使用模糊查询和分页查询_模糊查询分页

https://blog.csdn.net/weixin_40699504/article/details/107552749
模糊分页查询

1.具体的Bean类型
一个pageinfo类型，来存储页相关的数据结构。

package com.whut.bean;
 
import java.util.List;
 
public class PageInfo<T> {
    private List<T> list;
    private int size;
    private int totalPage;
    private int totalCount;
    private int currentPage;
 
    public List<T> getList() {
        return list;
    }
 
    public void setList(List<T> list) {
        this.list = list;
    }
 
    public int getSize() {
        return size;
    }
 
    public void setSize(int size) {
        this.size = size;
    }
 
    public int getTotalPage() {
        return totalPage;
    }
 
    public void setTotalPage(int totalPage) {
        this.totalPage = totalPage;
    }
 
    public int getTotalCount() {
        return totalCount;
    }
 
    public void setTotalCount(int totalCount) {
        this.totalCount = totalCount;
    }
 
    public int getCurrentPage() {
        return currentPage;
    }
 
    public void setCurrentPage(int currentPage) {
        this.currentPage = currentPage;
    }
 
    @Override
    public String toString() {
        return "PageInfo{" +
                "list=" + list +
                ", size=" + size +
                ", totalPage=" + totalPage +
                ", totalCount=" + totalCount +
                ", currentPage=" + currentPage +
                '}';
    }
}

2.Controller类中增加一个findAll方法

@RequestMapping("/findAll.do")
    public ModelAndView findAll(@RequestParam(defaultValue = "1")int currentPage, String username, @RequestParam(defaultValue = "0")int type, HttpSession session){
        if(type==1){
            session.setAttribute("searchName",username);
        }else{
            username=(String)session.getAttribute("searchName");
        }
        PageInfo<User> pageInfo=userService.findAll(currentPage,username);
        ModelAndView mv=new ModelAndView();
        mv.addObject("pageInfo",pageInfo);
        mv.setViewName("user-list");
        return mv;
     }

3. 编写相应的sql语句到mapper类中

2.在userDao中改变findAll接口，添加一个start参数，表明模糊查询到的数据在数据库中的起始位置;并添加一个getTotalCount的接口。并在UserMapper.xml文件中改变相应的数据库查询语句,和添加相应的查询语句

<mapper namespace="com.huxiaoheng.dao.UserDao" >
 
    <select id="findAll" resultType="User">
        select * from user
        <if test="username!=null and username!=''">
            where username like concat("%",#{username},"%")
        </if>
        limit #{start},5
    </select>
    
    <select id="getTotalCount" resultType="int">
        select count(*) from user
        <if test="username!=null and username!=''">
            where username like concat("%",#{username},"%")
        </if>
    </select>
</mapper>

3.2

2.在userDao中改变findAll接口，添加一个start参数，表明模糊查询到的数据在数据库中的起始位置;并添加一个getTotalCount的接口。并在UserMapper.xml文件中改变相应的数据库查询语句,和添加相应的查询语句

4.在UserService中改变查询接口

5.在UserServiceImpl中改变接口实现方法，使其由原先的数据列表展示变为分页展示，规定每页展示五行数据

6.改变UserController中的findAll方法

4.具体的逻辑写到service层中

@Override
    public PageInfo<User> findAll(int currentPage, String username) {
        PageInfo<User> pageInfo=new PageInfo<>();
        pageInfo.setSize(5);
        //tc为查询数据的总行数
        int tc=userDao.getTotalCount(username);
        pageInfo.setTotalCount(tc);
        //tp为总页数
        int tp=(int)Math.ceil(tc/5.0);
        pageInfo.setTotalPage(tp);
        if(currentPage<1){
            pageInfo.setCurrentPage(1);
        }else if(currentPage>tp){
            pageInfo.setCurrentPage(tp);
        }else {
            pageInfo.setCurrentPage(currentPage);
        }
        int start=(pageInfo.getCurrentPage()-1)*5;
        List<User> userList=userDao.findAll(start,username);
        pageInfo.setList(userList);
        return pageInfo;
}