SpringBoot如何增强PageHelper入参的健壮性

PageHelper.startPage(int pageNum, int pageSize, boolean count) 参数为外部输入，故存在异常输入场景。比如 pageNum 和 pageSize 输入的值 负数 或者 0，所以引入PageUtils来对入参进行判断矫正，从而避免引入异常。

第1步：支持配置的方式来修改默认值 page-helper: default-page-num: 1 default-page-size: 10 max-page-size: 50 count-total-or-not: true 第2步：引入PageUtils import jakarta.annotation.PostConstruct; import org.springframework.beans.factory.annotation.Value; import org.springframework.stereotype.Component; import java.util.Objects; @Component public class PageUtils { private static int defaultPageNumber; // 默认显示第几页 private static int defaultPageSize; // 默认每页显示多少条数据 private static int maxSizePage; // 每页显示条数上限 private static boolean isQueryTotalCount; // 每次查询DB时,是否进行count查询 @Value("${page-helper.default-page-num:1}") private int pageNumberFromConfig; @Value("${page-helper.default-page-size:10}") private int pageSizeFromConfig; @Value("${page-helper.max-page-size:15}") private int maxSizePerPageFromConfig; @Value("${page-helper.count-total-or-not:true}") private boolean isQueryTotalFromConfig; @PostConstruct private void init() { defaultPageNumber = pageNumberFromConfig; defaultPageSize = pageSizeFromConfig; maxSizePage = maxSizePerPageFromConfig; isQueryTotalCount = isQueryTotalFromConfig; } public static int getPageNum(Integer pageNum) { if (Objects.isNull(pageNum) || pageNum <= 0) { return defaultPageNumber; } else { return pageNum; } } public static int getPageSize(Integer pageSize) { if (Objects.isNull(pageSize) || pageSize <= 0) { return defaultPageSize; } else if (pageSize > 100) { return maxSizePage; } else { return pageSize; } } public static boolean isQueryTotalCount() { return isQueryTotalCount; } } 第3步：使用 public List<Student> listStudents(Integer pageNum, Integer PageSize) { PageHelper.startPage(PageUtils.getPageNum(pageNum), PageUtils.getPageSize(PageSize), PageUtils.isQueryTotalCount()); PageHelper.orderBy("age asc"); List<Student> students = userMapper.listStudents(); PageInfo<Student> studentPageInfo = PageInfo.of(students); return students; }

参考

@PostConstruct 的执行时机