Spring Data Jpa接口简介

Repository接口

public interface Repository<T, ID> {....}

提供了按方法名称的查询方式；

 

 

提供了@Query的查询方式

可能遇到的错误：

1）Caused by: javax.persistence.TransactionRequiredException: Executing an update/delete query（手动加@Transactional解决）

2）如果test方法里加事务注解数据不更新的话，还需要手动加@Rollback（false）解决，自己测试的时候，只加了一个@Transactional就更新成功了.

CrudRepository接口

public interface CrudRepository<T, ID> extends Repository<T, ID> {....}

    public void test1 () {
        JpaUser jpaUser = new JpaUser("名称1","地址1",10,20,2);
        Optional<JpaUser> optionalT = userRespotory.findById(1) ;
        Iterable<JpaUser> list = userRespotory.findAll();
        userRespotory.delete(jpaUser);
        userRespotory.save(jpaUser);//保存or更新

PagingAndSortingRepository接口

public interface PagingAndSortingRepository<T, ID> extends CrudRepository<T, ID> {
    Iterable<T> findAll(Sort var1);
    Page<T> findAll(Pageable var1);
}

//测试sort   

public void test1 () {
        JpaUser jpaUser = new JpaUser("名称1","地址1",10,20,100);

        Sort sort = new Sort(Sort.Direction.DESC,"id");

        Iterable<JpaUser> list = userRespotory.findAll(sort);

//测试page

    public void test1 () {
        JpaUser jpaUser = new JpaUser("名称1","地址1",10,20,100);
        Pageable pageable = PageRequest.of(0, 2);
        Page<JpaUser> page = userRespotory.findAll(pageable);

        System.out.println(page.getTotalElements());//总条数
        System.out.println(page.getTotalPages());//总页数
        System.out.println(page.getContent());//当前页集合
//测试分页+排序

    public void test1 () {
        JpaUser jpaUser = new JpaUser("名称1","地址1",10,20,100);
        Pageable pageable = PageRequest.of(1, 2,Sort.Direction.DESC,"id","age1");
        Page<JpaUser> page = userRespotory.findAll(pageable);

        System.out.println(page.getTotalElements());//总条数
        System.out.println(page.getTotalPages());//总页数
        System.out.println(page.getContent());//当前页集合

JpaRepository接口

public interface JpaRepository<T, ID> extends PagingAndSortingRepository<T, ID>, QueryByExampleExecutor<T> {....}