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用javabean写一个查询系统

2015-12-07 16:33 393 查看

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>

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