groupId>org.springframework.boot</groupId>
             <artifactId>spring-boot-starter-test</artifactId>
             <scope>test</scope>
         </dependency>

         <dependency>
             <groupId>org.springframework.boot</groupId>
             <artifactId>spring-boot-devtools</artifactId>
             <optional>true</optional>
         </dependency>

         <dependency>
             <groupId>org.springframework.boot</groupId>
             <artifactId>spring-boot-starter-data-jpa</artifactId>
         </dependency>

         <dependency>
             <groupId>mysql</groupId>
             <artifactId>mysql-connector-java</artifactId>
             <version>6.0.6</version>
         </dependency>

         <dependency>
             <groupId>com.alibaba</groupId>
             <artifactId>druid-spring-boot-starter</artifactId>
             <version>1.1.6</version>
         </dependency>
         <!-- import lombok -->
         <dependency>
             <groupId>org.projectlombok</groupId>
             <artifactId>lombok</artifactId>
             <scope>provided</scope>
         </dependency>
     </dependencies>

     <build>
         <plugins>
             <plugin>
                 <groupId>org.springframework.boot</groupId>
                 <artifactId>spring-boot-maven-plugin</artifactId>
                 <configuration>
                     <fork>true</fork>
                 </configuration>
             </plugin>
         </plugins>
     </build>

 </project>

2、修改application.properties 为yml配置

 spring:
   profiles:
     active: product
   datasource:
     driver-class-name: com.mysql.jdbc.Driver
     url: jdbc:mysql://localhost:3306/test?useUnicode=true&characterEncoding=utf-8&useSSL=true&serverTimezone=UTC
     username: root
     password:
   jpa:
     hibernate:
       ddl-auto: update
     show-sql: true
   jackson:
     date-format: yyyy-MM-dd HH:mm:ss
     time-zone: UTC

创建实体类UserInfo：

 package com.zhengjiang.springboot.demo.entity;

 import java.util.Date;

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

 import org.springframework.stereotype.Component;

 import com.fasterxml.jackson.annotation.JsonIgnoreProperties;

 import lombok.Data;
 import lombok.ToString;

 @Data
 @ToString
 @Entity
 @Table(name = "t_sys_user")
 @Component
 @JsonIgnoreProperties(value = { "hibernateLazyInitializer", "handler" })
 public class UserInfo{

     public UserInfo() {}

     public UserInfo(String name) {this.name = name;}
     @Id
     @GeneratedValue
     private  Long id; //ID
     private  String name; //姓名
     private  String jobNumber; //工号
     private Date createTime; //创建时间
 }

创建一个 Repository

 package com.zhengjiang.springboot.demo.respository;

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

 import com.zhengjiang.springboot.demo.entity.UserInfo;

 public interface UserRepository extends JpaRepository<UserInfo, Long>,JpaSpecificationExecutor<UserInfo> {
     UserInfo findByName(String name);
 }

创建service 以及实现类

 package com.zhengjiang.springboot.demo.service;

 import java.util.List;

 import org.springframework.data.domain.Page;

 import com.zhengjiang.springboot.demo.entity.UserInfo;

 public interface UserService {

     UserInfo findById(Long id);
     List<UserInfo> getUserList();
     UserInfo getUserByName(String name);
     UserInfo addUserInfo(UserInfo userInfo);
     UserInfo updateUserInfoById(UserInfo userInfo);
     void deleteUserInfoById(Long Id);
     List<UserInfo>getCurrentUserList();
     Page<UserInfo> getPageUserList();
 }

 package com.zhengjiang.springboot.demo.service.impl;

 import java.util.List;

 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.data.domain.Page;
 import org.springframework.data.domain.Sort;
 import org.springframework.stereotype.Service;
 import org.springframework.data.domain.PageRequest;

 import com.zhengjiang.springboot.demo.entity.UserInfo;
 import com.zhengjiang.springboot.demo.respository.UserRepository;
 import com.zhengjiang.springboot.demo.service.UserService;

 @Service
 public class UserServiceImpl implements UserService {
     @Autowired
     private UserRepository userRepository;

     @Override
     public UserInfo findById(Long id) {
         return userRepository.getOne(id);
     }
     @Override
     public List<UserInfo> getUserList() {
         return userRepository.findAll();
     }

