创建项目
idea搭建环境,创建一个Spring initializr的项目。
引入依赖
pom.xml文件依赖
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-jpa</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.projectlombok</groupId>
<artifactId>lombok</artifactId>
<optional>true</optional>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
<exclusions>
<exclusion>
<groupId>org.junit.vintage</groupId>
<artifactId>junit-vintage-engine</artifactId>
</exclusion>
</exclusions>
</dependency>
<!-- druid数据库连接池-->
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>druid</artifactId>
<version>1.1.10</version>
</dependency>
application.properties文件配置
#数据源配置
spring.datasource.type=com.alibaba.druid.pool.DruidDataSource
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
#在下面3306配置自己的数据库(自己配置)
spring.datasource.url=jdbc:mysql://192.168.113.49:3306/book-test
#数据库用户(自己配置)
spring.datasource.username=dev1
#数据库密码(自己配置)
spring.datasource.password=123456
spring.datasource.initialSize=20
spring.datasource.minIdle=50
spring.datasource.maxActive=500
#上下文配置
server.port=8888
#server.servlet.context-path=/stu
#配置jpa
#帮我们自动生成表结构
spring.jpa.properties.hibernate.hbm2ddl.auto=update
#spring.jpa.properties.hibernate.dialect=org.hibernate.dialect.MySQL5InnoDBDialect
spring.jpa.show-sql= true
#spring.jpa.properties.hibernate.enable_lazy_load_no_trans=true
spring.jpa.properties.hibernate.show_sql=false
后台源码及系统结构
UserController
```java
package com.stu.demostu.controller;
import com.stu.demostu.entity.User;
import com.stu.demostu.service.UserService;
import com.stu.demostu.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.domain.Page;
import org.springframework.web.bind.annotation.*;
import javax.servlet.http.HttpServletResponse;
import java.util.List;
import java.util.Map;
@RestController
@RequestMapping("/u")
public class UserController {
@Autowired //@Autowired 是一个注释,它可以对类成员变量、方法及构造函数进行标注,让 spring 完成 bean 自动装配的工作。
private UserService userService;
@RequestMapping(value = "queryAll")
public List<User> findAll(){
List<User> s = userService.findAll();
return s;
}
/* 添加学生
* @param User 要添加的学生对象
* @return*/
@PostMapping("/add") //@postMapping = @requestMapping(method = RequestMethod.POST)
public User save(User User){
return userService.save(User);
}
/*
* 修改学生
* @param User
* @return*/
@PostMapping("/update")
public User update(User User){
return userService.save(User);
}
/*
* 删除学生
* @param id 要删除的学生id
* @return*/
@GetMapping("/del/{id}")
public String del(@PathVariable int id){ //@PathVariable 将请求URL中的模板变量映射到接口方法的参数上
userService.delete(id);
return "yes";
}
/*
* 通过姓名找到信息
* @param name
* @return*/
@GetMapping("/findByName/{name}")
public List<User> findByName(@PathVariable String name){
return userService.findStuByName(name);
}
// /*
// * 利用分页查找全部信息
// * @param page
// * @param response
// * @return
@GetMapping("/query")
public Page<User> findByPage(Integer page, HttpServletResponse response){
//异步请求使用
response.setHeader("Access-Control-Allow-Origin","*");
if(page==null || page<=0){
page = 0;
}else{
page -= 1;
}
return userService.findAll(page,5);
}
@RequestMapping("/findaaa")
public List<User> findaaa(){
return userService.findaaa();
}
@RequestMapping("/findbbb")
public List<Map> findbbb(){
return userService.findbbb();
}
@RequestMapping("/findc")
public List<Map> findc(int id){
return userService.findc(id);
}
}
UserService
package com.stu.demostu.service;
import com.stu.demostu.entity.User;
import org.springframework.data.domain.Page;
import java.util.List;
import java.util.Map;
public interface UserService {
List<User> findAll(); //UserService定义一个findAll()方法
User save(User user);
User update(User User);
void delete(Integer sid);
User findStuById(Integer id);
List<User> findStuByName(String name);
List<User> findaaa();
List<Map> findbbb();
// *//**//**
// * 分页查询所有数据
// * @param page 当前页
// * @param pageSize 每页记录数
// * @return
// *//**//*
Page<User> findAll(int page, int pageSize);
List<Map> findc(int id);
}
UserServiceImpl
package com.stu.demostu.service;
