JpaRepository(JPA)

JpaRepository

JpaRepository是SpringBoot Data JPA 提供的基础接口，具备基本的CRUD以及分页功能

save

save(保存一个实体类)
1 /*<S extends T> S save(S entity);*/
2 
3 @GetMapping("/Student/save")
4 public Student CRUD_save(){
5     //保存一个Student  
6     Student student = new Student("妲己","66");
7     Student res = StudentDo.save(Student);
8     return res;
9 }    

saveAll

 saveAll(保存提供的所有实体类)
 1　/*<S extents T> Iterable<S> saveAll(Iterable<S> entities)*/    
 2 @GetMapping("/Student/saveAll")
 3     public List<Student> Student_saveAll() {
 4 
 5         // 保存指定集合的实体
 6         List<Student> studentList = new ArrayList<>();
 7         studentList .add(new Customer("幻波", 21));
 8         studentList .add(new Customer("琳妮", 21));
 9         List<Student> res = StudentDo.saveAll(StudentList);
10         return res;
11     }

findbyid

findbyid(根据id查询对应实体类)

/*optional<T> findById(ID id)*/
@GetMapping("/Student/findByid")
public Student Student_findById(){
  //根据id查对应实体类
  Optional<Student> student = StudentDo.findById();
  if(student.isPeresent()){
    return Student.get();
    }          
   return null;
}

exeistsById

exeistsById(根据id查询对应实体类是否存在)

/*Boolean  existsById(ID id)*/
@GetMapping("/Student/existsByid")
public Blooean Student_findById(){
  //根据id查对应实体类
  return  StudentDo.existsById();
 
}

findAll

findAll(查询所有实体类)

/*Iterable<T> findAll*/
@GetMapping(/Student/findAll)
public List<Student> Student_findAll(){
  List<Student> list  = StudentDo.findAll();
  return list;   
}

findAllById

findAllById（根据给的id查询实体类集合）

/*Iterable<T> findAllById(Iterable<ID> ids)*/

@GetMapping(/Student/findAllById)
public List<Student> findAllById(String ids){
  List idList=ids.split(",").asList();
  List<Student>   studentList = idList.findAllById(idlist);
  return stduentList;  
}

count

count(统计现存实体类个数)

/*long count()*/

@GetMapping("/Student/Count")
public Long getCount(){
    //统计现存的实体个数
    return studentDo.count();
}

deleteById

/*根据id删除对用实体*/
@GetMapping("/Studebt/deleteById")
public void deleteStudent(Sring id){
  StudentDo.deleteById(666);  
}

delete　　

/*void delete(T entity)删除给定实体类*/

@GetMapping("/Student/deleteByEntity")
public void deleteByEntity(){

  Student student = new Student("laogao","23");
  StudentDo.delete(student)    
}

deleteAll

deleteAll（删除给定实体类集合）

/*deleteAll(Iterable<? extends T> entities)*/

@GetMapping("/Student/deleteAll")
public void Student_deleteAll(){
  List<Student> studentList = new ArrayList<>();
  Student Student01=new Student("A01","20");
  Student Student02=new Student("A02","30");
  studentList.add(student01);
  studentList.add(student02);
  StudentDo.deleteAll(studentList)    
      
}

findAll(Sort sort)　

findAll（查询All并根据sort排序）

/*Iterable<T> findAll(Short short) */
@GetMapping("/student/studentFindAll")
Public List<Student> findAllStudent(){
  Sory sort= new Sort(Sott.Dirextion.DESC,"age");
  List<Student> list = StduentDo.fidnAll(sort);
    returun list;
}

findAll(Pageanle pageable)

findAll（过滤查询)

　　@GetMapping("/Student/findAll)
    public void findAll_pageable() {

        // 分页查询
        // PageRequest.of 的第一个参数表示第几页（注意：第一页从序号0开始），第二个参数表示每页的大小
        Pageable pageable = PageRequest.of(1, 5); //查第二页
        Page<Customer> page = customerRepository.findAll(pageable);

        System.out.println("查询总页数:" + page.getTotalPages());
        System.out.println("查询总记录数:" + page.getTotalElements());
        System.out.println("查询当前第几页:" + (page.getNumber() + 1));
        System.out.println("查询当前页面的集合:" + page.getContent());
        System.out.println("查询当前页面的记录数:" + page.getNumberOfElements());
    }

　　

*编辑删除注意

-- @Transactional 开启事务
-- @Modifying 识别执行更新操作
-- @Query() SQL语句

原生查询

@Query(value = "select name,author,price from Book b where b.name like %:name%")
List<Book> findByNameMatch(@Param("name") String name);

编辑

@Transactional
@Modifying
@Query("update ShopCoupon sc set sc.deleted = true where sc.id in :ids")
public void deleteByIds(@Param(value = "ids") List<String> ids);

　　

三个主注解缺一不可！！