Java | 多条件模糊查询 jsp+servlet实现

根据多个条件进行模糊查询
思路：判断前端传来的数据，判断那些条件是填写的，最后在Dao层判断进行sql语句拼接

效果

具体代码实现

前端

<div style="float: right"><h3 align="center" class="form-inline">当前用户：${user}欢迎你!</h3></div>
<div align="center" style="float: left">
    <form class="form-inline" action="bookListByType" method="post">
        <div class="form-group">
            <label>图书分类</label>
            <select name="book_type" class="form-control">
                <option selected>请选择</option>
                <option>小说</option>
                <option>文学</option>
                <option>传记</option>
                <option>艺术</option>
                <option>少人</option>
                <option>经济</option>
                <option>管理</option>
                <option>科技</option>
            </select>
        </div>
        <div class="form-group">
            <label for="exampleInputEmail2">图书名称</label>
            <input type="text" class="form-control" id="exampleInputEmail2" placeholder="请输入图书名称" name="book_name">
        </div>
        <div class="form-group">
            <label>是否借阅</label>
            <select name="is_borrow" class="form-control">
                <option selected>请选择</option>
                <option>已借</option>
                <option>未借</option>
            </select>
        </div>
        <input type="submit" class="btn btn-default" value="点击查询"/>
    </form>
</div>
<table class="table table-hover">
    <tr align="center">
        <td>ID</td>
        <td>图书编号</td>
        <td>图书名称</td>
        <td>图书类型</td>
        <td>图书作者</td>
        <td>出版社</td>
        <td>出版日期</td>
        <td>是否借阅</td>
        <td>创建人</td>
        <td>创建日期</td>
        <td>最新更新时间</td>
        <td>借阅用户ID</td>
        <td colspan="2">操作</td>
    </tr>
    <c:forEach var="item" items="${bookInfos}">
        <tr align="center">
            <td>${item.book_id}</td>
            <td>${item.book_code}</td>
            <td>${item.book_name}</td>
            <td><c:choose>
                <c:when test="${item.book_type==1}">小说</c:when>
                <c:when test="${item.book_type==2}">文学</c:when>
                <c:when test="${item.book_type==3}">传记</c:when>
                <c:when test="${item.book_type==5}">艺术</c:when>
                <c:when test="${item.book_type==6}">少儿</c:when>
                <c:when test="${item.book_type==7}">经济</c:when>
                <c:when test="${item.book_type==8}">管理</c:when>
                <c:when test="${item.book_type==8}">科技</c:when>
            </c:choose>
            </td>
            <td>${item.book_author}</td>
            <td>${item.publish_press}</td>
            <td>${item.publish_date}</td>
            <td>
                <c:choose>
                    <c:when test="${item.is_borrow==1}">已借</c:when>
                    <c:when test="${item.is_borrow==0}">未借</c:when>
                </c:choose>
            </td>
            <td>${item.createdBy}</td>
            <td>${item.creation_time}</td>
            <td>${item.last_updatetime}</td>
            <td>${item.user_id}</td>
            <td><a href="${pageContext.request.contextPath}/bookInfoListById?id=${item.book_id}">修改</a></td>
            <td><a href="${pageContext.request.contextPath}/deleteBookInfoById?id=${item.book_id}">删除</a></td>
        </tr>
    </c:forEach>
</table>

servlet

package com.library.servlet;

import com.library.pojo.BookInfo;
import com.library.service.BookInfoService;
import com.library.service.impl.BookInfoServiceImpl;

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 java.io.IOException;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

@WebServlet("/bookListByType")
public class BookListByType extends HttpServlet {
    BookInfoService bookInfoService = new BookInfoServiceImpl();

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        this.doPost(req, resp);
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        req.setCharacterEncoding("utf-8");
        resp.setContentType("utf-8");
        String book_name = "未选择";
        Map<String, Integer> map = new HashMap<>();
        map.put("请选择", 0);
        map.put("小说", 1);
        map.put("文学", 2);
        map.put("传记", 3);
        map.put("艺术", 4);
        map.put("少儿", 5);
        map.put("经济", 6);
        map.put("管理", 7);
        map.put("科技", 8);
        int book_type = map.get(req.getParameter("book_type"));
        String s1 = req.getParameter("book_name");
        if (!"".equals(s1)) {
            book_name = req.getParameter("book_name").trim();
        }
        Map<String, Integer> map1 = new HashMap<>();
        map1.put("请选择", -1);
        map1.put("已借", 1);
        map1.put("未借", 0);
        int is_borrow = map1.get(req.getParameter("is_borrow"));
        List<BookInfo> bookInfos = bookInfoService.BookListByType(book_type, book_name, is_borrow);
        req.setAttribute("bookInfos", bookInfos);
        req.getRequestDispatcher("bookinfolist.jsp").forward(req, resp);
    }
}

工具类Util

package com.library.util;

import com.alibaba.druid.pool.DruidDataSourceFactory;

import javax.sql.DataSource;
import java.lang.reflect.Field;
import java.sql.*;
import java.util.ArrayList;
import java.util.List;
import java.util.Properties;

public class Utils {
    private static DataSource dataSource;

