传递Date参数以创建日期范围查询

使用下面的代码，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Date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 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 results() throws SQLException { Connection connection = null; PreparedStatement statement = null; ResultSet resultSet = null; List parse_array = new ArrayList(); 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; } } 

Answer 1

使用HttpServletRequest#getParameter()来收集请求参数。 假设输入字段的名称为date 。

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

使用SimpleDateFormat#parse()将其转换为java.util.Date使用特定模式，具体取决于要求最终用户输入日期的方式。

 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DAO方法：

 List results = parseDAO.search(date); 

您需要将其转换为java.sql.Date ，以便您可以使用PreparedStatement#setDate()在SQL查询上设置它：

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

你可以使用WHERE date > ? 搜索比给定日期更新的记录，或者WHERE date < ? 搜索超过给定日期的记录，或者WHERE date BETWEEN ? and ? WHERE date BETWEEN ? and ? 搜索指定日期之间的记录。

Answer 2

在您的doGet您将从请求中获得价值

 String dateFromTxt = request.getParameter("DateFromTxtField"); 

将此传递给您的dao的results方法

那么你的results方法可能如下所示：

 public List results(String filterDate) throws SQLException { String query = "select * from dateparse where date = ? "; // get connection and prepare statement, also format the incoming date as per your database requirement then say you store this in variable myFormattedDate statement.setDate(1, myFormattedDate); // Execute query and fetch result. }