Spring Boots：分页错误（表中许多页面为空）

Question

我的分页有问题，我有 9 个项目，所以会有两页，因为每页上的分页是 5，但是，当表格为空时，我意识到有不止一页，因为应该只有1 页，因为没有记录。该代码有效，但它给了我这个错误

• ProductDAO.java

package com.springboot3.sb3hxh.DAO;

import com.springboot3.sb3hxh.Entity.*;

import java.util.*;

public interface ProductDAO {

    List<ProductEntity> indexPagination(int page, int size);
    int totalProducts();

}

• ProductServe.java

package com.springboot3.sb3hxh.Service;

import com.springboot3.sb3hxh.DAO.*;
import com.springboot3.sb3hxh.Entity.*;
import jakarta.persistence.*;
import jakarta.transaction.*;
import org.springframework.stereotype.*;

import java.time.*;
import java.util.*;

@Service
public class ProductService implements ProductDAO {

    @PersistenceContext
    private EntityManager entityManager;

    public ProductService(EntityManager theEntityManager) {
        this.entityManager = theEntityManager;
    }

    @Override
    public List<ProductEntity> indexPagination(int page, int size) {
        TypedQuery<ProductEntity> query = entityManager.createQuery("SELECT p FROM ProductEntity p " +
                "WHERE p.deleted_at IS NULL " +
                "ORDER BY p.id ASC", ProductEntity.class);
        query.setFirstResult(page * size);
        query.setMaxResults(size);
        return query.getResultList();
    }


    @Override
    public int totalProducts() {
        TypedQuery<Long> query = entityManager.createQuery("SELECT COUNT(p) FROM ProductEntity p", Long.class);
        return query.getSingleResult().intValue();
    }

}

• ProductController.php

package com.springboot3.sb3hxh.Controller;

import com.springboot3.sb3hxh.Entity.*;
import com.springboot3.sb3hxh.Service.*;
import jakarta.validation.*;
import org.springframework.stereotype.*;
import org.springframework.ui.*;
import org.springframework.validation.*;
import org.springframework.web.bind.annotation.*;

import java.util.*;

@Controller
@RequestMapping("/products")
public class ProductController {

    private ProductService productService;

    public ProductController(ProductService theProductService){
        productService = theProductService;
    }

    @GetMapping("/list")
    public String listProducts(Model model, @RequestParam(defaultValue = "1") int page, @RequestParam(defaultValue = "5") int size){
        List<ProductEntity> ProductEntity = productService.indexPagination(page -1, size);
        int totalItems = productService.totalProducts();
        int totalPages = (int) Math.ceil((double) totalItems / size);
        model.addAttribute("currentPage", page);
        model.addAttribute("totalPages", totalPages);
        model.addAttribute("products", productEntity);
        return "/product/list-products";
    }

} 

• list-hunters.html

     <div class="pagination justify-content-center">
        <ul class="pagination">
            <li class="page-item" th:each="i: ${#numbers.sequence(1, totalPages)}" th:class="${currentPage == i} ? 'active' : ''">
                <a class="page-link" th:href="@{'/products/list?page=' + ${i}}">[[${i}]]</a>
            </li>
        </ul>
    </div>

Answer 1

我不知道你的代码中错误的确切原因，但是你有什么理由不使用Page，Pageable与JPA吗？ 使用它们，您可以在 JPA 级别轻松获取页面，而无需查询或页面索引。 我制作了一个带有分页功能的 Spring 服务器，只需引入一些 Class 或 Interace 实现，这并不难。 （如果你工作的公司开发环境是不允许使用我推荐的，那很抱歉）

页面（https://docs.spring.io/spring-data/commons/docs/current/api/org/springframework/data/domain/Page.html），可分页（https://docs.spring .io/spring-data/commons/docs/current/api/org/springframework/data/domain/Pageable.html）