    // 初始化配置
    static {
        try {
            Properties properties = new Properties();
            properties.load(Utils.class.getClassLoader().getResourceAsStream("druid.properties"));
            dataSource = DruidDataSourceFactory.createDataSource(properties);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    // 获取连接
    public static Connection getConnection() throws SQLException {
        return dataSource.getConnection();
    }

    // 释放资源
    public static void close(ResultSet resultSet, Statement statement, Connection connection) {
        if (resultSet != null) {
            try {
                resultSet.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        if (statement != null) {
            try {
                statement.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        if (connection != null) {
            try {
                connection.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }

    // 通用查询参数用Object数组存储
    public static <T> List<T> executeQuery(String sql, Object[] params, Class<T> clazz) {
        List<T> list = new ArrayList<>();
        ResultSet resultSet = null;
        PreparedStatement preparedStatement = null;
        Connection connection = null;
        try {
            connection = getConnection();
            preparedStatement = connection.prepareStatement(sql);
            if (params != null) {
                for (int i = 0; i < params.length; i++) {
                    preparedStatement.setObject(i + 1, params[i]);
                }
            }
            resultSet = preparedStatement.executeQuery();
            while (resultSet.next()) {
                T t = clazz.newInstance();
                Field[] declaredFields = clazz.getDeclaredFields();
                for (int i = 0; i < declaredFields.length; i++) {
                    declaredFields[i].setAccessible(true);
                    declaredFields[i].set(t, resultSet.getObject(declaredFields[i].getName()));
                }
                list.add(t);
            }
        } catch (SQLException | InstantiationException | IllegalAccessException e) {
            e.printStackTrace();
        } finally {
            close(resultSet, preparedStatement, connection);
        }
        return list;
    }

    // 通用查询参数用ArrayList集合存储
    public static <T> List<T> executeListQuery(String sql, ArrayList params, Class<T> clazz) {
        List<T> list = new ArrayList<>();
        ResultSet resultSet = null;
        PreparedStatement preparedStatement = null;
        Connection connection = null;
        try {
            connection = getConnection();
            preparedStatement = connection.prepareStatement(sql);
            if (!params.isEmpty()) {
                for (int i = 0; i < params.size(); i++) {
                    preparedStatement.setObject(i + 1, params.get(i));
                }
            }
            resultSet = preparedStatement.executeQuery();
            while (resultSet.next()) {
                T t = clazz.newInstance();
                Field[] declaredFields = clazz.getDeclaredFields();
                for (int i = 0; i < declaredFields.length; i++) {
                    declaredFields[i].setAccessible(true);
                    declaredFields[i].set(t, resultSet.getObject(declaredFields[i].getName()));
                }
                list.add(t);
            }
        } catch (SQLException | InstantiationException | IllegalAccessException e) {
            e.printStackTrace();
        } finally {
            close(resultSet, preparedStatement, connection);
        }
        return list;
    }

    // 通用增删改
    public static int executeUpdate(String sql, Object[] params) {
        PreparedStatement preparedStatement = null;
        Connection connection = null;
        int num = -1;
        try {
            connection = getConnection();
            preparedStatement = connection.prepareStatement(sql);
            if (params != null) {
                for (int i = 0; i < params.length; i++) {
                    preparedStatement.setObject(i + 1, params[i]);
                }
            }
            num = preparedStatement.executeUpdate();
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            close(null, preparedStatement, connection);
        }
        return num;
    }

    // 获取数据资源
    public static DataSource getDataSource() {
        return dataSource;
    }
}

service

public List<BookInfo> BookListByType(int book_type, String book_name, int is_borrow) {
        return bookInfoDao.BookListByType(book_type, book_name, is_borrow);
    }

Dao

public List<BookInfo> BookListByType(int book_type, String book_name, int is_borrow) {
        String sql = "select * from book_info where 1=1";
        String ss = "%" + book_name + "%";
        String type = " and book_type = ?";
        String name = " and book_name like ?";
        String borrow = " and is_borrow = ?";
        StringBuffer stringBuffer = new StringBuffer(sql);
        ArrayList params = new ArrayList<>();
        if (book_type != 0) {
            params.add(book_type);
            stringBuffer.append(type);
        }
        if (!"未选择".equals(book_name)) {
            params.add(ss);
            stringBuffer.append(name);
        }
        if (is_borrow != -1) {
            params.add(is_borrow);
            stringBuffer.append(borrow);
        }
        return Utils.executeListQuery(stringBuffer.toString(), params, BookInfo.class);
    }

pojo

package com.library.pojo;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

@Data
@NoArgsConstructor
@AllArgsConstructor
public class BookInfo {
    private int book_id;
    private String book_code;
    private String book_name;
    private int book_type;
    private String book_author;
    private String publish_press;
    private String publish_date;
    private int is_borrow;
    private String createdBy;
    private String creation_time;
    private String last_updatetime;
    private int user_id;

    public BookInfo(String book_code, String book_name, int book_type, String book_author, String publish_press, String publish_date, int is_borrow, String createdBy, String creation_time, String last_updatetime, int user_id) {
        this.book_code = book_code;
        this.book_name = book_name;
        this.book_type = book_type;
        this.book_author = book_author;
        this.publish_press = publish_press;
        this.publish_date = publish_date;
        this.is_borrow = is_borrow;
        this.createdBy = createdBy;
        this.creation_time = creation_time;
        this.last_updatetime = last_updatetime;
        this.user_id = user_id;
    }
}