小编典典

传递Date参数以创建日期范围查询

jsp

使用以下代码,我想问一下如何传递来自文本字段的“日期”参数。我打算使用DAO和servlet创建一个简单的日期范围查询。我可以使用此代码显示所有列,但是我想使用日期进行过滤…

这是我的代码:

My Servlet




package source;

import java.io.*;
import java.sql.SQLException;
import java.util.*;
import javax.servlet.ServletException;
import javax.servlet.http.*;

/**
 *
 * @author jaypee.martinez
 */
public class parseServlet extends HttpServlet {

    private parseDAO parseDAO;


    @Override
    public void init() throws ServletException {
        String driver = "org.postgresql.Driver";
        String url = "jdbc:postgresql://localhost5432/mydb";
        String username = "postgres";
        String password = "secret";


        Database database = new Database(driver, url, username, password);
        this.parseDAO = new parseDAO(database);
    }


    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {


            try {

            List<parseBean> parse_array = parseDAO.results();

            request.setAttribute("parse_array", parse_array);
            request.getRequestDispatcher("results.jsp").forward(request, response);
        }
            catch (SQLException e) {
            throw new ServletException("Cannot retrieve areas", e);
        }
    }

}

和我的DAO

/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */

package source;

import java.sql.*;
import java.sql.SQLException;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.*;

public class parseDAO {

    private Database database;

    public parseDAO(Database database) {
        this.database = database;
    }

    public List<parseBean> results() throws SQLException {
        Connection connection = null;
        PreparedStatement statement = null;
        ResultSet resultSet = null;
        List<parseBean> parse_array = new ArrayList<parseBean>();
        SimpleDateFormat df=new SimpleDateFormat("yyyy-MM-dd");

        try {
            connection = database.getConnection();
            statement = connection.prepareStatement("select * from dateparse");


            resultSet = statement.executeQuery();


            while (resultSet.next()) {
                parseBean parsearray = new parseBean();
                parsearray.setDate(resultSet.getDate("date"));
                parsearray.setName(resultSet.getString("name"));
                parsearray.setAddress(resultSet.getString("address"));
                parse_array.add(parsearray);
            }
        } finally {
            if (resultSet != null) try { resultSet.close(); } catch (SQLException logOrIgnore) {}
            if (statement != null) try { statement.close(); } catch (SQLException logOrIgnore) {}
            if (connection != null) try { connection.close(); } catch (SQLException logOrIgnore) {}
        }

        return parse_array;
    }
}

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2020-06-10

共1个答案

小编典典

使用HttpServletRequest#getParameter()收集请求参数。假设输入字段具有名称date

String dateString = request.getParameter("date");

使用SimpleDateFormat#parse()将其转换为java.util.Date使用特定的模式,根据不同的终端用户是如何要求输入的日期。

Date date = null;

try {
    date = new SimpleDateFormat("yyyy-MM-dd").parse(dateString);
}
catch (ParseException e) {
    // Show error message to enduser about the wrong format and forward back to the JSP with the form.
    request.setAttribute("error", "Invalid format, please enter yyyy-MM-dd");
    request.getRequestDispatcher("search.jsp").forward(request, response);
    return;
}

将此作为方法参数传递给您的DAO方法:

List<ParseBean> results = parseDAO.search(date);

您需要将其转换为java.sql.Date,以便可以PreparedStatement#setDate()在SQL查询中进行设置:

String query = "SELECT * FROM dateparse WHERE date = ?";
// ...
statement.setDate(1, new java.sql.Date(date.getTime()));

您可以WHERE date > ?用来搜索WHERE date < ?早于给定日期的记录,或者搜索早于给定日期WHERE date BETWEEN ? and ?的记录,或者搜索指定日期之间的记录。

2020-06-10