用javabean写一个查询系统

最新推荐文章于 2023-02-25 19:44:55 发布

Steven郭郭

最新推荐文章于 2023-02-25 19:44:55 发布

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分类专栏： JavaBean

本文链接：https://blog.youkuaiyun.com/gh769883346/article/details/50207427

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mvc模式java类

数据库链接类

package com.csmy.db;

import java.sql.*;

public class Dao {
	static {
		try {
			Class.forName("com.mysql.jdbc.Driver");
		} catch (ClassNotFoundException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}

	public static Connection getconn() throws SQLException {
		Connection conn = null;
		conn = DriverManager
				.getConnection(
						"jdbc:mysql://127.0.0.1:3306/test?useUnicode=true&characterEncoding=UTF-8",
						"root", "root");
		return conn;
	}

	public static void closeconn(Connection conn) throws SQLException {
		if (conn != null && !conn.isClosed()) {
			conn.close();
		}
	}

}

连接类方法

package com.csmy.db;

import java.sql.*;

import com.csmy.bean.Student;
public class GetDao {
	public Student getStudent(String sno)throws SQLException {
		Connection conn = null;
		ResultSet rs=null;
		Student st=null;
		conn = Dao.getconn();
		if (conn != null) {
			String sql = "select *from students where sno=?";
			PreparedStatement ps = conn.prepareStatement(sql);
			ps.setString(1, sno);
			rs=ps.executeQuery();
			if(rs.next()){
				st=new Student();
				st.setSno(sno);
				st.setSname(rs.getString("sname"));
				st.setSsex(rs.getString("ssex"));
				st.setSage(rs.getInt("sage"));
			}
			Dao.closeconn(conn);
		}
		return st;
	}
}

数据封装

package com.csmy.bean;

public class Student {
	private String sno;
	private String sname;
	private String ssex;
	private int sage;

	public String getSno() {
		return sno;
	}

	public void setSno(String sno) {
		this.sno = sno;
	}


	public String getSname() {
		return sname;
	}

	public void setSname(String sname) {
		this.sname = sname;
	}


	public String getSsex() {
		return ssex;
	}

	public void setSsex(String ssex) {
		this.ssex = ssex;
	}


	public int getSage() {
		return sage;
	}

	public void setSage(int sage) {
		this.sage = sage;
	}

}

servlet方法

package com.csmy.servlet;

import java.io.IOException;
import java.sql.SQLException;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.csmy.bean.Student;
import com.csmy.db.GetDao;

@SuppressWarnings("serial")
public class QueryStudent extends HttpServlet {
	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		String sno = request.getParameter("sno");
		if (sno == null) {

		} else {
			GetDao dao = new GetDao();
			Student st;
			try {
				st = dao.getStudent(sno);
				if (st != null) {
					request.setAttribute("st", st);
					request.getRequestDispatcher("QueryResult.jsp").forward(
							request, response);
				} else {
					request.getRequestDispatcher("QueryStudent.jsp").forward(
							request, response);
				}
			} catch (SQLException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}
	}

	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		doGet(request, response);
	}

}

jsp页面

<%@ page language="java" import="com.csmy.bean.Student" pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <base href="<%=basePath%>">
    
    <title>学生信息查询结果</title>
    
	<meta http-equiv="pragma" content="no-cache">
	<meta http-equiv="cache-control" content="no-cache">
	<meta http-equiv="expires" content="0">    
	<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
	<meta http-equiv="description" content="This is my page">
  </head>
   <jsp:useBean id="st" type="com.csmy.bean.Student" scope="request"/>
  <body>
  查询结果：<p>
  学号：<jsp:getProperty property="sno" name="st"/>
  姓名：<jsp:getProperty property="sname" name="st"/>
  性别：<jsp:getProperty property="ssex" name="st"/>
  年龄：<jsp:getProperty property="sage" name="st"/>
  </body>
</html>

页面二

<%@ page language="java" import="java.util.*" pageEncoding="Utf-8"%>
<%
	String path = request.getContextPath();
	String basePath = request.getScheme() + "://"
			+ request.getServerName() + ":" + request.getServerPort()
			+ path + "/";
%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base href="<%=basePath%>">

<title>学生信息查询</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
</head>

<body>
	<center>
		<form action="QueryStudent" method="post">
			请输入学号： <input type="text" name="sno">
			<p>
				<input type="submit" value="查询"> <input type="reset"
					value="取消">
		</form>
	</center>
</body>
</html>