2021-08-02ssm分页功能

1.Book实体类

package com.pro.domain;

import com.baomidou.mybatisplus.annotation.IdType;
import com.baomidou.mybatisplus.annotation.TableField;
import com.baomidou.mybatisplus.annotation.TableId;
import com.baomidou.mybatisplus.annotation.TableName;

@TableName("book")
public class Book {
    @TableId(type = IdType.AUTO)
    @TableField("bookId")
    private Long bookId;
    private String bookName;
    private Long categoryId;
    private String subTitle;
    private String author;
    private String cover;
    private String description;
    private float evaluationScore;
    private Integer evaluationQuantity;

    @Override
    public String toString() {
        return "Book{" +
                "bookId=" + bookId +
                ", bookName='" + bookName + '\'' +
                ", categoryId=" + categoryId +
                ", subTitle='" + subTitle + '\'' +
                ", author='" + author + '\'' +
                ", cover='" + cover + '\'' +
                ", description='" + description + '\'' +
                ", evaluationScore=" + evaluationScore +
                ", evaluationQuantity=" + evaluationQuantity +
                '}';
    }

    public Long getBookId() {
        return bookId;
    }

    public void setBookId(Long bookId) {
        this.bookId = bookId;
    }

    public String getBookName() {
        return bookName;
    }

    public void setBookName(String bookName) {
        this.bookName = bookName;
    }

    public Long getCategoryId() {
        return categoryId;
    }

    public void setCategoryId(Long categoryId) {
        this.categoryId = categoryId;
    }

    public String getSubTitle() {
        return subTitle;
    }

    public void setSubTitle(String subTitle) {
        this.subTitle = subTitle;
    }

    public String getAuthor() {
        return author;
    }

    public void setAuthor(String author) {
        this.author = author;
    }

    public String getCover() {
        return cover;
    }

    public void setCover(String cover) {
        this.cover = cover;
    }

    public String getDescription() {
        return description;
    }

    public void setDescription(String description) {
        this.description = description;
    }

    public float getEvaluationScore() {
        return evaluationScore;
    }

    public void setEvaluationScore(float evaluationScore) {
        this.evaluationScore = evaluationScore;
    }

    public Integer getEvaluationQuantity() {
        return evaluationQuantity;
    }

    public void setEvaluationQuantity(Integer evaluationQuantity) {
        this.evaluationQuantity = evaluationQuantity;
    }
}

@TableName("book")对照表名
@TableId(type = IdType.AUTO)
@TableField("bookId")如果数据库属性名不一致，可以调整

---

2.BookDao

public interface BookDao extends BaseMapper<Book>{

}

---

3.BookService

public interface BookService {
    /**
     * @param categoryId 分类
     * @param order      排序
     * @param page       页码
     * @param rows       页显示行数
     * @return
     */
    public IPage<Book> pageing(Long categoryId, String order, Integer page, Integer rows);

}

BookServiceImpl

@Service
public class BookServiceImpl implements BookService {

    @Autowired
    private BookDao bookDao;

    @Override
    public IPage<Book> pageing(Long categoryId, String order, Integer page, Integer rows) {
        Page<Book> p = new Page<>(page, rows);
        QueryWrapper<Book> queryWrapper = new QueryWrapper<>();
        //类别已选，可以加入sql中
        if (categoryId != null && categoryId != -1) {
            queryWrapper.eq("categoryId", categoryId);
        }
        if (order != null) {
            if("quantity".equals(order)){
                queryWrapper.orderByDesc("evaluationQuantity");
            }else if("score".equals(order)){
                queryWrapper.orderByDesc("evaluationScore");
            }
        }
        IPage<Book> bookPage = bookDao.selectPage(p, queryWrapper);
        return bookPage;
    }


}

---

4.BookServiceTest

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations = {"classpath:applicationContext.xml"})
public class BookServiceTest {

    @Autowired
    private BookService bookService;

    @Test
    public void pageing() {
        IPage<Book> bookIPage = bookService.pageing(1,2);
        List<Book> bookList = bookIPage.getRecords();
        for (Book book:bookList
             ) {
            System.out.println(book);
        }
        System.out.println(bookIPage.getPages());
        System.out.println(bookIPage.getTotal());
        System.out.println(bookIPage.getCurrent());
        System.out.println(bookIPage.getSize());
    }
}

写完service ，立马建立test测试是否能取到数据

分别是总页数，总记录数，当前页，页显示行数