需求：班级与教师是多对多关系，在后台班级管理需要添加一个接口，传入教师的id和pageable,返回带分页数据的班级信息。

Page
    
      pageByTeacher(Long teacherId, Pageable pageable);
    

一开始打算是在KlassRepository（继承自PagingAndSortingRepository）中添加一个类似findByElementId的接口，然后直接返回带分页的数据。但是试了几次并不成功,无论是把teacher还是将带teacher的List传入方法中都失败。

换了一种思路，直接调TeacherRepository的FindById()方法找到teacher,然后返回teacher的成员klassList就行了。

Teacher teacher = teacherRepository.findById(teacherId).get();    List
    
      klassList = teacher.getKlassList();
    

但是光返回klassList还不行，需要将它包装成Page才行，去官网上查到了一种使用List构造Page的方法

PageImplpublic PageImpl(List
    
      content,                Pageable pageable,                long total)Constructor of PageImpl.Parameters:content - the content of this page, must not be null.pageable - the paging information, must not be null.total - the total amount of items available. The total might be adapted considering the length of the content given, if it is going to be the content of the last page. This is in place to mitigate inconsistencies.
    

参数：

一开始还以为它会自己按照传入的参数分割List

Page
    
      klassPage = new PageImpl
     
      (klassList, pageable, klassList.size());
     
    

结果debug发现不行，得手动分割，就去网上参考了别人的写法

// 当前页第一条数据在List中的位置    int start = (int)pageable.getOffset();    // 当前页最后一条数据在List中的位置       int end = (start + pageable.getPageSize()) > klassList.size() ? klassList.size() : ( start + pageable.getPageSize());    // 配置分页数据    Page
    
      klassPage = new PageImpl
     
      (klassList.subList(start, end), pageable, klassList.size());
     
    

debug查看结果

public 
    
      Page
     
       listConvertToPage(List
      
        list, Pageable pageable) {    int start = (int)pageable.getOffset();    int end = (start + pageable.getPageSize()) > list.size() ? list.size() : ( start + pageable.getPageSize());    return new PageImpl
       
        (list.subList(start, end), pageable, list.size());}