JavaWeb学习-关键字查询

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1. index.html

<div>
    <form th:action="@{/index}" method="post">
        <input type="hidden" name="oper" value="search" />
        请输入查询关键字：<input type="text" name="keyword" th:value="${session.keyword}"/>
        <input type="submit" value="查询"/>
    </form>
    <a th:href="@{/add.html}">添加信息</a>
</div>

2. IndexServlet

package com.fruits.servelet;

import com.fruits.dao.FruitDAO;
import com.fruits.dao.Impl.FruitDAOImpl;
import com.fruits.pojo.Fruit;
import com.fruits.util.StringUtil;
import com.myssm.myspringmvc.ViewBaseServlet;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.io.IOException;
import java.util.List;

@WebServlet("/index")
public class IndexServlet  extends ViewBaseServlet {
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doGet(req,resp);
    }

    @Override
    public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        request.setCharacterEncoding("utf-8");
        HttpSession session=request.getSession();
        int pageNo = 1;
        String oper = request.getParameter("oper");
        //如果oper不是空的，则是通过表单的查询按钮点击过来的，
        //如果oper是空的，说明不是通过表单的查询按钮点击过来的，
        // 因为index文件可以通过点击分页按钮进入，增删改后也可以进入。
        String keyword = null;
        if(StringUtil.isNotEmpty(oper)&&"search".equals(oper)){
            //是通过表单的查询按钮点击过来的，
            //此时，pageNo应该还原为 1 ， keyword应该从请求参数中获取
            pageNo=1;
            keyword = request.getParameter("keyword");
            if(StringUtil.isEmpty(keyword)){
                keyword = "";
            }
            session.setAttribute("keyword",keyword);
        }else{
            //说明不是通过表单的查询按钮点击过来的，（比如点击上一页下一页或者直接在地址栏中输入网址 ）
            //此时keyword应该从session作用域中获取
            String pageNoStr = request.getParameter("pageNo");
            if(StringUtil.isNotEmpty(pageNoStr)){
                pageNo = Integer.parseInt(pageNoStr);
            }
            Object keywordobj = session.getAttribute("keyword");
            if(keywordobj!=null){
                keyword = (String)keywordobj;
            }else{
                keyword="";
            }
        }

        session.setAttribute("pageNo",pageNo);

        FruitDAO fruitDAO=new FruitDAOImpl();
        //List<Fruit> fruitList = fruitDAO.getFruitList();
         //List<Fruit> fruitList = fruitDAO.getFruitListbypageNo(pageNo);
        List<Fruit> fruitList = fruitDAO.getListbypageNo(keyword, pageNo);
        session.setAttribute("fruitList", fruitList);

        //总记录条数
       // int count = fruitDAO.getFruitCount();
        int count = fruitDAO.getCount(keyword);
        //总页数
        int pageCount = count/5+1;
        session.setAttribute("pageCount", pageCount);


        //此处的视图名称是index，
        //那么thymeleaf会将这个 逻辑视图名称 对应到 物理视图 名称上去
        //逻辑视图名称：index
        //物理视图名称： view-prefix+逻辑视图名称+view-suffix
        //所以真是的视图名称为   /   index.    html
        super.processTemplate("index",request,response);
    }

3.FruitDAO和FruitDAOImpl

//关键字查询且分页
List<Fruit> getListbypageNo(String keyword,int pageNo);
//获取库存总页数+关键字查询
int getCount(String keyword);

 public List<Fruit> getListbypageNo(String keyword, int pageNo) {
        List<Fruit> list = new ArrayList<>();
        getConn();

        String sql = "select * from fruit where fname like ? or remark like ? LIMIT ?,5";
        try {
            ps = conn.prepareStatement(sql);
            ps.setString(1,"%"+keyword+"%");
            ps.setString(2,"%"+keyword+"%");
            ps.setInt(3,(pageNo-1)*5);
            rs = ps.executeQuery();
            while (rs.next()){
                Fruit fruit = new Fruit();
                fruit.setFid(rs.getInt(1));
                fruit.setFname(rs.getString(2));
                fruit.setPrice(rs.getInt(3));
                fruit.setFcount(rs.getInt(4));
                fruit.setRemark(rs.getString(5));
                list.add(fruit);
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return list;
    }


    @Override
    public int getCount(String keyword) {
        int count = 0;
        String sql = "select * from fruit where fname like ? or remark like ?";
        getConn();
        try {
            ps = conn.prepareStatement(sql);
            ps.setString(1,"%"+keyword+"%");
            ps.setString(2,"%"+keyword+"%");
            rs = ps.executeQuery();
            while (rs.next()){
                count++;
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return count;
    }

 

文章来源:https://www.cnblogs.com/Joyce-mi7/p/16494487.html
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