一、 背景
Mybatis Plus對于分頁數量大小預設有限制,同時有的時候分頁接口和導出接口通常是一模一樣,這時候需要自動判斷是否需要開啟分頁。
二、實作思路
// 當`page`參數為null時,會抛出空指針異常
<E extends IPage<T>> E selectPage(E page, @Param(Constants.WRAPPER) Wrapper<T> queryWrapper);
三、實作代碼
- 基礎分頁參數
@Data
@ToString(callSuper = true)
@EqualsAndHashCode(callSuper = true)
public class PageParam<T> extends Page<T> {
private Integer isOpenPage = 1;
}
public class BaseServiceImpl<M extends BaseSqlInjectorMapper<T>, T> extends ServiceImpl<M, T> {
public PageParam<T> selectByPage(PageParam<T> page, Wrapper<T> queryWrapper) {
if (page.getIsOpenPage() == 1) {
return getBaseMapper().selectPage(page, queryWrapper);
}
List<T> list = list(queryWrapper);
PageParam<T> pageResult = new PageParam<>();
pageResult.setRecords(list);
pageResult.setTotal(list.size());
return pageResult;
}
public <E> PageParam<E> selectByPage(PageParam<E> page, Function<PageParam<E>, List<E>> function) {
if (page.getIsOpenPage() == 1) {
List<E> records = function.apply(page);
page.setRecords(records);
return page;
}
List<E> list = function.apply(null);
PageParam<E> pageResult = new PageParam<>();
pageResult.setRecords(list);
pageResult.setTotal(list.size());
return pageResult;
}
public <E> IPage<E> selectByPage(PageParam<T> page, Wrapper<T> wrapper, Class<E> clz) {
IPage<T> eiPage = selectByPage(page, wrapper);
return eiPage.convert(o -> {
E e = null;
try {
e = clz.newInstance();
} catch (InstantiationException | IllegalAccessException ex) {
throw new RuntimeException(ex);
}
BeanUtils.copyProperties(o, e);
return e;
});
}
}
四、 優化版本
- 設定最大分頁數
@Bean
public MybatisPlusInterceptor mybatisPlusInterceptor() {
MybatisPlusInterceptor interceptor = new MybatisPlusInterceptor();
PaginationInnerInterceptor pageInterceptor = new PaginationInnerInterceptor();
// 設定最大單頁限制數量,預設 500 條,-1 不受限制
pageInterceptor.setMaxLimit(-1L);
interceptor.addInnerInterceptor(pageInterceptor);
return interceptor;
}
- 基礎分頁參數類
@Data
@ToString(callSuper = true)
@EqualsAndHashCode(callSuper = true)
public class PageParam<T> extends Page<T> {
private Integer isOpenPage = 1;
@Override
public long getSize() {
if (1 == isOpenPage) {
return super.getSize();
}
return -1;
}
@Override
public long getTotal() {
if (1 == isOpenPage) {
return super.getTotal();
}
return getRecords().size();
}
}