java – 按数组列表自定义分页

我想在java代码中创建一个数组列表的自定义分页

import org.springframework.data.domain.sort;
import org.springframework.data.domain.PageRequest;
import org.springframework.data.domain.Page;
import org.springframework.data.domain.PageImpl;
import org.springframework.data.domain.sort.Direction;
...    

    int page = 0;
    int count = 8;
    String sortOrder = "desc";
    String sortBy = "id";

    Sort sort = new Sort(Direction.fromString(sortOrder),sortBy);
    PageRequest pageable = new PageRequest(page,count,sort);

    List

上面的脚本不会返回包含8个元素的页面.为什么？

注：列表没有从db返回

你能帮助我吗？

最佳答案

我解决了这个解决方法.

    import org.springframework.data.domain.sort;
    import org.springframework.data.domain.PageRequest;
    import org.springframework.data.domain.Page;
    import org.springframework.data.domain.PageImpl;
    import org.springframework.data.domain.sort.Direction;
    ...    

        int page = 0;
        int count = 8;
        String sortOrder = "desc";
        String sortBy = "id";

        Sort sort = new Sort(Direction.fromString(sortOrder),sortBy);
        PageRequest pageable = new PageRequest(page,sort);

        List

我实现了一个新的自定义比较器类

import java.lang.reflect.Field;
import java.util.Comparator;
import java.util.Date;

public class MyListComparator implements Comparatorarator(String sortBy,String sortOrder) {
        this.sortBy = sortBy;
        this.sortOrder = sortOrder;
    }

    @Override
    public int compare(Object o1,Object o2) {

        try {
            Field field1 = o1.getClass().getDeclaredField(sortBy);
            Field field2 = o2.getClass().getDeclaredField(sortBy);

            field1.setAccessible(true); // because the fields in Impianto entity has "private" 
            field2.setAccessible(true);

            if(o1.getClass().getDeclaredField(sortBy).getType() == Long.class){
                Long d1 = (Long) field1.get(o1);
                Long d2 = (Long) field2.get(o2);
                return (sortOrder.toLowerCase().equals("asc"))? d1.compareto(d2) : d2.compareto(d1);

            }else if(o1.getClass().getDeclaredField(sortBy).getType() == Date.class){
                Date d1 = (Date) field1.get(o1);
                Date d2 = (Date) field2.get(o2);
                return (sortOrder.toLowerCase().equals("asc"))? d1.compareto(d2) : d2.compareto(d1);

            }else{
                String d1 = (String) field1.get(o1);
                String d2 = (String) field2.get(o2);
                return (sortOrder.toLowerCase().equals("asc"))? d1.compareto(d2) : d2.compareto(d1);

            }
        } catch (SecurityException e) {
            throw new RuntimeException(e);
        } catch (NoSuchFieldException e) {
            throw new RuntimeException("Missing variable sortBy");
        }catch (ClassCastException e) {
            throw new RuntimeException("sortBy is not found in class list");
        } catch (IllegalArgumentException e) {
            //shoud not happen
            throw new RuntimeException(e);
        } catch (illegalaccessexception e) {
            throw new RuntimeException(e);
        }
    }


}

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