     @Override
     public UserInfo getUserByName(String name) {
         UserInfo userInfo = userRepository.findByName(name);
         return userInfo;
     }

     @Override
     public UserInfo addUserInfo(UserInfo userInfo) {
         return userRepository.save(userInfo);
     }

     @Override
     public UserInfo updateUserInfoById(UserInfo userInfo) {
         return userRepository.save(userInfo);
     }

     @Override
     public void deleteUserInfoById(Long id) {
         userRepository.deleteById(id);
     }

     @Override
     public List<UserInfo> getCurrentUserList() {
         Sort sort=new Sort(Sort.Direction.DESC,"createTime");
         return userRepository.findAll(sort);
     }
     @Override
     public Page<UserInfo> getPageUserList() {
         Sort sort=new Sort(Sort.Direction.DESC,"createTime");
         PageRequest pageable=new PageRequest(0,5,sort);
         userRepository.findAll(pageable);
         return userRepository.findAll(pageable);
     }
 }

创建controller

 package com.zhengjiang.springboot.demo.controller;

 import java.text.SimpleDateFormat;
 import java.util.Date;
 import java.util.List;
 import java.util.TimeZone;

 import javax.servlet.http.HttpServletRequest;

 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.beans.propertyeditors.CustomDateEditor;
 import org.springframework.data.domain.Page;
 import org.springframework.web.bind.ServletRequestDataBinder;
 import org.springframework.web.bind.annotation.GetMapping;
 import org.springframework.web.bind.annotation.InitBinder;
 import org.springframework.web.bind.annotation.PostMapping;
 import org.springframework.web.bind.annotation.PutMapping;
 import org.springframework.web.bind.annotation.RequestMapping;
 import org.springframework.web.bind.annotation.RequestParam;
 import org.springframework.web.bind.annotation.RestController;
 import com.zhengjiang.springboot.demo.entity.UserInfo;
 import com.zhengjiang.springboot.demo.service.UserService;

 @RestController
 @RequestMapping("/test")
 public class TestController {

         @Autowired
         private UserService userService;

         /**
          *
          * @param id
          * @return
          */
         @GetMapping(value = "/getOne")
         public UserInfo getOne(@RequestParam("id") Long id) {
             return userService.findById(id);
         }

         /**
          * 获取所有用户
          * @return
          */
         @GetMapping(value = "/getUserList")
         public List<UserInfo> getUserList() {
             return userService.getUserList();
         }

         /**
          * 根据用户名查找
          * @param name
          * @return
          */
         @GetMapping(value = "/getUserInfo")
         public UserInfo getUserInfoByName(@RequestParam("name") String name) {
             UserInfo u = userService.getUserByName(name);
             return u;
         }

         /**
          * 根据createTime倒序查询
          * @return
          */
         @GetMapping(value = "/getCurrentUserList")
         public List<UserInfo> getCurrentUserList(){
             return userService.getCurrentUserList();
         }

         /**
          * 分页查找
          * @return
          */
         @GetMapping(value="/getPageUserList")
         public Page<UserInfo> getPageUserList(){
             return userService.getPageUserList();
         }

         /**
          * 添加用户
          * @param userInfo
          * @return
          */
         @PostMapping(value = "/addUserInfo")
         public UserInfo addUserInfo(UserInfo userInfo) {
             return userService.addUserInfo(userInfo);
         }

         /**
          * 更新用户
          * @param userInfo
          * @return
          */
         @PostMapping(value ="/updateUserInfo")
         public UserInfo updateUserInfo(UserInfo userInfo){
             return userService.updateUserInfoById(userInfo);
         }

         /**
          * 删除用户
          * @param id
          */
         @PostMapping(value="/deleteUserInfo")
         public void deleteUserInfo(@RequestParam("id") Long id){
              userService.deleteUserInfoById(id);
         }

         @InitBinder
         protected void init(HttpServletRequest request, ServletRequestDataBinder binder) {
             SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
             dateFormat.setTimeZone(TimeZone.getTimeZone("UTC"));/*TimeZone时区，解决差8小时的问题*/
             binder.registerCustomEditor(Date.class, new CustomDateEditor(dateFormat, false));
         }
 }

用postman 测试接口。