import com.stu.demostu.dao.UserDao;
import com.stu.demostu.dao.UserDao;
import com.stu.demostu.entity.User;
import com.stu.demostu.entity.User;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.domain.Page;
import org.springframework.data.domain.PageRequest;
import org.springframework.data.domain.Pageable;
import org.springframework.stereotype.Service;
import java.util.List;
import java.util.Map;
@Service
public class UserServiceImpl implements UserService {
@Autowired
private UserDao userDao;
public List<User> findAll(){
System.out.println("service---------------------");
List<User> all = userDao.findAll();
return all;
}
@Override
public User save(User User) {
return userDao.save(User);
}
@Override
public User update(User User) {
return userDao.save(User);//调用save如果传入的id已经存在那么会把之前的信息进行覆盖。
}
@Override
public void delete(Integer sid) {
userDao.deleteById(sid);
}
@Override
public User findStuById(Integer sid) {
return userDao.findUserById(sid);
}
@Override
public List<User> findStuByName(String name) {
return userDao.findStuByName(name);
}
@Override
public List<User> findaaa() {
return userDao.findaaa();
}
@Override
public List<Map> findbbb() {
return userDao.findbbb();
}
@Override
public List<Map> findc(int id) {
return userDao.findc(id);
}
@Override
public Page<User> findAll(int page, int pageSize) {
Pageable pageable = PageRequest.of(page,pageSize);
return userDao.findAll(pageable);
}
}
User
package com.stu.demostu.entity;
import lombok.Data;
import javax.persistence.*;
@Entity //表明实体类,有了这个注解,就不用再自己去写SQL创建表了,SpringBoot会自动扫描带有这个注解的类,然后通过对象关系映射,自动帮我们创建表。
@Table(name="t_user") //@Table注解用来说明该实体类对应的表和数据库,其中name =“xxx",用来表示数据表的名字
@Data //@Data注解是lambda的注解,用来节省代码开发的,不是JPA中的注解
public class User {
@Id //@Id注解表名是表的自增主键,一个实体里只能有一个
@GeneratedValue(strategy = GenerationType.IDENTITY) //设置为自动递增 @GeneratedValue(strategy = GenerationType.IDENTITY)指定自增主键
// 的自增策略,GenerationType有四个值:TABLE、SEQUENCE、IDENTITY、AUTO,我们常用的是后两种,一般mysql数据库使用SEQUENCE,AUTO的话是让JPA自己
// 选择合适的策略,默认的策略就是AUTO
// @OneToMany(cascade = CascadeType.ALL, fetch = FetchType.EAGER)
// @JoinColumn(name = "user_id")
@Column(name = "id") //@Column注解,该注解定义属性对应数据库的列名,以及是否为空等的限制
private int id;
@Column(name = "name")
private String name;
@Column(name = "sex")
private String sex;
@Column(name = "age")
private int age;
// @ManyToOne(fetch = FetchType.EAGER)
// @JoinColumn(name = "stu_name")
@Column(name = "stu_name")
private String stu_name;
public User() {
}
}
UserDao
package com.stu.demostu.dao;
import com.stu.demostu.entity.User;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.JpaSpecificationExecutor;
import org.springframework.data.jpa.repository.Query;
import org.springframework.data.repository.query.Param;
import org.springframework.stereotype.Repository;
import java.util.List;
import java.util.Map;
@Repository
public interface UserDao extends JpaRepository<User, Integer>, JpaSpecificationExecutor<User> {
User findUserById(Integer id);
@Query(name = "findStuByName", nativeQuery = true, value = "select * from t_user where name=:name")
List<User> findStuByName(@Param("name") String name);
String s = "select t1.id user_id,t1.name user_name,t1.sex user_sex,t1.age user_age,t3.id stu_id,t3.name stu_name,t3.sex stu_sex,t3.age stu_age " +
"from t_user t1 join t_su t2 on t1.id = t2.user_id " +
"join t_stu t3 on t2.stu_id = t3.id";
@Query(name = "findaaa", nativeQuery = true, value = "select * from t_user u join t_stu s on u.stu_name=s.name")
List<User> findaaa();
@Query(name = "findbbb", nativeQuery = true, value = s)
List<Map> findbbb();
@Query(name = "findc", nativeQuery = true, value = "select t1.id user_id,t1.name user_name,t1.sex user_sex,t1.age user_age,t3.id stu_id,t3.name stu_name,t3.sex stu_sex,t3.age stu_age " +
"from t_user t1 join t_su t2 on t1.id = t2.user_id " +
"join t_stu t3 on t2.stu_id = t3.id where t1.id = :id" )
List<Map> findc(@Param("id") int id);
// t_user u join t_stu s where u.stu_name=s.name
}
数据库
这里没有写前端页面,在postman中进行测试